# APPROXIMATE THEORETICAL ANALYSIS OF THE CYCLE FOR PULSE-TYPE TURBO-CHARGED TWO-CYCLE DIESEL ENGINE

To obtain adjustments, in the case of comparing performances of a turbocharged two-cycle diesel engine operating under different conditions of atmospheric pressure, temperature, scavenging air temperature, maximum combustion pressure or turbine back pressure, we developed a set of approximate theoretical equations for the turbo- charged two cycle diesel engine under the following assumptions. (1) The exhaust gas turbine is treated as a pulse-type, and the exhaust blow down energy is considered as the theoretical exhaust blow down energy multiplyed by a coefficient introduced by the author, called utility coefficient. (2) For the gas flow between the turbine nozzle and the reduced size of the scavenging and exhaust port, the equilibrium relation is considered as the equivalent flow of the gas and the air volume. (3) The gas exchange in the scavenging period is in the middle stage of perfect mixing and perfect alienating; the heat exchange is in the middle of initial scavenging state and the final scavenging state. (4) The cycle in the engine cylinder is treated as a composite cycle. The compression and expansion indices, and constant pressure expansion ratio are determined depending upon the assumption that the pressures of the compression start and end point, in the main combustion agree with those of the real cycle. Moreover, the specific heat of the gas is a function of the gas temperature and the composition. The developed equations of several conditions of the cycles are simulated for comparison by means of a digital computer. And using the calculated results explain how the performance and cycle factors of the engine are affected by such conditions as atmospheric temperature and presure, scavenging air temperature or cooling condition of the air cooler, maximum combustion pressure or fuel injection timing, turbine back pressure or flow passage area of the silencer. At the same time, we investigate the influence of the turbine and the compressor efficiency, and of the turbine nozzle area. The developed equations agreed with actual operating results. The equation can be used for a diesel engine in different conditions or two engines of similar types in different conditions.

• Corporate Authors:

Society of Naval Architects of Japan

23 Shiba-kotohiracho, Minato-ku
Tokyo 135,   Japan
• Authors:
• NAGAI, M