Performance Analysis And Improvement Of Intake System Of Aviation Kerosene Piston Engine

Nowadays,the development of aviation kerosene piston engine is of great significance in UAV and military fields.However,due to the combustion characteristics of kerosene and the poor intake environment when the engine works,it puts forward higher requirements for the performance of the intake system.Improving the outlet mass flow and intake uniformity of intake system has become an urgent problem to improve the in cylinder combustion of aeroengine.The intake system of four stroke aviation kerosene piston engine is taken as the research goal to explore its influence on the intake performance of the engine.Through the coupling simulation method,the effects of intake manifold structural parameters and resonator structural parameters on engine intake performance under ground and high altitude conditions are studied.The main results are as follows:(1)The influence of intake manifold structure parameters on engine intake performance is analyzed.Under ground conditions,with the increase of manifold length,the average outlet mass flow,power and torque of the intake system show a decreasing trend,and the intake unevenness of the whole machine has no obvious change,only in the range of 2.391-2.406%.When the length of the manifold is 72 mm,the average outlet mass flow,power and torque have the maximum values,which are 18.71 g/s,67.1 k W and 116.51 N·m respectively,and the power and torque increase by 3.3%.With the increase of the curvature radius of the manifold,the average outlet mass flow,power and torque of the intake system first increase and then decrease,and the intake air unevenness first decreases and then increases.When the radius of curvature is 60 mm,the average outlet mass flow,power and torque of the intake system have maximum values,which are 18.23 g/s,65.39 k W and 113.53 N·m respectively.The minimum value of intake air unevenness is 2.33% at 60 mm,which is 3.16% lower than that of the original machine.When the inlet position of the manifold is changed to the same inlet shared by the manifolds on the same side,the minimum intake nonuniformity of the whole machine is 0.735%,which is 69% higher than that of the original machine,but the average outlet mass flow and dynamic performance of the intake system become worse.In high altitude condition,with the increase of manifold length,the engine intake nonuniformity does not change significantly,and the flight altitude has little effect on the intake nonuniformity.With the increase of the radius of curvature,the intake nonuniformity of the engine decreases first and then increases,and the influence of flight altitude on it is not obvious.After the inlet position of the manifold is changed,the intake air unevenness of the engine is reduced compared with the original aircraft,and the flight altitude has little effect on it..(2)The influence of resonator structure parameters on engine intake performance is analyzed.Under ground conditions,the intake performance of the engine hardly changes with the increase of the length of the resonant cavity,which can be ignored.The length of the original resonant cavity is appropriate.With the increase of the resonator diameter,the average outlet mass flow,power and torque of the intake system increase gradually,and the unevenness of engine intake air decreases gradually.When the diameter of the resonator is 100 mm,the average outlet mass flow has a maximum value of 18.39 g/s,which increases by 14.9%compared with the original machine.The minimum air inlet unevenness is 2.11% in 100 mm,which is 12.3% lower than that of the original machine.After the shape of the inlet pipe of the resonator is changed from a straight pipe to a tapered pipe,the average outlet mass flow of the intake system is increased from 18.12 g/s to 18.20 g/s,an increase of 4.42%,the unevenness of engine intake air is reduced by 0.67%,and the power and torque are increased by 0.42%.After the position of the inlet pipe of the resonant cavity is changed from the side inlet to the middle inlet,the average outlet mass flow of the intake system increases by 0.33%,the intake unevenness of the whole machine decreases by 40.94%,and the power and torque increase slightly.At high altitude,the intake performance of the engine changes little with the increase of the resonator length.With the increase of the diameter of the resonant cavity,the intake nonuniformity of the engine decreases gradually,and the flight height has little effect on it.After the shape of the inlet pipe of the resonant cavity is changed,the intake nonuniformity decreases slightly,and the influence of flight height on it is not obvious.After the position of the inlet pipe of the resonant cavity is changed,the intake nonuniformity decreases,and the flight height has little effect on it.(3)Improvement and performance comparison of intake system.Under the ground condition,after the improvement of the intake system,the intake nonuniformity of the whole machine is significantly reduced,the engine load is reduced by 12.7%,and the average outlet mass flow is increased by 3.37%.The power and torque increase obviously,and the exhaust temperature of each cylinder decreases and is uniform after improvement.At high altitude,the intake air unevenness is significantly reduced after improvement.The flight altitude has little effect on it.