Simulation Analysis And Improvement Research For Small Aviation Intake Port Injection Two-stroke Engine

In UAV (Unmanned Aerial Vehicle), the contemporary piston aircraft engine has many advantages, such as the mature and advanced technology, easy control, high speed, bigger power per the unit of cylinder displacement, short development cycle, light weight, low production cost and so on. So it occupies a very important position in the field of the small aircraft engine. At present the use of small air naturally aspirated two-stroke engine can’t satisfy the mission requirements of altitude60008～10000m, flight time more than24h. So the technology of turbocharger is necessary. Now the turbocharger technology has become the most effective means of the high-altitude environment engine to restore its power.According to this engine, the thesis has established the simulation model of the inlet injection two-stroke turbocharged engine and determined the set of the initial parameters. Secondly using the model of turbocharged engine established, the thesis has simulated and analysed the several factors (exhaust energy, scavenging performance and so on), which have effects on the turbocharged engine. The results show that the value of exhaust energy is the main factor to decide whether a turbocharger running normally. Through simulation research, the thesis has cleared about the laws of exhaust back pressure (scavenging performance, scavenging loss) at different altitudes or loads, the laws of matching working points at different altitudes or at different loads.According to quantitative analyses of the several factors, using the model of turbocharged engine, the thesis has studied the technical measures of improving the turbocharged engine’s dynamic property. Through the research of exhaust port (scavenging port) valve timings, the thesis has cleared about the laws of engine performance at different exhaust port (scavenging port) valve timings and obtained a pair of valve timings appropriate for turbocharged engine. Through the research of inlet and outlet geometric dimensioning, the thesis has cleared about the laws of engine performance with different inlet and outlet geometric dimensionings and then obtained a set of inlet and outlet geometric dimensionings appropriate for turbocharged engine.The thesis has established the model of two-stroke GDI engine and two-stroke GDI turbocharged engine, then determined the set of the initial parameters. The thesis has studied on the exhaust energy, power, scavenging coefficient, escape rate and matching working points between engine and turbocharger. Finally thesis has compared and analysed the data with the inlet injection two-stroke turbocharged engine.