BMC 法计算航空发动机红外辐射的效率研究

反向蒙特卡罗(BMC)法的计算精度高、适应性强,是计算目标红外辐射特征的常用方法。基于CFD 和IR 综合计算分析的方法,研究了射线步长、射线数、射线携带能量方式等因素对BMC法计算航空发动机红外辐射强度的效率的影响。结果表明:射线步长与喷管出口当量直径比在0.05~0.1的范围内,射线数达到105量级时的计算效率较高;采用射线携带多个波段能量的方法,计算时间可缩短数十倍;通过MPI平台实现了并行计算,进一步缩短BMC法的计算时间,但并行效率随着计算核心的增加而下降。在保证计算精度的前提下,通过合理地选择参数、算法改进和并行计算,提高了计算效率。

Efficiency of aero-engine infrared radiation computation by using BMC method

The Backward Monte Carlo (BMC) method is a common method for calculating the target's infrared radiation signature because of its high accuracy and strong adaptability. Based on general CFD/IR numerical calculation method, the impact of ray discrete step size, ray number, energy carrying method on aero-engine infrared radiation intensity computation efficiency was investigated by using BMC method. The results show that the computation efficiency is high when the ratio of ray discrete step size to equivalent diameter of nozzle exit is between 0.05 to 0.1 and ray's number is more than 105; the computation time can be shortened by dozens of times through ray carrying multiple bands energy method; the computation time of BMC method can be reduced further by parallel computation with MPI platform, but the parallel efficiently will be decreased with increasing the computation core number. In the premise of ensuring the accuracy of the results, the efficiency of infrared radiation computation was improved by reasonable selection of parameters, algorithm improvement and parallel computation.