An Experimental and Analytical Investigation of the Gas Exchange Process in a Multi-Cylinder Pressure-Charged Two-Stroke Engine

Abstract

The results are given of a comprehensive investigation of the pressure and temperature diagrams in a multi-cylinder two-stroke engine during the gas-exchange process. A six-cylinder turbocharged two-stroke diesel engine was fully instrumented to record transient pressures in three cylinders, in the scavenge belt, and in a number of positions in a specially designed exhaust pipe. Transient-temperature records were taken in the exhaust pipe. Steady-flow tests were carried out on the inlet ports, the exhaust valves, and the exhaust pipe. The steady-flow data were then used in a computer programme (see references (9) (12)‡) to predict the pressure in the cylinder and the pressures and temperatures in the exhaust pipe. Discounting some measured cylinder-pressure records, which were suspect, the investigation showed good agreement between the predicted and measured pressures in the cylinders and exhaust pipe. The analysis of the temperature records showed there was evidence of mixing and longitudinal heat transfer in the exhaust pipe; however, the mean computed temperature in the exhaust pipe at the nozzle end agreed with the measured temperature. Comparison of the measured and computed mass flows at the nozzle end of the pipe using the theoretical diagrams gave good agreement. It was concluded that the computer programme was a satisfactory method for calculating the pressures in the cylinder and exhaust pipe during the gas-exchange process.