D4.7 – Basic global prediction tool and user manual
Contents
1. Track Decay Rates ROUGHNESS Select Option Unit roughness 16 5 m Load from file Standard TSI Without Q9 Load one file roughness s Load two files roughness p prm Remove aco power Plot aco power Attach acoustic power Figure 7 Defining a rolling noise input for a specific wheelset type There are two different ways to load sound power into the software in both the cases the sound powers are meant to be calculated with a unit 1 m roughness input e Loading single power files Wheel power rail power and sleeper power txt files can be selected after clicking the button Load text files The file format is similar to that used for the point sources with the peculiarity that the first string in the file must be wheel rail or sleep according to the power component the file refers to ACT WP4 D ISV 022 02 Page 12 of 43 30 06 2014 addiTRAIN EC Contract No FP7 284877 dL e Selecting a TWINS folder If the outputs of the software TWINS are available then the Select TWINS dir button allows the user to browse in order to select a TWINS model folder outputs from TWINS 2 4 have been tested so far Sound powers will be detected inside the folder and loaded along with the Track Decay Rates The contact filter is always accounted for allowing for the train speed set in the Operating Conditions window see S2. 1 Z Fh phiim repmat phiim 1 1 1 Nf ths r thim epmat ths 1 1 1 Nf repmat thim 1 1 1 Nf ACT WP4 D ISV 022 02 Page 39 of 43 30 06 2014 EC Contract No FP7 284877 wcbbTRAIN modified frequency k0 2 pi f0 c0 fs 1 1 M cos Betas 0 fim 1 1 M cos Betaim 0 SGround model Switch ground model case off Ref1 20 case Rigid Refl 1 case DelBaz Refl DelBazGround phig Rim fim prop case Miki Refl MikiGround phig Rim fim prop case HamBer Refl HamBerGround phig Rim fim prop end tmp al1S DipAx pi 180 dipaxl tmp 1 2 end dipax2 tmp 2 2 end Gs Ds exp li k0 Rs Gims Dim Refl exp li k0 Rim Gtot Gs Gims TA Lpnar Lwnar 10 10g10 rho0 c0 Wref pref 2 abs Gtot 2 4 pi REPLICATE ROLLING NOISE PER WLSTS if isequal allS isTWINS zeros size allS isTWINS uu 0 wlstset allx0 2 end wlstset allx0 1 uu uu v ind zeros size uu LpnarRep sRep for ix0 1 length wlstset allx0 ind ixO find time uu ix0 1 last M 2007 2013 4 pi Rs 1 M cos Betas 2 4 pi Rim 1 M cos Betaim 2 LpnarRep LpnarRep Lpnar ind ix0 ind ix0O OC T prop Dt fsRep fsRep fs ind ix0 ind ix0 OC T prop Dt end Nt OC T prop Dt 1 Ns Ns length wlstset allx0 Lpnar LpnarRep fs fsRep
3. 7 OPERATING CONDITIONS To define the operating conditions of the train the type of the test has to be defined Operating conditions in Create menu Passby at a constant speed or stand still mode are allowed When considering the passby mode the test duration can be modified here The test duration will also define the relative position between the train and the x coordinates of the receivers The receivers are set to be in front of the middle of the train at half of the test duration time This parameter is displayed in the software windows but it cannot be modified 8 RECEIVERS Receivers can be added and edited through the Define receivers function see Figure 9 inside the Create menu Default TSI positioning is available but further single receivers can be input one by one or loaded from a text file see Section 11 Right click on the receivers shown in the figure for editing and deleting In addition in case of standstill condition the number of receiver related to each car can be modified by the context menu available by right clicking on the car bogy FE F E Receivers Hide show text Export image y m xz xz T Testtype os Pan zoom roa 30 Passby Standstill L Default TSI Add receiver Load from fie Clear all Figure 9 Example of receiver positions for stand still calculation ACT WP4 D ISV 022
4. s Time s Update V A weigth Export as text Export figure Exit Figure 10 Results view the example shown is for two dipole sources 20 m a part and at 4 m above the ground moving at 80 km h above an absorptive ground Their acoustic power is defined as a flat spectrum of 120 dB re 10 W 10 FILE MANAGEMENT When the software saves the model File Save Save as both the geometrical physical and numerical results are stored in the indicated folder When the model is loaded File gt Load file no check is made whether the file contains or not results present the results will be modified after the RUN button is pressed inside the Calculate GUI 11 FILE FORMAT FOR UPLOADING DATA 11 1 SOUND POWERS The sound powers directivity information and roughness level to be loaded in the software are prepared by the user in text files Apart from the roughness level the format of the file is common for all the type of source ACT WP4 D ISV 022 02 Page 16 of 43 30 06 2014 Nel EC Contract No FP7 284877 d This is a txt containing a matrix of strings and numbers The elements of the matrix should be separated by the character Tab The first element of the matrix is an alphanumeric string that identifies the type of data included in the file In the current version of the software the first column from the second element onwards is not used In a future version of the software this will indicate the running
5. 30e5 SFlow resistivity ACT WP4 D ISV 022 02 Page 41 of 43 30 06 2014 wcbirr ain EC Contract No FP7 284877 M l Sthickness Sh Stortuosity s Sporosity function Refl DelBazGround phig Rim f prop Delany Bazley model for ground impedance with in finite Sthickness kim 2 pi f prop c0 zng 1 9 08 1000 f sigmae 0 75 11 9 1i 1000 f sigmae 0 73 ground thickness if isempty 1 km 2 pi f prop cO 14 10 8 1000 f sigmae 0 7 1j 10 3 1000 f sigmae 59 km wavenumber in material zng 1j zng cot km 1 end Refl ReflCoeff zng phig kim Rim end function Refl MikiGround phig Rim f prop Miki model for ground impedance with in finite thickness kim 2 pi f prop c0 zng 1 5 50 1000 f sigmae 0 632 8 43 1i 1000 f sigmae 0 632 9 5 ground thickness if isempty 1 km 2 pi f prop cO 147 81 1000 f sigmae 0 618 1j 11 41 1000 f sigmae 618 km wavenumber in material zng 1j zng cot km 1 end Refl ReflCoeff zng phig kim Rim end function Refl HamBerGround phig Rim f prop Hamet amp Berang model for ground impedance with in finite Sthickness ACT WP4 D ISV 022 02 Page 42 of 43 30 06 2014 Nera EC Contract No FP7 284877 M Npr 0 7 gamma 1 4 kim 2 pi f prop c0 zng h s 1 sigmae s li prop rho0 h 2 2 pi f 1 2 1 sigmae li
6. 32 bit runtime compiler launch the executable file to run the software 2 OVERVIEW The software works by defining noise sources which are each associated with a vehicle Several vehicles are assembled to make a train Noise sources may be associated with rolling noise or other types of noise source They are defined in terms of their sound power in one third octave bands and a directivity The receiver locations are defined as well as the ground properties Then sound pressure can be calculated either at stand still or during a train passby Note that the geometry of the vehicle displayed in the figures is for visualisation purposes only and the train body does not modify the acoustic propagation in any way In other words there are no shielding or diffraction effects directly considered in the software 2 1 FRAME OF REFERENCE The main Cartesian frame of reference is defined as follows see Figure 1 e xaxis gt positive direction as the positive train velocity e zaxis gt vertical direction positive upwards e yaxis gt defined according to right handed orientation The origin of the x axis is set at the end of the last vehicle of a train y origin is at the middle of the train and the vertical origin is at the top of the rail Spherical coordinates are also used To describe the position of a point in space according to a spherical coordinate system the convention of Figure 1 dashed lines is adopted where 8 is the polar angle e
7. Add pantograph 0 Wheelsets per vehicle 2 SST at AEN pantograph s Add wheelset Remove last one Bogie centre distance m 18 Bogie wheelbase m ox Add sources Sawe vehicle Cancel Ok Figure 3 Describing new vehicle parameters Here it can be decided whether to create a new vehicle or load an existing one In order to create a new one the main parameters have to be inserted in the Define vehicle geometry panel Once the parameters have been inserted press the ok button located inside this panel The axes on the right are then updated and other panels are activated Within ACOUTRAIN rolling noise is associated with wheelsets The wheelsets are characterized by their position on the vehicle x coordinates of the wheelsets relative to the first end of the vehicle and by their type or the set they belong to Before adding a wheelset it is therefore necessary to create a wheelset type When starting a new model no types are available They can be created through the functionalities given in the wheelsets type panel The wheelset type contains the information about the wheel radius and about the results coming from TWINS calculation these will be loaded later on see Section 5 To create a new type enter the wheel radius associated with it and the name of the set then press the button Create new The list of available sets will be updated The existing sets can be then edited or deleted as require
8. Alternatively the sound pressure level related to a selected time step can also be shown The results shown in the main axes can be exported in a text file Export as text or in a Matlab figure Export figure As an additional aid to the user the window also shows the coordinates of the selected receiver position the overall level of the L 7 and the maximum level of the time evolution of sound pressure level This latter is denominated as L 4rmax although it does not always correspond to the quantity defined in acoustic standards 4 as the time step of the software can be modified by the user In case of standstill condition one more item is added to the list of receivers If selected the spectrum and overall level plotted in the frequency domain mode refer to a combination of all microphones as TT da ios X A otre E i tot where L is the sound pressure level measured at position i n is the number of microphones is the length associated with the microphone and finally y A complete more description is reported in 3 ACT WP4 D ISV 022 02 Page 15 of 43 30 06 2014 Nella EC Contract No FP7 284877 M ja a ViewRes z r Receiver position LpAeq Tp LpAFMax Receiver x m 122 6 104 9 105 5 R1 Y y m 75 z m 1 2 r Select Source Global level Vehicle Source a Y b hd Time Quantity Global value v dBA Update r Frequency Quantity Lp X Time
9. E 11 1 1990 pp 19 24 3 http apmr matelys com PropagationModels MotionlessSkeleton DelanyBazleyMikiModel html 4 M C B rengier M R Stinson G A Daigle and J F Hamet Porous road pavements Acoustical characterization and propagation effects vol 101 no 1 pp 155 162 Jan 1997 5 K Attenborough Sound proapagtion in the atmosphere In M J Crocker ed Handbook of noise and vibration control John Wiley amp sons 2007 6 Leping Feng Mats Abom Source model for cooling fans suitable for integration in the global simulation model Deliverable 3 1 for ACOUTRAIN project ACT WP4 D ISV 022 02 Page 36 of 43 30 06 2014 Nella EC Contract No FP7 284877 M APPENDIX B MAIN CALCULATION ROUTINES FROM THE SOFTWARE B 1 GEOMETRICAL DATA x0 initial x coordinate of all sources y0 initial y coordinates of all sources z0 initial z coordinates of all sources rh height of ground Sxr initial x coordinate of all receivers yr initial y coordinates of all receivers zr initial z coordinates of all receivers SDoppEff flag for Doppler effect Dt Time spacing Time test duration cO0 speed of sound v train speed if DoppEff M v c0 else M 0 end if v t 0 else t 0 Dt Time end Ns length x0 Nr length xr Nt length t x0 repmat x0 1 Nt Nr xr repmat xr Ns Nt 1 yO repmat yO 1 Nt Nr z0 repmat z0 1 Nt Nr t repmat t
10. and the ground is to be defined fet 9 atan A 14 im xy A 3 DOPPLER EFFECT According to the well known Doppler effect the perceived frequency of a moving source perceived by a standing receiver is shifted by a quantity related to the Mach number and to the angle of Figure A 4 and of Figure A 5 The frequency vector for the moving source is shifted according 1 Mo A 15 The frequency vector for the image source is in theory shifted by a different factor 1 Fin 1 M cos Z fo A 16 However for the positions of sources normally found in this application the difference between A 15 and A 16 is negligible and only A 15 is adopted to describe the frequency vector shifted according to the Doppler Effect A 4 SOUND PRESSURE CONTRIBUTION OF THE SOURCE The fundamental solution also called Green s function of the radiating source is exp ik R 4aR 1 cos Z A 17 where D represents the source directivity which depends on source and receiver positions ko oyc while the other quantities are as defined above A 5 SOUND PRESSURE CONTRIBUTION OF THE IMAGE SOURCE The fundamental solution is in this second case exp ik K 2 ji A 18 G R im efl im AAR cos B um L Along with the directivity factor Dim note the presence of the reflection coefficient R 7 The image source path is the one modified by the ground A 6 TOTAL CONTRIBU
11. configuration of the source The character 0 can be inserted 11 1 1 Single point source The identifier for this source is PointS This string has to be written in the first position of the matrix inside the file In the first row starting from the second element the one third octave centre frequency value should be reported The second row starting from the second element describes the sound power levels in one third octave bands An example is shown below PointS 2 5 3125 40 50 63 m 10000 0 50 52 60 55 55 bes 55 11 1 2 Area Source The same file format as for the single point source is adopted The loaded power is equally divided by the software into 16 sub sources As the input for this type of source is the same as the one for the point source the same identifier is also adopted PointS Whether it is an area source or a point source is a property that is assigned to the source through the graphical interface 11 1 3 Box source In case of box sources six power vectors are required one for each face The text format file is the same but in this case the second column from the second element onward reports the face number see Figure 11 to which the corresponding acoustic power is associated If one or more face is not radiating instead of face number the number 0 has to be written yet in the corresponding row of acoustic power values have to be written They will be used only in case the face is act
12. ebl rnaN EC Contract No FP7 284877 d Virtual certification of acoustic performance for freight and passenger trains D 4 7 Basic global prediction tool and user manual final update of D4 2 Due date of deliverable 31 05 2014 Actual submission date 30 06 2014 Leader of this Deliverable David Thompson Giacomo Squicciarini ISVR Reviewed Y Document status Revision Date Description 1 06 06 2014 First issue 2 30 06 2014 Final version after TMT approval Project co funded by the European Commission within the Seven Framework Programme 2007 2013 Dissemination Level PU Public X PP Restricted to other programme participants including the Commission Services Restricted to a group specified by the consortium including the Commission RE Services CO Confidential only for members of the consortium including the Commission Services Start date of project 01 10 2011 Duration 36 months Collaborative project Nel EC Contract No FP7 284877 M EXECUTIVE SUMMARY The present document is an update of Deliverable 4 2 It contains an updated description of the ACOUTRAIN software for pass by and standstill noise simulation developed within Task 4 2 and explains the theory implemented in the software to calculate the noise propagation of a series of moving or standstill sources above an impedance ground The objective of this task is to implement a
13. end Sthird octave band calculation if DoppEff with doppler effect Lp NaN ones Ns Nt Nr 31 LpA Lp centfreq Lp for is 1 Ns for ir 1 Nr ACT WP4 D ISV 022 02 Page 40 of 43 30 06 2014 ebl rnaN EC Contract No FP7 284877 M for it 1 Nt tmps Lpnar is it ir tmpf fs is it ir tmp3 ftmp noct tmps tmp3A Aweging ftmp tmp3 indf round 10 1ogl10 ftmp 12 p is it ir indf tmp3 pA is it ir indf tmp3A centfreq is it ir indf ftmp end end end else no need to do third octave band separately without DE tmps permute Lpnar 4 1 2 3 tmps reshape tmps Nf Ns Nt Nr tmpf squeeze fs 1 1 1 tmp3 ftmp noct_fast tmps tmpf 3 10 tmp3A Aweging ftmp tmp3 tmpf 3 10 addst round 10 10g10 ftmp 1 13 if addst lt 0 addst 0 end addend round 10 10g10 ftmp end 43 if addend 0 addend 0 end tmp3 NaN ones addst size tmp3 2 tmp3 NaN ones addend size tmp3 2 tmp3A NaN ones addst size tmp3A 2 tmp3A NaN ones addend size tmp3A 2 ftmp NaN ones addst 1 ftmp NaN ones addst 1 tmp3 reshape tmp3 size tmp3 1 Ns Nt Nr tmp3 permute tmp3 2 3 4 1 tmp3A reshape tmp3A size tmp3A 1 Ns Nt Nr tmp3A permute tmp3A 2 3 4 1 Lp tmp3 LpA tmp3A 1 1 1 ftmp centfreq repmat ff Ns Nt Nr 1 end centfreq centfreg fnar fs Lp Lp LpA LpA Lpnar Lpnar B 3 GROUND MODELS sigmae
14. prop rho0 Npr 2 pi f e 0 42 j 1 sigmae gamma li prop rhoO0 Npr 2 pi f 1 2 zng conj zng was defined with exp iwt convention ground thickness if isempty 1 km 2 pi f prop cO h 1 sigmae s li prop rho0 h 2 2 pi f 1 2 1 sigmae li prop rho0 Npr 2 pi f y 1 2 1 sigmae gamma li prop rho0 Npr 2 pi f 4 1 2 o km wavenumber in material km conj km zng 1j zng cot km 1 end Refl ReflCoeff zng phig kim Rim end function Refl ReflCoeff zng phig kim Rim Rpl zng cos phig 1 zng cos phig 1 switch to exp i w t w 0 5 1 1j sqrt kim Rim cos phig 1 conj zng F 1 1i sqrt pi w erfccomplex w switch back to exp ti w t F conj F Refl Rpl 1 Rpl F end ACT WP4 D ISV 022 02 Page 43 of 43 30 06 2014
15. rule of the nearest point always applies If the source is radiating in only half space the relative directivity values have to be set equal to 0 e tis assumed that the measurements points over the sphere are defined in such a way to divide the sphere into equal areas 5 This assumption is used in converting sound pressure levels into directivity factor e This functionality has not yet been tested with actual measurement data 11 3 FREQUENCY DEPENDENT AERODYNAMIC COEFFICIENT The aerodynamic coefficient for the speed dependent acoustic power as defined in Section A 9 can be made frequency dependent by loading a text file The file format is the same as described in Section 11 1 The file identifier is the string aercf aercf 100 125 160 200 36 10000 0 60 60 65 65 65 m 70 ACT WP4 D ISV 022 02 Page 20 of 43 30 06 2014 Nel EC Contract No FP7 284877 M 11 4 ROUGHNESS After three heading lines three numbers define the wavelength range The first number say x represents the longer wavelength the relationship between x and the longer wavelength 4 is 1 x 10 10 A Similarly the second number defines the shortest wavelength available The last number defines the wavelength step and should be always set equal to 1 indicating thus that the wavelength corresponding to a one third octave frequency resolution are adopted Afterwards the roughness levels as in defined ISOS3095 3 should be reported ACOUTRAIN rolling
16. speed and the speed of sound c in air while R is the distance between Xim YimZim and the receiver at time t An expression for R can be obtained as 2 R im0 imQ i im0 A 8 im M 1 Mx Mxing M rZo trot x 2X Ximo HX ACT WP4 D ISV 022 02 Page 28 of 43 30 06 2014 Nel EC Contract No FP7 284877 M where rimo represents the distance between the actual position of the image source at time and receiver in the vertical plane y z as Fimo Jo na z E nn A 9 In case of the image source it is useful to evaluate the position of the reflecting point x y z This can be done in two steps Firsts the position of the reflecting point related to the actual source position Xim0sYim0 Zimo is Yoo Yr Yeo Yr X oo t ee Lee x ee x Yo Yr Yo 7 Yr zs oat ch A 10 Y z h A 10 z h Zgo h from which the position x y Z can be obtained Yeo Y X E 9 X 9 cu Ys Y yg f 7 y o9 0 A11 Ze t 7 z 9 t The angle m of Figure A 5 can be evaluated as Bn acos af Tin The two angles 6 and related to the source position Xim y z are Pin atan se X 7 Xim A 12 Z Z A 12 0 atan im xy Rimxy represents the distance between the position Xim Vin Zim and the point x y Zg ACT WP4 D ISV 022 02 Page 29 of 43 30 06 2014 Nel ain EC Contract No FP7 284877 M Finally also the angle of incidence between acoustic ray
17. type 3 Edit type f L Radius m 0 Delete 10 15 20 Set name Create new Available types Edit a tA L Delete Add wheelsets Add standard bogies Pantograph Vehicle Position Add pantograph 0 CETUR pantograph s Remove last one r Add single wheelset Add wheelset Wheelsets per vehicle Bogie centre distance m Bogie wheelbase m X Add sources Save vehicle Cancel Figure 4 Right click on the wheelset to edit its properties 3 1 ADD SOURCES The software allows now some general sources to be added The add sources button opens the window shown in Figure 5 First the frequency range has to be set All the files to be loaded within this window refer to the specific source which is being defined and must match this frequency range ACT WP4 D ISV 022 02 Page 9 of 43 30 06 2014 adbbrRAIN EC Contract No FP7 284877 2007 2013 Directivity Frequency range From 13 20Hz to 43 20kHz Use standard Source type Source name noname Point source Area source Box source Standard directivity 5 Load file Frequency Hz panies a 20 Monopole Dipole Load file i25 E 31 5 5 1 Reset All 140 50 63 Dipole axis pem x rotation 90 25 z z rotation 0 Ok Sound
18. 02 Page 14 of 43 30 06 2014 Nel EC Contract No FP7 284877 M 9 CALCULATIONS AND RESULTS Once all the previous parameters have been suitably set the software is ready to perform the calculations Go to Calculations gt Calculate to launch them Before running the time increment can be modified here When the waiting figure disappears press the Exit button and then go to Calculations gt View Results to plot the sound pressure quantities Figure 10 Noise levels calculated at each receiver can be plotted one at time as the receiver is selected from the menu on the left The contribution of all the sources together or of several sources subgroups can be viewed The sources are automatically grouped in point sources box sources area sources and rolling noise sources these can be plotted separately In addition the contribution of each single source can be plotted by selecting the vehicle and the source name from the two lists inside the select source panel Two main plotting modes exist time domain and frequency domain In either case the plot is updated when the button update inside the relative panel is pressed The total sound pressure level can be shown as it evolves in time or a single frequency band can be selected and its time evolution plotted In terms of frequency domain plotting the sound pressure level relative to the whole train pass by can be selected L
19. 4877 dm 2007 2013 Fundamental solution for the Fundamental solution for the image source G source G iA Calculate Sound pressure level Lat receiver Get sound power of the source L Figure A 3 Flow chart combination of source and image source A 1 TIME EVOLUTION OF THE SOURCE 0 sO Zso MR Figure A 4 Source red and receiver blue the shaded red dot represents the actual source position at time while the full colour red dot represents the source position at the time of emission of noise received by the receiver at time t At the time instant t the source is located at the position x o Yso zso At this moment the sound reaching the receiver was radiated by the source when it was located at the earlier position x yz These coordinates are defined as ACT WP4 D ISV 022 02 Page 26 of 43 30 06 2014 Nella EC Contract No FP7 284877 M x t xs vt MR x MR y y A 1 Zy t Zs where xs y s Xs are the initial coordinates of the source at time 0 s v represents the train speed M is the ratio between the train speed and the speed of sound c in air Mach number while R is the distance between x y z and the receiver at time t Note that x y z represents a delayed set of coordinates with respect to the actual position of the source xo Yso Zso An expression for R can be obtained as 2 2 2 2 2 CN Mx Mx a M ro tro tx 2309 4X4 A 2 M 1
20. Nel EC Contract No FP7 284877 M APPENDIX A THEORY The noise propagation model is based on image source theory and for the case of pass by simulations accounts for the so called Doppler effect Only one reflecting plane exists which is characterised through an impedance model as described below The train body does not affect the noise pattern in any way so called installation effects are assumed to be accounted for within the source definitions The flow charts of Figure A 1 Figure A 2 and Figure A 3 summarise the steps performed in the software to calculate the noise at a receiver location The formulas for the variables adopted in the flow chart are detailed in the following sections These describe the main theoretical aspects behind the model Attention is focused on the theory of a moving source above an impedance ground The equations relating to standstill calculations can be readily derived from those of the moving source by setting the speed equal to zero Only one source and one receiver are considered in describing the theory The same procedure is valid for any source and for any receiver defined in the model To calculate the total noise at a single receiver the contributions of all the sources are added incoherently The receiver is fixed in time at location x y z ACT WP4 D ISV 022 02 Page 23 of 43 30 06 2014 adiTRAIN EC Contract No FP7 284877 d Get source and receiver coordinates Calculate actua
21. Ns 1 Nr yr repmat yr Ns Nt 1 zr repmat zr Ns Nt 1 Time evolution of source position xs xO0t v t ys y0 zs z0 Time evolution of image sources position yim y0 xim xs zim 2 rh z0 ACT WP4 D ISV 022 02 Page 37 of 43 30 06 2014 adbiTRAIN EC Contract No FP7 284877 al Time evolution of reflection point position if rh zr yrl yr ones size t else A z0 rh zr rh yrl A yrty0 1 A end Yrl yrl yr y0 yr xrl Yrl xr x0 Yrl v t txr zrl rh Acoustic ray from source image sources to receivers rs sqrt yr y0 2 zr z0 2 rim sqrt yr yim 2 zr zim 2 Rs M xr M xs t M 2 rs 2 4rs 2 xr 2 2 xr xs xs 2 1 2 M 2 1 Rim M xr M xim M 2 rim 2 4rim 2 xr 2 2 xr ximt xim 2 1 2 M 2 1 Angle between direction of motion and source receiver axis Betas acos xr xs 4M Rs Rs Betaim acos xr xim M Rim Rim coordinates delayed accounting for distance travelled by acoustic pulse xsdel 2xs M Rs ysdel ys zsdel zs ximsdel xim M Rim yimsdel yim zimsdel zim xrldel xrl Yrl M Rim reflection point on ground yrldel yr1 zrldel zrl SEmission angles phiim atan2 yrldel yimsdel xrldel ximsdel indneg phiim lt 0 phiim indneg phiim indneg 2 pi phis atan2 yr ysdel xr xsdel indneg phis lt 0 phis indneg phis indneg 2 pi Rxyim sqrt xrldel ximsdel 2 yri
22. R NU EM EUN DEMNM NIU SUM PU MM MM I UI NU UM DUME 15 10 File management Rote 16 11 File format for uploading Gala rire rtr bla en oor t abu erac i xrare telnet Eia itin 16 11 1 Sound pOWETS e dae 16 TLIA Single pont SUCE ES 17 INT Area SUCE rms 17 Pieko BOX SOUCO nenen eane e a ee CL ISI UE eee eee 17 11 14 Rolling NGISe SOUMCES ised heen eee 18 11 2 Bus ec tate vnc eastern 19 11 2 1 M nopole to dipol ratio uo oett tret e terocetaiemescctimeeteretenendseherstetumerenuse 19 11 2 2 User defined direclivily ciice certet eese cede iai texte ea cbb KR tira 19 11 3 Frequency dependent aerodynamic coefficient seeees 20 11 4 oso M RU m 21 11 5 Receivers ERI o UM 21 acie M 22 Appendix A Theory Me 23 Ad Time evolution of the Source soxie cetiiccoreisemnenecstoreteserncantseterenereimencarakeuennatwceratetnessebatmeontes 26 A 2 Time evolution of the image source eessssesessseeeenneeneeeeeen nnne nnne 28 CMM Ct T PRETI t T ee ee eee eee eae eee 30 A 4 Sound pressure contribution of the source ssssseeenm 30 ACT WP4 D ISV 022 02 Page 3 of 43 30 06 2014 Neira EC Contract No FP7 284877 M A 5 Sound pressure contribution of the image source ssssssseeee 30 A 6 Total contribution uscsciheeeie cines ebu
23. TION To obtain the total contribution of the two sources the two fundamental solutions are to be added coherently including their relative phase ACT WP4 D ISV 022 02 Page 30 of 43 30 06 2014 Nel EC Contract No FP7 284877 M Ga G G A 19 tot un Finally if L is the sound power level of the moving source expressed in decibels the sound pressure level is calculated by the following equation Wee 2 LL LL 2 G A 20 ref where W 10 watt is the reference for sound power level and p 2x10 Pa is the reference pressure A 7 NARROW BAND CONVERSION OF ONE THIRD OCTAVE BAND INPUT To represent the Doppler effect properly a narrow band frequency resolution is required Input data are given in terms of sound power and are generally available only in one third octave bands Any conversion from one third octave bands to narrow bands is in principle incorrect as the original narrow band information has been lost To allow the possibility of investigating the Doppler effect the software implements a routine that interpolates one third octave band data to obtain a narrow band resolution It comprises the two following steps Firstly one third octave inputs are linearly interpolated to obtain a narrow band resolution Secondly the narrow band result is scaled in such a way that the overall level is not modified by the interpolation when converted back to one third octave bands When calculating the final results a c
24. d When at least one set exists the wheelsets can be added to the vehicle Two modes of adding wheelsets are available standard and one by one The standard mode allows the number of wheelsets existing on the vehicle to be entered and then the bogie wheelbase and bogie centre distance to be specified In this mode only two or four wheelsets can be allocated to a vehicle Note that if two wheelsets are added the software will ignore the bogie wheelbase information ACT WP4 D ISV 022 02 Page 8 of 43 30 06 2014 Nel EC Contract No FP7 284877 dL When pressing the button ok the software asks for the wheelset type that they belong to before updating the vehicle Both the wheelset position and type can be edited using the context menu available when right clicking on each wheelset in the axes see Figure 4 The second mode of adding wheelsets consists in adding them one by one using the button Add wheelset Pantographs can also be added to the vehicle The pantograph to be added at this stage does not represent its acoustic properties but is simply a visualisation on the vehicle image that can help with positioning sources I CreateWagon lau Pan Zoom Rote 0 bez s0 Hide Vehicle Define vehicle geometry Length m 23 Roof height m 4 B Floor height m 1 Width m 3 4r Vehicle name a T 2r oF Wheelsets type Edit Position 3 Create new
25. del yimsdel 2 thim pi 2 atan2 zsdel zrldel Rxyim Rxys sqrt xr xsdel 2 yr ysdel 2 ths pi 2 atan2 zsdel zr Rxys phig pi 2 atan2 zsdel zrldel Rxyim ACT WP4 D ISV 022 02 Page 38 of 43 30 06 2014 ald lTRAN EC Contract No FP7 284877 M 2007 2013 B 2 SOUND PRESSURE CALCULATION f3 third octave band centre frequency ty t c0 34 rho0 pref Wref rain speed Sources sound power matrix NfxNs TO source monopole to dipole ratio third octave to narrow band parameter parameter for narrow band all the sources structure alls isTwins flag for rolling noise sources alls dipAx dipole axis orientation narrow band freq set wheelset typ wlstset allxO0 3 1 25 20e 6 1e 12 if DoppEff M else end Nf le Ns le Nt si Nr si Nf3 1 idx c percm percm percm v c0 0 ngth f0 ngth a115 ze Rs 2 ze Rs 3 ength f3 umsum rep 1 1 structure percm cumsum idx 1 end 1 741 percm permute perem 2 3 4 1 i percm repmat percm 1 Nt Nr 1 percd Rs re Rim r Betas Betai phig phis 1l percm Lwnar reshape Lwnar Ns 1 1 Nf Lwnar repmat Lwnar 1 Nt Nr 1 f0 reshape f0 1 1 1 length f0 f0 repmat f0 Ns Nt Nr 1 pmat Rs 1 1 1 Nf epmat Rim 1 1 1 Nf repmat Betas 1 1 1 Nf m repmat Betaim 1 1 1 Nf repmat phig 1 1 1 Nf repmat phis
26. e summarised as follows see 5 for further details Reflection coefficient for plane waves impinging an absorptive ground z Eng cos Q 1 E z COS P 1 eee The reflection coefficient accounting for the spherical propagation effect is Ry R RF A 31 where F is equal to F 1 iVawexp w erfe iw A 32 and w can be calculated as w Za ti Jk Rin mE A 33 ng A 9 SOURCE CHARACTERISATION In the software any type of source is defined as a group of point sources and each single source is characterised by its acoustic power and directivity The acoustic power of the source is loaded by the user The directivity can be defined in several ways In each case D is a factor applied to the pressure such that the average of D over a sphere is unity Monopole to dipole ratio If the built in functionality for monopole to dipole ratio directivity is used this is based on the following equations D p 43 cos 0 1 p A 34 where pm is the monopole to dipole ratio of the source and 8 is the angle of the source receiver path with respect to the dipole axis Custom directivity To derive the directivity factor D from a set of sound pressure measurements around a sphere enclosing the source the following equation is applied ACT WP4 D ISV 022 02 Page 33 of 43 30 06 2014 Nella EC Contract No FP7 284877 d p 6 9 t 2 A 35 P0 pr sin daig 0 0 9 0 Agr with pl the mean square
27. ection 7 below while roughness can be set via the radio buttons Unit 1 um roughness in each wavelength band TSI the limit curve defined in TSI is adopted Load one file the combined wheel and rail roughness is contained in one single file extension to See section 11 for format explanation e Load two files wheel roughness and rail roughness are loaded separately the software will add them up The same to format file is to be used Note that the sound power levels will not be uploaded until the Attach acoustic power button is pressed 6 TEST SITE DEFINITION To define the test site the Test Site Definition item in the Create menu gives access to the GUI showed in Figure 8 The geometry can be set only in terms of the vertical distance between the main reflecting ground and the top of the rail i e the vertical origin of the reference system The ground can furthermore be defined as rigid or reflecting Delany Bazley Miki and Hamet Berangier impedance models are implemented in the code Calculations without ground can also be performed r ga TestSiteGeometry Ground geometry Ground modelling Select ground geometry Select ground model Delany Bazley mo Ground position m Flow resistivity Pas m 2 0 5 3e 06 Figure 8 Test site geometry and ground impedance properties ACT WP4 D ISV 022 02 Page 13 of 43 30 06 2014 adiTRAIN EC Contract No FP7 284877 M
28. framework for a simple global simulation model based on the minimum requirements and input output data defined in Task 4 1 As input this global simulation tool takes data describing the various sources on a train sound powers possibly directivities along with geometrical data about the sources the receiver and the ground properties From these input data predicts the evolution of the pass by sound level overall and in one third octave bands The development of this simulation tool is based on the required input output defined in Task 4 1 The purpose of this simulation tool is to demonstrate the method of prediction required as part of the virtual certification process so that third parties can use it Full details of the theory implemented in the software are given in an appendix ACT WP4 D ISV 022 02 Page 2 of 43 30 06 2014 Nel EC Contract No FP7 284877 M TABLE OF CONTENTS EXeculive IU NEL a REA EEE EE o o mE 2 Listor Fg ESenco E o T T E 5 1 Introductions serne a a a eee eee ea a 6 CERES 0 RN 6 2 1 Frame of reference EE OO ee S oUm 6 9 JAgdaHhewWVvellele esiti toti a EON P EU UM UND RUM MA SN UNA UII RE 7 31 Add SOUrCES ee ee ee oe ee ere eee ere EE 9 4 Manage the AIA ais see oo oro aeae babere i o RE EEEO are EM SEG RDr a ERE EAEE 11 5 Add rolling MOSS ee E 12 6 WSS Sie se eee t ep 13 MEE Order 2 0 LOO L IEEESEETEEMRM 14 CHEN D 0 or EU Et ETE 14 9 Calculations and resulls i to sat nba plora E A Sa EE t E
29. from the software sssseeeeeeeene 37 BT Geometrical data suene udin ood inet M etu I Mesi ML 37 B 2 Sound pressure CalG UMN xi cic nei an ce cttces ceessestotaicnanteastaatjectteancetidaaeierteateaudeanyaaltecnene 39 B3 Ground INOOSS eoa xia me LINE DNI I ipi 41 ACT WP4 D ISV 022 02 Page 4 of 43 30 06 2014 Nel EC Contract No FP7 284877 M LIST OF FIGURES Figure 1 Frame of reference essit rii dac iieduni udi bun di suae oun uc lume lcu td ED E d tUE 7 Figure 2 Add a new vehicle into the train soi opo annie diene 7 Figure 3 Describing new vehicle parameters eessssessseseeeeeeeeennnnnnennnennn nnn 8 Figure 4 Right click on the wheelset to edit its properties sssessseeeeeee 9 Figure 5 Defining new source parameters eseeeeseeenneeeeneeennenn nennen 10 Figure 6 Right click on the vehicle body to edit all vehicle properties including sources related to ig s ee TL 11 Figure 7 Defining a rolling noise input for a specific wheelset type sseeseseeesssess 12 Figure 8 Test site geometry and ground impedance properties sssseeeesssss 13 Figure 9 Example of receivers position for standstill calculation ssssseeeesss 14 Figure 10 Results view e 16 Figure 11 Face numbering for the box SOUFCe
30. g faces and one non radiating face A 10 POINT SOURCES FOR ROLLING NOISE MODELLING Wheel Two equivalent point sources are used model the noise contribution from each wheel and they are both located at the wheel centre The first one accounts for the acoustic power from radial vibration and has a monopole directivity The second one accounts for the acoustic power from axial vibration and has a dipole directivity with axis in the lateral direction Each wheelset is composed of two wheels and both the wheels are present in the simulation i e there are 4 point sources per wheelset ACT WP4 D ISV 022 02 Page 34 of 43 30 06 2014 Nel EC Contract No FP7 284877 M Rail There are two sources used to model the rail vibration due to the interaction with each wheel The rail vertical vibration contribution is modelled with a point source having a monopole directivity The lateral vibration is modelled with a point source with dipole directivity orientated laterally In ACOUTRAIN there is no distinction between the contribution due to propagating and decaying waves in a given direction which means that when preparing the text file for loading power the noise contribution from propagating and decaying waves should be combined into a single sound power The position for rail sources is 0 07 m below the top of rail Sleeper The sleeper acoustic power is represented by a monopole at 0 2 m below the top of rail directly below the rail No
31. he rail power file the vertical power component comes first and then the lateral one Note that if the rail power has been calculated per wave component then both the propagating and decaying waves should be accounted by adding them There must be only one power component in the sleeper power file ACT WP4 D ISV 022 02 Page 18 of 43 30 06 2014 Nel EC Contract No FP7 284877 dL Wheel power example wheel 315 40 50 63 80 o 10000 0 149 6 149 3 149 0 152 4 155 1 Z 200 0 150 8 1581 164 7 168 9 170 0 200 Rail power example rail 31 5 40 50 63 80 i 10000 0 148 5 159 6 164 6 167 5 171 1 as 200 0 145 6 154 8 158 6 164 5 173 8 200 Sleeper power example sleep 31 5 40 50 63 80 10000 0 143 5 159 6 164 6 167 5 TOI i 200 0 145 6 154 8 158 6 164 5 173 8 200 11 2 DiRECTIVITY 11 2 1 Monopole to dipole ratio The file format for uploading frequency dependent monopole to dipole ratio directivity is the same as in the previous section The identifier is now the string mndp Only the monopole proportion between 0 and 1 should be reported in the second line the dipole one being calculated consequently mndp 25 314 5 40 50 63 ie 10000 0 39 o o o oO o o 11 2 2 User defined directivity Directivity can be described in a text file that gives noise levels sound pressure level in dB arbitrary reference at a given radius for various angles amp see Figure 1 on a sphere centred at the source The identifier string is ud
32. ir The example below shows how the text file has to be prepared ACT WP4 D ISV 022 02 Page 19 of 43 30 06 2014 Nel EC Contract No FP7 284877 d udir radius theta phi 25 31 5 40 50 63 ds 10000 0 2 0 0 50 52 60 55 55 55 0 2 0 30 50 53 54 55 55 ssi 56 0 m T 0 2 180 360 50 m T 255 Again the numbers strings of the text file need to be separated by Tab Note that in this case the actual data directivity data in this case begin from row 2 column 5 The value of the radius in the second column should to be kept the same as it is representative of the radius of a sphere where measurements for directivity are taken In any case the software only keeps the first value and ignores everything after Again the first column after the identifier is not read by the software and can be filled with 0 IMPORTANT e Atthe calculation stage in order to get the directivity in any necessary direction defined by the relative position between the source and receiver the nearest available measurement point is adopted The level of accuracy depends mostly on the amount of measurement points on the sphere compared to the directivity of the source It is up to the user to define a measurement grid which is fine enough to be representative of the actual directivity of the source e t is assumed that measurement data to be loaded into the software have been taken around a sphere Which means that 0 8 z and 0 lt lt 2z in this range the
33. ivated ACT WP4 D ISV 022 02 Page 17 of 43 30 06 2014 Nella EC Contract No FP7 284877 M Figure 11 Face numbering for the box source To summarise a total number of seven rows has always to be present in the file The first one is the frequency vector while the other six are the powers related to faces from 1 to 6 One or more can be inactive The example available below shows a box source having five radiating faces Face number 4 the bottom one is not contributing to noise radiation boxS Face 100 125 160 200 250 is 10000 0 1 TLs 116 78 67 79 01 71 85 75 67 i 51 67 0 2 80 79 87 77 89 25 81 42 83 72 ic 61 62 0 3 71 34 76 20 T9391 T2614 74 94 m 51 72 0 0 71 34 76 20 79 91 72 11 74 94 m 51 72 0 5 71 581 77 36 82 22 73 065 76 37 49 97 0 6 T3252 80 10 84 66 T3213 72 05 50 16 11 1 4 Rolling noise sources As an identifier in the first element of the first column the string wheel rail or sleep should appear Below a vertical vector of zeros can be inserted The first row reports again the one third octave centre frequency values below are the sound power levels In the first column inside the txt file a number is required but it will not be read by the software Writing for example 0 is an allowed option In the wheel power file the first line after the frequency vector must be the contribution of the axial motion while the second line is that of the radial motion An example is available below In t
34. l time evolution of source position x o y o z o Calculate distance between source and receiver at time of emission delayed frame of reference R Calculate delayed time evolution of source position x y z Calculate emission angles 6 9s Em with respect to the delayed source Calculate emission angle with respect to the delayed source for Doppler Effect Calculate Directivity factor D Fundamental solution for the source G Figure A 1 flow chart diagram for the source ACT WP4 D ISV 022 02 Page 24 of 43 30 06 2014 adbbtRAIN Get source and receiver Calculate actual time evolution of image source position Ximo Vimo Zimo Calculate distance between image source and receiver at time of emission delayed frame of reference Rin Calculate delayed time evolution of image source position Xin Y im Zim Calculate emission angles Ain Pin Calculate Directivity factor Din EC Contract No FP7 284877 2007 2013 Calculate actual time evolution of point of reflection on ground X Y e020 Calculate delayed time evolution of point of reflection on ground Xo g Zg Calculate ground reflection angle Ps Calculate emission angle Bim Calculate reflection coefficient Rep Fundamental solution for the image source G Figure A 2 Flow chart diagram for the image source ACT WP4 D ISV 022 02 Page 25 of 43 30 06 2014 chit RAIN EC Contract No FP7 28
35. noise benchmark Data as a function of inverse wavelength in 201g s dB re 1e 6 m 6 25 1 1 0 7 23 7 59 7 96 9 23 9 94 11 8312 7811 169 51 7 74 5 85 4 12 1 74 0 31 2 13 8 45 4 29 5 04 5 57 11 5 RECEIVERS To load in a group of receivers they have to be defined in a text file with element separated by a tab character reporting the receiver name in the first column and the coordinates x y and z other three columns An example is shown below Ri 11 61 1 92 4 28 R2 10 85 2 35 4 28 R3 10 0 2515 4 28 RA 9 14 2 35 4 28 R5 8 39 1 92 42228 ACT WP4 D ISV 022 02 Page 21 of 43 30 06 2014 acbiTRAIN EC Contract No FP7 284877 M REFERENCES 1 D J Thompson G Squicciarini Basic global prediction tool and user manual Deliverable 4 2 for ACOUTRAIN project March 2013 2 N Cuny Report with definition of input output data for each global model Deliverable 4 1 for ACOUTRAIN project March 2012 3 Railway applications Acoustics Measurement of noise emitted by railbound vehicles ISO 30959 2013 International Standard Organisation 4 Electroacoustics Sound level meters EN 61672 1 European Standard 5 Acoustics Determination of sound power levels and sound energy levels of noise sources using sound pressure Precision method for anechoic and hemi anechoic rooms ISO 3745 2012 International Standard Organisation ACT WP4 D ISV 022 02 Page 22 of 43 30 06 2014
36. onversion to third octave band is performed back again In this case the shifted frequency vector of equation A 15 is adopted A 8 GROUND REFLECTION Three different impedance models are available to represent the ground The corresponding equations for the normal specific acoustic impedance z are reported in this section Additionally the ground can be modelled as rigid or it can be absent In this case the reflection coefficient R is set to 1 or 0 respectively Delany and Bazley model According to Delany and Bazley 1 the ground impedance can be obtained as 0 75 0 73 z 14 9 08 peed i11 9 IE A 21 di o o where ais the flow resistivity assuming a time dependence of e If the ground consists of a porous layer of finite thickness L the impedance is modified as Zag iz COt k L A 22 ng With k representing the wavenumber inside the absorbing material obtained as ACT WP4 D ISV 022 02 Page 31 of 43 30 06 2014 Nel EC Contract No FP7 284877 M 0 7 0 59 i k 1s109 202 nof 104 m Oo Oo According to the original work this model should be applied only for 0 01 lt 1 o Miki model A similar model has been proposed by Miki 2 and 3 and is meant to be valid in wider range of flow resistivity This is also available in the software 0 632 0 632 aaia DUO ga SOO A 24 e o o where o is the flow resistivity If the ground consists of a porous layer of fini
37. power Uni Power z 121 E 120 119 5 118 20 to 20k Hz T O 1 x gt train Cancel Ok m Figure 5 Defining new source parameters Different source types are available As a default setting a Point Source is proposed Sound power can be loaded from a file according to the format shown in Section 11 by default a unit power spectrum is proposed e Alternatively the Area Source will distribute point sources on a given area As a third option the user can select the box source model In this case a box is defined in the model and each face can have one source located at its centre radiating in the halfspace exterior to the box In this case the user has to load a different file to define the acoustic power of each face see Section 11 1 3 For all these sources the aerodynamic source option can be chosen In this case a dependence of noise level with speed has to be defined The source directivity is defined in terms of a ratio between monopole and dipole source strengths The monopole to dipole ratio can be modified by the Reset all button in the Standard directivity panel Otherwise a different ratio value can be set for each frequency band by loading an appropriate text file see Section 11 The dipole axis can be modified by rotating it around the x axis and then around z axis from its original position parallel to the z a
38. pressure as measured at distance r from the source and at position 6 9 according to the spherical coordinates of Figure 1 Area source In the area source the loaded acoustic power is spread over a user defined area through 4 x 4 equally spaced point sources If necessary they can have the monopole to dipole ratio type of directivity all sources have the same directivity Aerodynamic source Strictly speaking this is not a type of source but is actually a property that the above defined sources can have or not If the flag aerodynamic source is selected this makes the source speed dependent by a law of type y Ly Lo X en logi mE A 36 Vo where the coefficient X and the reference velocity vo are quantities defined by the user while L o represents the loaded source power associated with the source A widely adopted value for Xaero is 60 This can also be made frequency dependent Box source The box source type is based on the outcomes of WP3 Task 3 1 of the ACOUTRAIN project 6 These sources are useful to define noise radiated from a source of finite size whose radiating body is more like a box than a point One single source radiating as half a monopole into the external domain is located at the centre of a certain number of faces of the box Each source is given an acoustic power loaded by the user and obtained through a postprocessing procedure the details of which can be found in 6 Normally the box has five radiatin
39. r tbs pieni leo b ebur teet nia eb iate std qpipR iesu SUP NU reenn 30 A 7 Narrow band conversion of one third octave band input sssssseeeesess 31 A 8 Ground reflection ETT TETTE 31 Ut d uels rizv deo c 31 Miki WOE Gls er CT H HPT 32 Hamet and Berangier model ssssssseeeeeseeeeeene enne nnne nnn nnne 32 Reflection CoefficieNt Ret T aeea E E EA E EEEE EE 33 A 9 SourechardcteliSallOni s se acere seen xpi eie c Spur E Een PM pM pi ERR SEP EEEiE eenn 33 puse ceme os irciome t T askin 33 Custom directivity ous iio dis xax tha pt uer fadi e she ado ia tea sau ge dias Um Ma DIM IEM EGIT Mts 33 Area SONS essa qr aiuti cRrip eaa i eue dni 2046 Reis douse a Ree rea dU dean trea D Rut aS UE 34 Aerodynamic SOUNCE Per TUER 34 BOX SO UPOB essaie ker rA py RM p M pg pt pg dtp pui Rn qistqud Fu rl naeis E a pr TRIS 34 A 10 Point sources for rolling noise modelling eeeeseseeeeeeeeee 34 PRUDENTER NE TN 34 ze H 35 illl M EREA 35 Other source distriDUlioris ccn terr ne Euer exa nre b e ak ES eb x E Ida Ea Ep 35 References used in Appendix A atem rea US dra SURE PL EXNVEN RN SINE EUESEUREI EEUU t UREERUP RE UE UE 36 APPENDIX B Main calculation routines
40. ssesesesseeeeeeeneneeneeenn enne 18 ACT WP4 D ISV 022 02 Page 5 of 43 30 06 2014 Nel EC Contract No FP7 284877 M 1 INTRODUCTION The present deliverable summarises the outcomes of Task 4 2 The objective of this task was to implement a framework for a simple global simulation model As input this global simulation tool takes data describing the various sources on a train sound powers directivities along with geometrical data about the sources the receiver and the ground properties From these input data it predicts the evolution of the pass by sound level overall and in one third octave bands Deliverable 4 2 1 already described the software in its version VBeta1 7 2013 Meanwhile in order to meet the requirements of the ongoing ACOUTRAIN project some updates have been made to the software The aim of this deliverable is to describe the latest version of the software and to give full details of the theory behind it The main text is principally an update of Deliverable 4 2 appendix A is dedicated to the theory of moving sources above an impedance ground while appendix B reports the most relevant parts of the code The development of this simulation tool is based on the required input output defined in Deliverable 4 1 2 This document corresponds to Version 1 0 of the ACOUTRAIN software released in June 2014 A 32 bit or 64 bit compiled version of the software is provided under a license agreement after installing the 8 0 Matlab
41. te Calculations Edit ViewOptions Help Wo EE Edit Move Copy Mirror Delete List Sources Modei name Not yet saved 2007 2013 Figure 6 Right click on the vehicle body to edit all vehicle properties including sources related to the vehicle The Copy option will copy the vehicle and position it to the right of the existing one ACT WP4 D ISV 022 02 Page 11 of 43 30 06 2014 wcbirrain EC Contract No FP7 284877 M To move a vehicle from its position in a train to another one choose the Move option from the menu and then left click on the gap between two other vehicles where the selected vehicle has to be moved A vehicle can be mirrored relative to the y z plane passing through its centre By choosing the Edit option the window used to create the vehicle is reopened and all the described functionalities are again available The option List sources will again display all the sources and wheelsets of the vehicle 5 ADD ROLLING NOISE The add rolling noise item in the Create menu allows the rolling noise power components to be attached to wheelset types that have already been defined Figure 7 Within this GUI the sound power levels can be visualised in terms of acoustic power If necessary they can be removed from the model n loadRollNoise e Select acoustic power files List of wheelset type N Text fies Loadtext fies V TWINS folder
42. te that this is a standard monopole that radiates in a whole sphere so that it can be reflected in the ground There is one source on each side of the track for each wheelset and the power loaded from the external file is replicated for each of the two sources Other source distributions Other possibilities of source distributions have been studied during the development of the software For the track rail and sleeper an attractive approach is to distribute the sound power along the rail according to the Track Decay Rate It has been observed that in terms of LpAeq Tp there is no significant difference whether the track sources are located just at the wheel rail contact or distributed along the track In terms of the time history of pass by noise the effect is more important This way of modelling track sources will be made available in a future release of the software Similarly several tests have been made to distribute wheel sources over the wheel surface rather than just at the centre Also in this case more options will possibly be made available in future software updates ACT WP4 D ISV 022 02 Page 35 of 43 30 06 2014 adbiTRAIN EC Contract No FP7 284877 M REFERENCES USED IN APPENDIX A 1 M E Delany and E N Bazley Acoustical properties of fibrous absorbent materials Applied Acoustics 3 2 1970 pp 105 116 2 Miki Y Acoustical properties of porous materials Modifications of Delany Bazley models J Acoust Soc Jpn
43. te thickness L the impedance is modified as Zug iz COt k L A 25 ng with km representing the wavenumber inside the absorbing material obtained as 0 618 0 618 en esa 200 maf 102 m Oo Oo im f According to the original work this model can be adopted also for lt 0 01 Oo Hamet and Berangier model A more complex model is also available which accounts for tortuosity h and porosity s as well as flow resistivity It takes its name from the authors of reference 4 1 1 m z E 1 ai 1 E 1 ald i A 27 si ipo ipN ipN where ois the circular frequency p the air density N the Prandtl number set equal to 0 7 and vis taken from the ideal gas law in thermodynamics and is set equal to 1 4 Again if the ground consists of a porous layer of finite thickness L the impedance is modified as Za ng COt k L A 28 The wavenumber inside the absorbing material is obtained as Reference 4 adopts e convention the expression for impedance and wavenumber in the material is here shown with e for consistency with the other models ACT WP4 D ISV 022 02 Page 32 of 43 30 06 2014 Nel EC Contract No FP7 284877 M 1 1 i 2 2 2 Kn 2 p 1 ie 1 oy A 29 c iph ipN ipN Reflection coefficient The equations that relate the ground impedance z to the reflection coefficient Rep are valid for any of the model described above and can b
44. the azimuthal angle and r the distance between the point and the origin ACT WP4 D ISV 022 02 Page 6 of 43 30 06 2014 Nel EC Contract No FP7 284877 M Pi Train velocity Figure 1 Frame of reference 3 ADD A NEW VEHICLE When starting a new model the first vehicle has to be defined and added to the train From the menu bar press Create and then add Vehicle see Figure 2 The window shown in Figure 3 appears B ACOUTRAIN o E sma File Calculations Edit ViewOptions Help a Add vehicle Add rolling noise Test site definition Define operating conditions Define receivers Figure 2 Add a new vehicle into the train ACT WP4 D ISV 022 02 Page 7 of 43 30 06 2014 adbiTRAIN EC Contract No FP7 284877 M r B createwagon pe a R o s o Actions ei Pan Zoom Rotate 3D xz 3D Hide show Vehicle List sources Create new v aris ANY Ib Define vehicle geometry Length m 23 Roof height m 4 Floor height m 1 Width m 3 Vehicle name a 3 Ok Lox Wheelsets type Create new type Radius m Name Create new Available types Edt v Y A Delete r Add wheelsets Pantograph Vehicle Position 1 Add standard bogies Add single wheelset
45. where r represents the distance between the actual position of the source at time and receiver in the vertical plane y z as r a Vso T ES A 3 The angle 5 of Figure A 4 can be evaluated as x X acos AA B A4 S The two angles 8 and related to the source position x y z are A c MM A 5 0 atan S xy R represents the distance between the position x y z and the receiver in the horizontal plane x y R Ja x O y A 6 ACT WP4 D ISV 022 02 Page 27 of 43 30 06 2014 ebl rnuN EC Contract No FP7 284877 M A 2 TIME EVOLUTION OF THE IMAGE SOURCE im tim im Figure A 5 Image source green and receiver blue the green shaded dot represent the actual source position at time while the full colour green dot represent the source position at the time of emission of noise received by the receiver at time At the time instant the image source is located at the position Xino Vimo Zimo At this moment the sound reaching the receiver was radiated by the image source when this was located at the earlier position Xin y z These coordinates are defined as x t xs vt MR x f MR Vim f 9 y A 7 Zim t 2h Zs where Xs Y Xs are the initial coordinates of the source and h is the position of the ground with respect to the axes origin v represents the train speed M is the ratio between the train
46. xis ACT WP4 D ISV 022 02 Page 10 of 43 30 06 2014 Nella EC Contract No FP7 284877 M The directivity can also be described by the user in a text file in terms of noise levels at certain angles and radii in a spherical coordinate system see Section 11 By pressing ok bottom right the current window is closed and the previous one is restored The sources that have been created can be positioned on the vehicle by left clicking on the vehicle axes Once the sources have been positioned a context menu allows their position to be modified they can be switched off on deleted or edited as necessary To help with the right clicking on the sources the vehicle body can be temporarily made invisible All the sources and wheelsets type can be listed with the Source list button top right The procedure of adding sources on a vehicle can be repeated as many times as necessary The vehicle can be saved as a Matlab format file and loaded again for use in other models 4 MANAGE THE TRAIN When all the required wheelsets and sources have been added the vehicle is ready to be placed in the train After entering the vehicle position press the button ok bottom right the current window is closed and the main one restored with the new vehicle available By right clicking on this one several functionalities are displayed the vehicle can be copied edited moved mirrored or deleted see Figure 6 ACOUTRAIN File Crea
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