ANALYSIS OF GAS-DYNAMIC EFFECTS IN COMPACT EXHAUST SYSTEMS OF SMALL TWO-STROKE ENGINES

  • Galindo, J. (CMT Motores Termicos, Universidad Politecnica de Valencia) ;
  • Serrano, J.R. (CMT Motores Termicos, Universidad Politecnica de Valencia) ;
  • Climent, H. (CMT Motores Termicos, Universidad Politecnica de Valencia) ;
  • Tiseira, A. (CMT Motores Termicos, Universidad Politecnica de Valencia)
  • 발행 : 2007.08.31

초록

This article describes a methodology based on experiments and 1D modeling work related to the exhaust system analysis of a small two-stroke engine. The primary goal of this work was to understand how the design criteria of a compact exhaust system influenced the exhaust port pressure, since its evolution controls not only engine performance but also exhaust emissions. On the experimental side, a fully instrumented 50cc two-stroke engine was used to check the behavior of three different exhaust systems. A problem related to instantaneous pressure measurements in unsteady, hot flow was detected and solved during the study. To build the 1D model of the three exhaust systems, experimental information on the steady flow and the impulse test rigs was obtained under controlled conditions in specific facilities. Accurate comparisons between measured and calculated exhaust port instantaneous pressures were obtained from the following different exhaust system configurations: a straight duct, a tapered pipe and the three compact exhaust systems. The last step in the method used this model to analyze the pressure waves inside the exhaust system and detect the influence of the geometric parameters. The results should lead to improvements in the design process of complex compact exhaust systems in two-stroke engines.

키워드

참고문헌

  1. Blair, G. P. and Johnston, M. B. (1970). Simplified design criteria for expansion chambers for two-cycle gasoline engine. SAE Paper No. 700123
  2. Blair, G. P. (1995). Design and simulation of two-stroke engines. R-161 Society of Automotive Engineers, Inc., Warrendale, PA
  3. Chiou, J. S., Chiang, M. S. and Chen, C. K. (1994). Numerical simulation method applied to the multiexpansion exhaust system of a two-stroke engine. Proc. Instn. Mech. Engrs., Part D: J. Automobile Engineering, 208, 281-288 https://doi.org/10.1243/PIME_PROC_1994_208_195_02
  4. Czerwinski, J., Compte, P., Reutimann, F. and Mayer, A. (2006). Influencing (nano)particle emissions of 2-stroke scooters. Int. J. Automotive Technology 7, 3, 237-244
  5. Daneshyar, H. (1976). One-Dimensional Compressible Flow. Pergamon Press. Oxford. New York
  6. Duret, P., Ecomard, A. and Audinet, M. (1988). A new two-stroke engine with compressed air assisted fuel injection system for high efficiency low emissions applications. SAE Paper No. 880176
  7. Huelsse, W. A. (1968). Investigation and tuning of the exhaust system of small 2-stroke-cycle engines. SAE Paper No. 680469
  8. Leighton, S. R., Cebis, M. J., Southern, M. P., Ahern, S. R. and Horner, L. (1994). The OCP small engine fuel injection system for future two-stroke marine engines. SAE Paper No. 941687
  9. Nuti, M., Pardini, R. and Caponi, D. (1997). Fast injection system: PIAGGIO solution for ULEV 2T SI engines. SAE Paper No. 970362
  10. Payri, F., Benajes, J. and Chust, M. D. (1991). Programme pour etude assistee par ordinateur de systemes d'admission et d'echappement de moteurs. Entropie, 162, 17-23
  11. Payri, F., Desantes, J. M. and Torregrosa, A. J. (1995). Acoustic boundary condition for unsteady one-dimensional flow calculations. J. Sound and Vibration 188, 1, 85-110 https://doi.org/10.1006/jsvi.1995.0580
  12. Payri, F., Torregrosa, A. J. and Chust, M. D. (1996). Application of MacCormack schemes to I.C. engine exhaust noise prediction. J. Sound and Vibration, 195, 757-773 https://doi.org/10.1006/jsvi.1996.0460
  13. Payri, F., Desantes, J. M. and Broatch, A. (2000). Modified impulse method for the measurement of the frequency response of acoustic filters to weakly nonlinear transient excitations. J. Acoustical Society of America 107, 2, 731-738 https://doi.org/10.1121/1.428256
  14. Payri, F., Galindo, J., Climent, H., Pastor, J. M. and Gaia, C. (2001). Optimisation of the scavenging and injection processes of an air-assisted direct fuel injection 50cc 2- stroke S.I. engine by means of modelling. SAE Paper No. 2001-01-1814
  15. Richtmayer, R. D. and Morton, K. W. (1967). Difference Methods for Initial-Value Problems. Interscience. New York
  16. Winterbone, D. E. and Pearson R. J. (1992). A Solution of the Wave Equations Using Real Gases. Int. J. Mechanical Sciences 34, 12, 917-932 https://doi.org/10.1016/0020-7403(92)90062-L