Estimation of instantaneous exhaust gas flowrate based on the assumption of a polytropic process

Abstract

Estimation of instantaneous exhaust gas flowrate is very useful in engine-related studies such as calculation of crank angle resolved mass flowrates of hydrocarbons, boundary conditions for exhaust gas flow study and so on. The study provides a simple but reasonably accurate tool to calculate the flowrates based on the assumption of a polytropic gas expansion process. The only information needed to calculate the flowrates is cylinder pressure. The polytropic exponent n is obtained from the logarithmic-scale plot of measured cylinder pressure. The calculated instantaneous mass flowrates of the exhaust gas confirm accuracy of within ±5 per cent except for low engine speed, compared with measured intake flowrates. The characteristics of the flowrates also show blowdown and displacement flow regimes typically observed in internal combustion engines.

Keywords

spark ignition engine polytropic process exhaust mass flowrate instantaneous mass flowrate crank-angle resolved mass flowrate displacement flow model gas flowrate blow-down model orifice flow compressible flow

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References

Yoon

K. S.

Lee

J. S.

A numerical and experimental study on the optimal design for the intake system of the MPI spark ignition engines. KSME Int. J., 1996, 10(4), 471–479.

Heywood

J. B.

Internal Combustion Engine Fundamentals, 1988, pp. 231–234 (McGraw-Hill, New York).

Tabaczynski

R. J.

Heywood

J. B.

Keck

J. C.

Time-resolved measurements of hydrocarbon mass flow rate in the exhaust of a spark-ignition engine. SAE paper 720112, SAE Trans., 1972, 81.

Heywood

J. B.

Internal Combustion Engine Fundamentals, 1988, pp. 130–140 (McGraw-Hill, New York).

Lancaster

D. R.

Kreiger

R. B.

Lienesch

J. H.

Measurement and analysis of engine pressure data. SAE paper 750026, SAE Trans., 1975, 84.

Kempinski

Rife

J. M.

Knock in spark ignition engines. SAE paper 810147, 1981.

Taylor

C. F.

Toong

T. Y.

Heat transfer in internal combustion engines. ASME paper 57-HT-17, 1957.

Olikara

Borman

G. L.

A computer program for calculating properties of equilibrium combustion products with some applications to I.C. engines. SAE paper 750468, 1975.

Heywood

J. B.

Internal Combustion Engine Fundamentals, 1988, pp. 679–682 (McGraw-Hill, New York).

10.

Heywood

J. B.

Internal Combustion Engine Fundamentals, 1988, pp. 220–230 (McGraw-Hill, New York).

11.

Galliot

Cheng

W. K.

Cheng

C. O.

Sztenderowicz

Heywood

J. B.

Collings

In-cylinder measurements of residual gas concentration in a spark ignition engine. SAE Trans., 1990, 99(3), 1144–1150.

12.

Caton

J. A.

Heywood

J. B.

An experimental and analytical study of heat transfer in an engine exhaust port. Int. J. Heat Mass Transfer, 1981, 24(4), 581–595.

13.

Caton

J. A.

Comparisons of thermocouple, time-averaged and mass-averaged exhaust gas temperatures for a sparkignited engine. SAE paper 820050, 1982.