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首页> 外文会议>AIAA/ASME/SAE/ASEE joint propulsion conference exhibit >Improved Prediction of Flow Separation in Thrust Optimized Parabolic Nozzles with FLUENT
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Improved Prediction of Flow Separation in Thrust Optimized Parabolic Nozzles with FLUENT

机译：用FLUENT改进推力优化抛物线形喷嘴中流动分离的预测

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Accurate numerical simulation of separated flows in contoured rocket nozzles is challenging because of the complex flowfield phenomena, in which turbulence has a major role, that develops (shock-pattern, shock-boundary layer interaction, high-speed shear layers and vortices, fluctuations). Hence, turbulence modeling is a key aspect for success in the simulations, specifically for the accurate prediction of shock-induced flow separation, as it is stressed by the failure of many existing turbulence models intended for engineering applications. In this work, the assessment of turbulence modeling with the commercial CFD code FLUENT is investigated. Validation results with separated cold gas flow in Thrust-Optimized Parabolic nozzle using the Spalart-AUmaras (SA) and the Shear Stress Transport (SST) turbulence models are compared in axisymmetric steady-state simulations carried out for the DLR-PAR subscale nozzle. The comparison with experimental data shows that the standard SST model yields more accurate results than the SA model, albeit still predicts an earlier separation location to some extent. The present study suggests tuning of the major coefficients in the eddy-viscosity equation of the SST model in order to improve the predictions, by matching the wall pressure distributions with the measurements. Simulations with a new modification included in the SST model have been carried out for the DLR.-PAR nozzle. They reveal that the modified SST model predicts a closer location of flow separation, in better agreement with the experiments, for the range of nozzle pressure ratios analyzed.
机译：由于复杂的流场现象在湍流中起主要作用，因此在精确的数值模拟中，轮廓波状的火箭喷嘴中的分离流动具有挑战性（湍流模式，激波边界层相互作用，高速剪切层和涡旋，波动）在其中发展。 。因此，湍流建模是仿真成功的关键方面，尤其是对于激振引起的流分离的准确预测，因为许多现有的工程应用湍流模型的失败都给湍流带来了压力。在这项工作中，研究了使用商用CFD代码FLUENT对湍流建模进行评估。在对DLR-PAR超小型喷嘴进行的轴对称稳态模拟中，比较了使用Spalart-AUmaras（SA）和剪切应力传递（SST）湍流模型在推力优化的抛物线形喷嘴中分离的冷气流的验证结果。与实验数据的比较表明，标准SST模型比SA模型产生的结果更准确，尽管仍然可以预测到更早的分离位置。本研究建议通过将壁面压力分布与测量值相匹配来调整SST模型涡流粘度方程中的主要系数，以改善预测结果。对于DLR.-PAR喷嘴，已经进行了SST模型中包含的新修改的模拟。他们发现，对于所分析的喷嘴压力比范围，修改后的SST模型可预测更接近流分离的位置，与实验更好地吻合。

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