双向涡数值模拟雷诺应力各向异性研究与分析

Research and analysis of reynolds stress anisotropic in bidirectional vortex simulation

以实验数据和理论结果作为参考,探讨基于布茨涅克各向同性假设的RNG k-ε模型、SST模型和各向异性RSM湍流模型在双向涡流数值计算中的适用性,并对不同入射速度下的双向涡流结构进行了比较分析。计算结果表明,基于布茨涅克各向同性假设的RNG模型与SST模型在不同入射速度下均无法得到内部受迫涡、外部自由涡的双向涡流结构,而RSM模型则可以准确得到双向涡流结构。内、外涡分界面处雷诺正应力各向异性特征显著,且随入射速度的提高而增强,最大差值达到了198%,轴线附近流场雷诺正应力各向异性特征相对较弱,但是最大差值依然达到46%,因此基于布茨涅克各向同性假设的湍流模型不适用于涡流冷壁发动机数值模拟研究。

In this paper,simulation results were compared with experimental data and theoretical results. The simulation validity of RNG k-ε model and SST model based on Boussinesq isotropic hypothesis and RSM model in bidirectional vortex were discussed and bidirectional vortex properties in different inlet velocities were analyzed as well. It is pointed out that the RNG model and SST model could not achieve the bidirectional vortex which frees in outer area and is forced in inner space under any inlet velocity based on Boussinesq isotropic hypothesis,while the RSM model simulation results fit the experiment data and theoretical solutions well. In mantle surface of inner vortex and outer vortex,Reynolds stress anisotropy characteristics is significant and is strengthened with the increase of inlet velocity. The biggest difference between normal stresses in x,y,z direction can reach up to 198%. In core flow area close to axial,Reynolds stress anisotropy is relatively weak,but the greatest difference can still reach as large as 46%. Therefore,it is believed that turbulent models based on Boussinesq isotropic hypothesis are invalid in VCCWC simulation.