Abstract
This paper proposes an approach to improve engine performance of volumetric efficiency of a multi cylinder diesel engine. A computer simulation model is used to compare volumetric efficiency with instantaneous values. A baseline engine model is first correlated with measured volumetric efficiency data to establish confidence in the engine modelâs predictions. A derivative of the baseline model with exhaust manifold, is then subjected to a transient expedition simulating typical, in-service, maximum rates of engine speed change. Instantaneous volumetric efficiency, calculated over discrete engine cycles forming the sequence, is then compared with its steady speed equivalent at the corresponding speed. It is shown that the engine volumetric efficiency responds almost quasi-steadily under transient operation thus justifying the assumption of correlation between steady speed and transient data. The computer model is used to demonstrate the basic gas dynamic phenomena graphically. The paper provides a good example of the application of computer simulation techniques in providing answers to real engineering questions. In particular, the value of a comprehensive analysis of fundamental physical phenomena characterizing engine mass flow is demonstrated.
Highlights
Optimum engine cylinder charging is achieved by breathing of an engine dependent on the design of intake and exhaust systems[1]
Hall K.G. studied the Design optimization of engine induction systems with different optimization techniques and methodology[2] Steady speed volumetric efficiency is widely used as a parameter to characterize engine mass flow, and is a simple measurement to take
Three important conclusions may be drawn from this study: * Comparison between theoretical prediction and experimental measurements for the design of ysection configuration has been satisfactory, proving the validity of the developed model, while providing a sound foundation for engine performance comparisons of the model cases considered. * The quasi-steady assumption, as applied to transient Automotive internal combustion engine volumetric efficiency under full load throttle conditions, is a valid one
Summary
Optimum engine cylinder charging is achieved by breathing of an engine dependent on the design of intake and exhaust systems[1]. Hall K.G. studied the Design optimization of engine induction systems with different optimization techniques and methodology[2] Steady speed volumetric efficiency is widely used as a parameter to characterize engine mass flow, and is a simple measurement to take It is generally assumed in engine management applications that steady speed data is applicable to transient operation i.e. under changing speed and load. This is the so-called ‘quasisteady assumption’ and it is based on the premise that the engine’s mass flow characteristic will pass through a sequence of steady speed states during a transient expedition[3]. Multidimensional modeling of cold flows and turbulence in reciprocating engines have been tried by David Gosman[5]
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