The energy content of exhaust pulses in the exhaust system of a supercharged two-stroke-engine model

Abstract

The paper describes a theoretical and experimental investigation of the factors which influence the magnitude of the energy content of the exhaust pulses in the exhaust system of a turbo-charged two-stroke-cycle engine. The theoretical analysis is first concerned with the development of an expression for assessing the energy content of the exhaust gas, and the concept of continuous mean power is described. The influence of wave action on the continuous mean power is then examined using the method of characteristics. The theoretical analysis showed that there is an optimum value for the turbine nozzle area and the exhaust-pipe size to obtain the maximum available power in the exhaust gases. The analysis showed that the power available in the exhaust pulses increased with an increase in engine speed, release pressure and supercharge period, and a decrease in pipe cross-sectional area and nozzle area. In the case of the last two variables, there was an optimum size below which there was a decrease in available power. The experimental programme covered a wide range of speeds, release pressures and exhaust-pipe-nozzle sizes. The results agreed with the qualitative trends predicted in the theoretical analysis.