双燃料发动机活塞热负荷预测研究

Research on prediction of thermal load of piston in dual fuel engine

建立柴油—天然气双燃料发动机工作过程仿真模型,将仿真得到的环境温度和换热系数作为热负荷加载到活塞上,计算得到活塞温度场分布情况,活塞仿真温度值与实测值误差在工程允许范围内,以喷油提前角、替代率、功率、转速、NO_X排放和过量空气系数为自变量,活塞表面最高温度和活塞第一环间平均温度作为因变量,用偏最小二乘回归法建立活塞表面最高温度以及活塞环间平均温度模型。结果表明:NO_X对活塞表面最高温度及活塞环间平均温度影响最大,影响权重分别为0.30和0.31,活塞表面温度检验的最大误差值为5.7%,活塞环间平均温度的最大误差值为7.1%,基本满足工程要求,为双燃料发动机改装提供依据。

The simulation model of diesel-CNG dual-fuel engine is established.Environmental temperature and heat transfer coefficient as heat load are loaded on the piston.The temperature of the piston is obtained by simulation.The error of the simulation temperature and the measured temperature within range of the project.Injection timing,replacement rate,power,rotational speed,NO_X emission and excess air coefficient as independent variables.The maximum temperature and the first ring mean temperature of piston as dependent variables.The model of maximum temperature and first ring mean temperature of piston is established by partial least squares regression method.The results show that NO_X emission is the greatest influence factor on maximum temperature and first ring average temperature of piston,Influence weights are 0.30 and 0.31.The maximum temperature error is 5.7%,the piston ring mean temperature error is 7.1%.Which meet the engineering requirements and provides a basis for the modification of dual fuel engine.