转静子交界面处理方法和湍流模型对压气机数值计算影响研究

发布时间：2018-04-30 13:18

本文选题：NASA + Stage　；参考：《南昌航空大学》2016年硕士论文

【摘要】：随着计算流体力学的不断发展,越来越多的转静子交界面处理方法和湍流模型被应用于叶轮机械的数值计算中,然而不同的转静子交界面处理方法和湍流模型对叶轮机械数值计算精度具有较大的影响。本文以NASA Stage 35轴流式压气机为研究对象,在考查网格密度对计算精度影响的基础上,选取合适的网格密度开展了不同转静子交界面处理方法和湍流模型对压气机的数值计算影响的研究。在转静子交界面处理方法的对比分析中,对NUMECA新推出的二维无反射处理方法与常用的周向守恒型连接面和完全非匹配混合面处理方法进行了对比,探讨了三种混合平面法对NASA Stage 35压气机数值模拟的影响,结论如下:(1)对于绝热等熵效率的预测,二维无反射相对于周向守恒型连接面和完全非匹配混合面更接近实验值;对于总压比的预测,在靠近峰值效率点附近二维无反射预测精度高,而在失速工况附近二维无反射预测精度相对较低。(2)对比静子出口总压、总温、相对气流角和相对马赫数沿径向分布的计算精度,周向守恒型连接面和完全非匹配混合面预测效果相一致,但精度低于二维无反射计算结果。(3)对于交界面两侧总温和总压的径向分布预测,三种混合平面法都不能保证总压和总温的守恒,但是上、下游的总压和总温变化很小。(4)通过子午面熵云图和转子、静子中间截面熵值的径向分布对比分析得到,周向守恒型连接面和完全非匹配混合面熵值变化相一致,二维无反射熵增最小,说明二维无反射预测NASA Stage35压气机带来的损失小。(5)通过叶根、叶中以及叶尖截面的相对马赫数云图对比分析,发现在叶根和叶中截面上,三种方法精度一致;但在叶尖截面上,周向守恒型连接面预测的转子叶片吸力面气流分离更明显,完全非匹配混合面在下游静子通道内相对马赫数等值线更密集。在湍流模型对压气机的数值计算影响方面,研究了Baldwin-Lomax、Spalart-Allmaras、K-epsilon(Extend Wall Function)、K-epsilon(Low Re Yang-Shih)、Shear Stress Transport(SST)和EARSM六种湍流模型对NASA Stage35压气机数值模拟的影响,结论如下:(1)通过阻塞点、峰值效率点、失速点三种典型工况下的流量、总压比和绝热等熵效率计算结果的对比分析可知,不同工况下各个湍流模型预测精度不同,无法确定NASA Stage35压气机数值模拟的最佳湍流模型。(2)从阻塞点到失速点的多工况计算结果表明,Spalart-Allmaras模型和SST模型计算精度相对较好。(3)通过对阻塞点、峰值效率点、失速点三种典型工况下径向性能参数分析可知,SST模型计算精度总体上好于Spalart-Allmaras模型。(4)通过对近失速工况下0.99叶高处相对马赫数云图对比分析可知,Baldwin-Lomax模型预测的激波强度最强,K-epsilon模型预测激波强度较弱;六种湍流模型在转子近压力侧和靠近转子、静子尾缘处都出现了低能区,其中Baldwin-Lomax、SST和Spalart-Allmaras较小,K-epsilon模型低能区范围最广。(5)通过对近失速工况下转子吸力面极限流线图对比分析可知,K-epsilon(Low Re Yang-Shih)模型在叶顶发生了完全分离,而其他五种模型在叶顶处发生了分离,但流动很快再附。
[Abstract]:With the continuous development of computational fluid mechanics, more and more hydrostatic interface treatment methods and turbulence models have been applied to the numerical calculation of turbomachinery. However, different hydrostatic and stator interface treatment methods and turbulence models have great influence on the numerical accuracy of turbomachinery. In this paper, the NASA Stage 35 axial flow compressor is used in this paper. For the research object, on the basis of examining the influence of grid density on the accuracy of calculation, the influence of different rotor interface treatment methods and turbulence models on the numerical calculation of the compressor is carried out by selecting suitable grid density. In the comparison and analysis of the treatment method of the stator cross interface, the new two-dimensional non reflective processing side of NUMECA is introduced. The method is compared with the commonly used circumferential conservation and completely unmatched mixed surface treatment methods, and the influence of three kinds of mixed plane method on the numerical simulation of NASA Stage 35 compressor is discussed. The conclusion is as follows: (1) the prediction of adiabatic isentropic efficiency, the two dimensional non reflection is relative to the circumferential conservation type and the completely unmatched mixture surface. It is close to the experimental value; for the prediction of the total pressure ratio, the accuracy of the two-dimensional non reflection prediction near the peak efficiency point is high, while the two-dimensional non reflection prediction accuracy near the stall conditions is relatively low. (2) the calculation accuracy of the total pressure, the total temperature, the relative air angle and the relative Maher number along the path distribution, and the circumferential conservation type connection surface and complete comparison. The prediction results of the mismatched mixed surface are the same, but the accuracy is lower than the two dimensional non reflection calculation results. (3) for the radial distribution of the total pressure on both sides of the interface, the three mixed plane methods can not guarantee the conservation of the total pressure and the total temperature. However, the total pressure and total temperature change in the lower reaches are very small. (4) through the meridian entropy cloud and the rotor, the stator is in the stator. The comparison and analysis of the radial distribution of the entropy value of the cross section shows that the circumferential conservation type connection surface is in accordance with the entropy change of the completely unmatched mixed surface, and the two-dimensional non reflection entropy increase is the smallest, which indicates that the loss of the two-dimensional non reflective prediction NASA Stage35 compressor is small. (5) the comparison and analysis of the relative Maher number of the leaf tip and the leaf tip cross section by the leaf root, the leaf root, the leaf tip section and the leaf tip section are compared and analyzed. The accuracy of the three methods is the same on the cross section of the leaf root and leaf, but on the tip section, the flow separation of the suction surface of the rotor blade is more obvious, and the relative Maher number of the completely unmatched mixed surface is more dense in the downstream stator channel. The effects of Baldwin-Lomax, Spalart-Allmaras, K-epsilon (Extend Wall Function), K-epsilon (Low Re Yang-Shih), Shear Stress and six turbulence models on the numerical simulation of compressor are concluded as follows: (1) flow, total pressure ratio and adiabatic ratio of three typical operating conditions through blocking point, peak efficiency point, and stall point. The comparison analysis of the results of the isentropic efficiency shows that the prediction accuracy of the turbulence models under different working conditions is different, and the optimal turbulence model of the NASA Stage35 compressor numerical simulation can not be determined. (2) the calculation results from the blocking point to the stall point show that the calculation precision of the Spalart-Allmaras model and the SST model is relatively good. (3) through the resistance to the resistance. The analysis of the radial performance parameters in three typical working conditions of the peak efficiency point and the stall point can be seen that the calculation accuracy of the SST model is better than that of the Spalart-Allmaras model. (4) it is known that the intensity of the shock wave of the Baldwin-Lomax model prediction is the strongest and the K-epsilon model is predicted by the contrast analysis of the Maher number at the height of the 0.99 leaves at the near stall condition. The wave intensity is weak; the six turbulence models have low energy areas at the near pressure side and the rotor near the rotor and the stator and tail edge of the rotor, of which Baldwin-Lomax, SST and Spalart-Allmaras are smaller, and the K-epsilon model low energy area is the most widely. (5) K-epsilon (Low Re Yang-Shih) is known by the comparison and analysis of the limit streamline diagram of the rotor suction surface under the near stall conditions. The model completely separated at the top of the leaf, while the other five models were separated at the top of the leaf, but the flow soon reattached.

【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V233

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