Optimization Design Of Combustion Chamber For Piston Aviation Kerosene Engine

The ignited piston-aviation kerosene engine is widely used in military and civil fields because of its small size,light-weight,high power,simple structure,and easy maintenance.However,kerosene has high kinematic viscosity,poor volatility,and is difficult to ignite.Characteristics have always restricted the improvement of power and economy of aero engines.Therefore,this article focuses on this key issue,and optimizes the design of the combustion chamber of the ignited piston aero-engine,studies its combustion characteristics,and explores structural solutions to improve the performance of aero-kerosene engines,which has important reference value for engineering applications.This article is based on an ignited low-pressure air-assisted direct-injection aero engine.The AVL-Fire software is used to simulate and analyze the three combustion chamber schemes.The motion patterns of each scheme,the turbulent kinetic energy in the cylinder,and the distribution of the mixture are compared and analyzed.In addition,in view of the combustion instability of low-speed and small-load and high-speed and large-load conditions of aero-engines,relevant combustion optimization experiments were carried out.1)Both scheme 1 and scheme 2 can improve the quality of the mixed gas.The design form of scheme 2 can greatly enhance the airflow movement in the cylinder at the beginning of the intake stroke,when the airflow is large and the gas flow rate is high.And promote the rapid evaporation of fuel in the early stage of the intake stroke,thereby forming a more uniform ignition timing The mixture is distributed,and a rich mixture can be formed near the main and auxiliary spark plugs,which is beneficial to improving the combustion quality.In addition,by optimizing the local structure near the valve seat,the direction of the intake airflow can be used to guide the airflow into the cylinder along the wall of the combustion chamber and the cylinder wall.Multiintake energy,so that the turbulent kinetic energy in the cylinder is higher,fuel evaporation is promoted,and the distribution of the2)For the low speed with small load and high speed with large load working conditions,the cycle change rate of scheme 2 is greatly reduced compared to the original machine scheme.While both are better with the advance of EOIT,but the combustion stability of low speed small loads as the ignition angle increases and becomes better,high speed and large load will become worse.The histogram and probability density distribution function are used to analyze the change of combustion conditions in the cylinder with the combustion law of EOIT when the minimum cycle changes the advance angle.Among them,when EOIT of the low speed with low load is 240 ° CA BTDC,the phase of CA50 mostly falls within the range of 4 ° CA BTDC～ 16 ° CA BTDC.At this time,the combustion is best,and the heat radiation is 880 KJ/ m~3 ～ 920 KJ / m~3,the combustion heat release is greatly increased.At high speed with high load,the power increases with the advance of EOIT.