| Drones play a vital role in national security and economic development.In the UAV(Unmanned Aerial Vehicle),its engine occupies an important position.The piston engine can meet the needs of the UAV due to its high power-to-weight ratio and compact structure.In response to the call for the integration of military fuels,changing the fuel of piston engines to kerosene has become a hot research direction.The four-stroke aviation kerosene piston engine as the research object to explore the performance of aviation kerosene piston engine.The test bench was established,tested the load characteristics and speed characteristics of the engine.Using the GT-POWER software established the engine.The simulation calculation model was verified with test data,and the effects of ignition advance angle,air-fuel ratio,compression ratio,the takeoff environment pressure,the take-off environment temperature and the flight altitude on the engine performance were simulated,and the engine performance was improved.The main results are as follows:(1)The effects of ignition advance angle,air-fuel ratio and compression ratio on engine performance are studied.With the decrease of the ignition angle advance angle,the power and torque first increase and then decrease,and the effective fuel consumption rate first decreases and then increases.The power has a maximum value of 54.72 k W at 34 °CA and a maximum value of 95.01 N·m at 34 °CA.The effective fuel consumption rate has a minimum value of 345.44 g/(k W·h)at 34 °CA.As the air-fuel ratio increases,the power and torque increase and then decrease,and the effective fuel consumption decreases and then increases.The power has a maximum value of 52.84 k W when the air-fuel ratio is13.5,and the torque has a maximum value of 91.75 N·m when the air-fuel ratio is 13.5,the effective fuel consumption rate has a minimum value of 353.26 g/(k W·h)when the air-fuel ratio is 15.5.As the compression ratio increases,the power and torque increase,and the effective fuel consumption rate decreases.When the compression ratio increases from 6.5to 12.5,the power increases from 41.94 k W to 58.69 k W,and the torque increases from72.82 N·m to 101.89 N·m,the effective fuel consumption rate is reduced from 424.07g/(k W·h)to 325.98 g/(k W·h).When the compression ratio is in the range of 6.5 to 9,the average growth rate of power and torque is 4.1%,which is greater than the average growth rate of 1.9% when the compression ratio is in the range of 9 to 12.5.(2)The effects of take-off environmental pressure,take-off environmental temperature and flight altitude on engine performance was studied.As the pressure of the takeoff environment decreases,the power and torque decrease regularly,and the effective fuel consumption rate increases.When the takeoff environment pressure decreases from0.11 MPa to 0.05 MPa,the power decreases from 59.12 k W to 13.02 k W.For every 0.01 MPa decrease in the takeoff environment pressure,the power decreases by an average of7.71 k W.The torque increases from 102.64 N·m to 22.61 N·m,when the ambient pressure decreases by 0.01 MPa,the torque decreases by an average of 13.34 N·m.The effective fuel consumption rate increases from 349.76 g/(k W·h)to 535.44 g/(k W·h).As the temperature of the takeoff environment increases,the output power and torque decrease,and the fuel consumption rate increases.When the takeoff ambient temperature increases from 240 K to 340 K,the output power decreases from 54.14 k W to 50.50 k W,the torque decreases from 94 N·m to 87.68 N·m,and the effective fuel consumption rate increases from 420.40 g/(k W·h)to 473.73 g/(k W·h).For every 10 K increase in temperature,the power and torque decrease by 0.69% on average,and effective fuel consumption increases by 1.2% on average.When the flying altitude increases from 0 m to 6 000 m,the output power decreases from 52.22 k W to 11.26 k W,and the torque decreases from 90.67 N·m to19.56 N·m,the effective fuel consumption rate increases from 356.57 g/(k W·h)to 577.80g/(k W·h).(3)The engine improvement and performance analysis.Analyzing the changes in engine performance from the two operating parameters of ignition advance angle and air-fuel ratio.It is found that the ignition advance angle at the optimal operating point is22 °CA and the air-fuel ratio is 13.5.And the power is 53.84 k W,an increase of 2.14 %.The consumption rate is 477.60 g/(k W·h),which is an increase of 6.81 %.The improved knock index is 50.22,which is a decrease of 10.77 %. |
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