基于蒙特卡洛法的喷管中强非均匀性介质辐射换热问题求解加速策略

The radiative heat transfer in the solid rocket motor nozzle is non-negligible, and the traditional Monte Carlo method is of low simulation efficiency. Most of the existing acceleration strategies are limited to the cases where the radiative properties span one order of magnitude, which is inconsistent with the characteristics of strong non-uniformity in actual nozzles. Therefore, in the case of radiative properties spanning 2~3 orders of magnitude, the acceleration performance of the Weighted Null-collision Monte Carlo method and the Decomposition Monte Carlo method were compared and investigated based on Null-collision Monte Carlo method. A cubic gray case and a cylindrical non-gray case were analyzed respectively. The results show that both the Weighted Null-collision Monte Carlo method and the Decomposition Monte Carlo method can improve computational efficiency when the null-collision extinction coefficient is bigger than 60% of the global maximum, and the radiative properties of control medium is smaller than 3% of the global maximum. Compared with the Decomposition Monte Carlo method, the Weighted Null-collision Monte Carlo method has better acceleration performance, with efficiency improvement in non-gray case up to 14%. An improved axisymmetric mesh localization method was proposed, which reduced the computational time more than 43% in several typical cases.