活塞稳态温度与工况关系拟合方案研究

Study on the Fitting Scheme of Second Order Polynomial Between Piston Steady-state Temperature and Operation Condition of Engine

部分负荷工况下的活塞稳态温度是发动机排放的优化计算的重要边界条件。我们对连续工况下活塞稳态温度进行测量,综合分析测试数据,用二次多项式对活塞温度与转速和扭矩的关系进行拟合,计算了中间工况下活塞温度,并就工况选取方案进行研究。结果表明,活塞温度分别随转速与扭矩的增加而呈现明显的增加趋势;二次多项式拟合方法能有效地获得中间工况下的活塞稳态温度,满足大多数工况下的工程计算精度要求,可用于预测未知工况下的活塞稳态温度,也为缸内三维燃烧和排放的活塞侧边界条件的获取提供了有力的支持。选取八个工况点进行拟合最优,拟合工况点应均匀分散,且包含转速与扭矩分别取极限值的四个工况。

The piston steady temperature under partial load condition was an important boundary condition for the emission calculation in cyhnder. This paper measured the piston steady temperature under continuous operation conditions. On account of a comprehensive analysis of test data, the relationship between piston temperature and the speed and torque was fitted by quadratic polynomial, the piston temperature was calculated under the intermediate working condition, and the selection of the working conditions was studied. The results show that the piston temperature increases obviously with the increase of speed and torque; the fitting method of quadratic polynomial can effectively obtain the piston temperature under the intermediate working condition, the method can meet the needs of engineer calculating precision, it can he used to predict the steady-state temperature of the piston under unknown conditions, it also provides a powerful support for the piston side boundary condition of the three-dimensional combustion and emission in cylinder. The eight operating points are selected to get the optimal fitting, the fitting point should be evenly distributed and the four conditions of the limit value taken respectively by speed and torque are included.