Study On Heavy-fuel Mixture Formation Of Light-Weight,Spark-ignition, Two-stroke Engine

In order to improve the safety of fuel reserves and adapt to the requirements of fuel integration, heavy oil has gradually been applied to light-weight high speed two-stroke piston aero engine. In China, similar work is just at the beginning stage. Compared with gasoline, heavy oil has high viscosity, bad evaporation and unfavorable to the formation of mixture, which affected the power performance engine, so the heavy oil mixture formation is one of the key technical in spark ignition heavy oil engine. This thesis analyses the heavy oil mixture formation in high speed two-stroke engine, explores the characterics and regulars of heavy oil mixture formation in different fuel injected approaches.First, This paper established a simulation model of constant volume combustion bomb by using the simulation software Fire, and verified spray models and spray pressure; On that basis, simulate and analyze fluidic atomization of heavy oil and gasoline, obtaine the influence regulars of spray pressure, ambient pressure, air temperature and fuel temperature on fluidic atomization of heavy oil; Besides, through the comparison and analysis fluidic atomization of heavy oil and gasoline, make clear the different fluidic atomization of heavy oil and gasoline.Next, complete the model of HS-700engine and mesh division, determine initial conditions and boundary conditions, construct the characteristic parameters of mixture formation quality. On that basis, research the process of heavy oil mixture formation in the condition of direct injection, analyze influence regulars of fuel injection parameters, engine structural parameters and intake air parameters on air flow and mixture formation quality; The results of the study show that through optimal injection strategy and organizing the moderate air flow help to homogeneous mixture formation.Finally, analyze possible injection strategy in the condition of semi-direct injection, make clear the influence regulars of injection timing and injection direction to fuel losses and distribution. On that basis, research the process of heavy oil mixture formation in the condition of semi-direct injection; Through analysis of simulation results, obtaine the influence regulars of engine structural parameters and intake air parameters on mixture formation quality in semi-direct injection; Besides, through the comparison with direct injection, make clear that the best way of fuel-injected under the different parameter.The research result of this thesis can provide analysis and disposition basis for the research and development of light-weight high speed two-stroke piston engine.