【作者】 叶维祥； 耿晨； 罗先武；

【Author】 YE Wei-xiang;GENG Chen;LUO Xian-wu;Beijing Key Laboratory of CO_2 Utilization and Reduction Technology,Tsinghua University;State Key Laboratory of Hydroscience and Engineering,Department of Energy and Power Engineering,Tsinghua University;

【机构】 清华大学二氧化碳减排与资源化利用技术北京市重点实验室； 清华大学水沙科学与水利水电工程国家重点实验室；

【摘要】 空化演化中的空泡脱落伴随着强烈的流动分离,可能诱发水力机械机组振动,噪声以及流道表面破坏。本文考虑流道表面曲率效应,在修正的SST k-ω模型的基础上发展出一种新的部分时均化(MSSTPANS)模型。采用MSSTPANS模型对绕三维NACA66翼型空化流动进行了模拟,并将计算结果与基于SST k-ω以及SST k-ωPANS两种已有模型的预测数据进行比较。结果表明,相比于其他两个模型,MSSTPANS模型能够较准确地预测出三维翼型表面发生的片空化以及云空化周期性演变的过程;MSSTPANS模型能够较准确地预测空泡脱落频率,该频率与实验测量值的相对误差为5.00%。基于涡输运方程进一步分析了翼型表面周期性的空化演变以及诱发的分离流动,发现分离流动在翼型流向上的演变是形成涡拉伸项高值分布的主要原因,而空泡的初生与溃灭会造成涡膨胀项以及斜压扭矩项高值。最后采用能量平衡方程对绕翼型的流动损失进行分析,得到翼型前缘靠近中间展向面上诱发的云空化是形成局部损失的来源,随着空泡逐渐向下游溃灭,局部损失也向下游逐渐传播,直到翼型尾缘处耗散。更多还原

【Abstract】 The cavitation shedding with strong flow separation induces vibration,noise and surface erosion.In this paper,considering the surface curvature effect,a new partially averaged Navier-Stokes model(MSST PANS) based on a modified SST k-ω model is developed,which is applied to evaluate the capability to predict the cavitating flow over the three-dimensional hydrofoil(NACA66),compared with SST k-ω model and and SST k-ω PANS(SST PANS)model.The results show that,compared with the other two models,MSST PANS model predicts the most accurate results on the sheet cavitation and the periodic evolution of cloud cavitation on three-dimensional hydrofoil surface.The cavitation shedding frequency predicted by MSST PANS model is also closer to the experimental data compared with SST PANS model,with a relative error of 5.00%.Further analyses on periodic cavitation evolution and induced separated flow on the hydrofoil surface are carried out using the vorticity transport equation.It is found that the separated flow evolution on the hydrofoil surface is the main reason forming the high value of the vortex stretching term,while the inception and collapse of the cavitating flow cause the high value of the vortex dilatation and vortex baroclinic torque terms.Finally,the energy balance equation is adopted to analyze the flow losses over the hydrofoil.The results depict that the cloud cavitation induced near the leading edge of the middle spanwise section of the hydrofoil is the source of the local loss.With the collapse of the cavitating flow,the local loss propagates downstream gradually and dissipates at the trailing edge of the hydrofoil finally.更多还原