Study On Combustion Performance Of A High Power Gasoline Aviation Piston Engine

Due to the advantages of high power-to-weight ratio,high reliability,good economy and simple structure,the piston engine is adopted by most UAV(unmanned aerial vehicle)at home and abroad,but the vast majority of aviation piston engine oil supply system uses a carburetor type,with the improvement of UAV mission requirements,carburetor type piston engine can not meet the demand of flight,so the application of electronic control fuel injection type aviation piston engine is of great significance to improve the power performance and fuel economy of UAV.In this paper,the effects of spark advance Angle,compression ratio,excess air coefficient and other parameters on the performance of an aviation gasoline piston engine were studied by numerical simulation and bench test.Firstly,a corresponding engine test bench system was built based on the electric injection aircraft piston engine,and the load characteristic,speed characteristic and universal characteristic tests of the engine were carried out.Secondly,a one-dimensional simulation model of the electric injection aircraft piston engine was established based on GT-POWER software,and the accuracy of the model was verified by using the test data.Finally,the effects of spark advance Angle,excess air coefficient,compression ratio and intake manifold structure on engine performance were analyzed by using the model without changing other engine parameters.The main conclusions are as follows:(1)Engine bench performance tests were carried out and the following conclusions were drawn: The effective fuel consumption rate of the engine reaches the minimum of278.9g /(k W·h)at 5500 r/min and 85 k W,and the engine has good economy and power performance under high speed and high load.However,when the engine does oblique climb,hover and level flight,the engine needs to be in a high load working state of 5500r/min and 73～100 k W for a long time.At this time,the engine economy is not the best and needs to be improved.(2)The influence law of engine electric injection parameters on engine performance is studied and analyzed.The results show that when the engine speed is 5500 r/min and the spark advance Angle increases from 10 °CA to 36 °CA,the engine power and torque both increase firstly and then decrease.When the spark advance Angle is 28 °CA,the engine power and torque reach the maximum simultaneously.105.05 k W and 182.39 N·m,respectively.The effective fuel consumption of the engine decreases first and then increases with the increase of the spark advance Angle.When the spark advance Angle is26 °CA,the effective fuel consumption of the engine has the minimum value of 266.06g/(k W·h),and the fuel economy is the best.When the engine speed is 5500 r/min,the spark advance Angle is 28 °CA,and the excess air coefficient increases from 0.8 to 1.1,both engine power and torque first increase and then decrease with the increase of the excess air coefficient.When the excess air coefficient is 0.92,The maximum power torque of the engine reaches 105.7k W and 183.5N·m,respectively.The effective fuel consumption decreases monotonically with the increase of excess air coefficient.When the excess air coefficient is 1.1,the effective fuel consumption of the engine has the minimum value of 216.88 g /(k W·h).When the engine speed is 5500 r/min,the spark advance Angle is 28 °CA and the excess air coefficient is 0.92,the engine power and torque increase greatly with the increase of the compression ratio.When the compression ratio increases from 8 to 14,the engine power increases from 101.56 k W to 112.83 k W.The engine torque increases from 176.33 N·m to 195.9 N·m,an increase of 19.57 N·m.As the compression ratio increases from 8 to 14,the effective fuel consumption of the engine decreases from 238.9 g/(k W·h)to 213.23 g/(k W·h),a decrease of 25.67g/(k W·h).(3)The influence of intake manifold length on engine performance is studied and analyzed.The results show that when the length of the intake manifold increases from 300 mm to 410 mm,the engine power and torque first increase and then decrease with the increase of the intake manifold length.When the length of the intake manifold is 370 mm,the engine power and torque reach the maximum values of 105.7 k W and 183.52 N·m,respectively.The effective fuel consumption rate of the engine first increases and then decreases with the increase of the intake manifold length.When the intake manifold length is 380 mm,the effective fuel consumption rate of the engine has the maximum value of229.57 g/(k W·h).