Russian Federation
student
Insertion losses as the main characteristic that mathematically describes the acoustic efficiency of a noise silencer has been considered. This characteristic shows the reduction of noise generated by its source, in particular by the internal combustion engine’s exhaust system, at the control point as a silencer use result. Has been presented a mathematical description of the insertion losses, and have been considered parameters necessary for calculating this characteristic. Has been demonstrated the analytical dependence of impedance for the sound emission by the exhaust system’s end hole from the coefficient of acoustic waves reflection by this hole. The performed analysis of the widely used formulas for calculating the coefficient of sound reflection by the end hole has showed their insufficient accuracy for project designs performing. Have been proposed calculation dependences providing high accuracy for calculations of the reflection coefficient modulus, and the attached length of the channel end hole without a flange in the entire range of the existence of plane waves in it. It has been shown that the end correction of this hole at ka = 0 is 0.6127, and not 0.6133, as it was mistakenly believed until now in world acoustics. Has been proposed a method for calculation the exhaust noise source internal impedance. This method more accurately, in comparison with the already known ones, describes the acoustic processes in the internal combustion engine’s exhaust manifold, thanks to increases the accuracy of calculation the silencer acoustic efficiency, that allows develop the silencer at the early stages of the design of an automotive internal combustion engine.
engine’s exhaust noise, silencer, insertion losses, impedance for sound emission by hole, end hole’s reflection coefficient modulus, end hole’s attached length, exhaust noise source internal impedance, engine’s exhaust manifold, manifold acoustics impedance
1. M.L. Munjal, Acoustics of Ducts and Mufflers. - N.Y.: Wileyentersscience, 1987. - 328 p.
2. Uno Ingard and Vijay K. Singhal, Effect of flow on the acoustic resonances of an open - ended duct. J. Acoustical Society of America, v. 58 (4), 1975. P. 788 - 793.
3. V.B. Panicker and M.L. Munjal, Radiation impedance of an unflanged pipe with mean flow, Noise Control Eng., 18 (2), 1982. P. 48 - 51.
4. H. Levine, J. Schwinger, On the Radiation of Sound from an Unflanged Circular Pipe // J. Phys. Rev., 1948. V. 73. I. 4. P. 383-406.
5. P.O.A.L. Davies, J.L. Bento Coelho, M.J. Bhattacharya, Reflection coefficients for an unflanged pipe with flow // J. Sound Vibr. 1980. V. 72. I. 4. R. 543-546.
6. A.N. Norris, I.C. Sheng, Acoustic radiation from a circular pipe with an infinite flange // J. Sound Vibr. 1989. V. 135. I. 1. P. 85-93.
7. F. Silva, Ph. Guillemain, J. Kergomard, B. Mallaroni, A.N. Norris, Approximation formulae for the acoustic radiation impedance of a cylindrical pipe // J. Sound Vibr. Elsevier. 2009. V. 332. I. 1-2. P. 255-263.
8. V.V. Tupov, Raschet prisoedinennoj dliny koncevogo otverstija kanala bez flanca pri vypolnenii proektnyh akusticheskih razrabotok [Calculation of the attached length of the end hole of a channel without a flange when performing design acoustic developments]. Bezopasnost' v tehnosfere [Safety in the technosphere]. 2016, I. 2, pp. 69-76. (in Russian).
9. V.V. Tupov, A.N. Mironova, Raschet kojefficienta otrazhenija koncevogo otverstija kanala bez flanca v akusticheskih proektah [Calculation of the reflection coefficient of the end hole of a channel without a flange in acoustic projects]. Bezopasnost' v tehnosfere [Safety in the technosphere]. 2017, I. 3, pp. 34 - 41. (in Russian).
10. A.I. Komkin and N.A. Nikiforow, On the design of automobile exhaust systems. / 5th International symposium Transport noise and vibration. St. Petersburg, Russia, 6-8 June 2000.
11. E. Skudrzyk, The Foundations of Acoustics. Basic Mathematics and Basic Acoustics. Springer-Verlag. Wien, New York. 1971. 920 p.
12. Je.G. Bangojan, Razrabotka metodov i sredstv snizhenija shuma dizel'nyh avtopogruzchikov (na primere avtopogruzchika DV - 1792M). Kand. Diss [Development of methods and means for noise reduction of diesel forklift trucks (on the example of a forklift truck DV - 1792M). Cand. Diss].2007. 267 p. (in Russian).
13. V.V. Tupov, Je.G. Bangojan, Issledovanie akusticheskih harakteristik glushitelej shuma vypuska avtotransportnyh dvigatelej vnutrennego sgoranija [Investigation of the acoustic characteristics of mufflers for the exhaust of motor transport internal combustion engines]. Bezopasnost' v tehnosfere [Safety in the technosphere]. 2013, I. 4, pp. 30-35. (in Russian).
14. M.L. Kathuriya, M.L. Munjal, Experimental evaluation of the aeroacoustic characteristics of a source of pulsating gas flow. J. Acoust. Soc. Am., 65 (1), 1079. P. 240-248.
15. J.K. Vennard and R.L. Street, Elementary Fluid Mechanics (S.I. Version), 5th ed., Wiley, New York, 1976, Chap.9.
16. A. Mann, R. Nair, J. Gill, B. Birschbach, et al., Flow Noise Predictions for Single Cylinder Engine - Mounted Muffler Using a Lattice Boltzmann Based Method. SAE Int. J. Engines, 2017, 10 (4). P. 2067-2076.
17. A. Mann, M. S. Kim, B. Neuhierl, et al., Exhaust and Muffler Aeroacoustics Predictions using Lattice Boltzmann Method (J), SAE Int. J. Passeng. Cars - Mech. Syst. 2015, 8 (3). P. 1009-1017.
18. O.I. Polivaev, A.N. Kuznetsov, A.N. Larionov, Reduction of external noise of mobile energy facilities by using active noise control system in muffler. IOP Conference Series: Materials Science and Engineering, 2018, V. 327.
19. W. Elsahar, T. Elnady, Measurement and simulation of two-inlet single-outlet mufflers. SAE International Journal of Passenger Cars-Mechanical Systems, 8, 2015. P. 1026-1033.
20. M. Dixit, V. Sundaram, Optimization of Muffler Acoustics Performance using DFSS Approach. SAE International in United States. World Congress and Exhibition. Technical Paper, 2016-01-1292.
21. L. Xiang, S. Zuo, X. Wu, J. Liu, Study of multi-chamber micro-perforated muffler with adjustable transmission loss. Applied Acoustics. V. 122. 2017. P. 35-40.
22. J. H. Ma and P. Guo, Analysis of Performance of Automotive Exhaust Muffler Based on ANSYS Finite Element, Applied Mechanics and Materials. Vol. 509. 2014. P. 118-122.
23. A. R. Da Silva, P. H. Mareze, A. Lenzi, Approximate expressions for the reflection coefficient of ducts terminated by circular flanges // J. Braz. Soc. Mech. Sci. & Eng. Rio de Janeiro. V. 34. I. 2. 2012. R. 1- 13.
24. J. Xin, Y. Zhang, Study on Acoustic and Fluid Characteristics of Exhaust Muffler WSEAS Transactions on Acoustics and Music. V. 4, 2017. P. 43-51.
