高雷诺数下水翼涡发放频率预报方法

Prediction method of hydrofoil vortex shedding frequency at high Reynolds numbers

[目的]高雷诺数下水翼绕流问题因其原理复杂、计算困难,一直是水动力领域关注的热点。基于涡量流函数的离散涡(D VM)模型是一种无网格方法,可有效克服数值粘性问题。同时,在涡量集中区分辨率高,可有效模拟高雷诺数流场中的旋涡运动。使用一种随机涡方法对高雷诺数下二维刚性水翼涡发放频率进行预报。[方法]以NACA 66系列水翼为例,与试验数据对比验证其对涡发放频率预报的准确性。应用此方法分析高雷诺数下来流速度及初始攻角大小对水翼涡发放频率的影响规律。[结果]结果表明:涡发放频率会随来流速度呈非线性增加;随着水翼攻角的增加,泄涡尺寸和涡强不断增大,泄涡频率降低。[结论]来流速度和水翼初始攻角对二维水翼涡发放频率有显著影响,可为螺旋桨桨叶二维剖面的涡发放机理探究,甚至全桨的振动噪声预报提供参考。

[Objectives]Flow around hydrofoils under high Reynolds number is always a hot topic in hydrodynamic field due to its complicated principle and difficult calculation.The Discrete Vortex Model(D VM)based on vorticity and stream function formulation is a meshless method,which effectively overcomes the numerical viscous problem.Vortex movement in the flow field with high Reynolds number can also be accurately simulated because of its high resolution in the vortex concentration range.A random vortex method was used to predict the vortex shedding frequency of two-dimensional rigid hydrofoils with high Reynolds number.[M ethods]T aking NACA 66 series hydrofoil as an example,the prediction of the frequency was verified by comparing with the experimental data.In addition,the effects of flow velocity and Angle of Attack(AOA)on the frequency of hydrofoil vortex shedding were also discussed and analyzed.[R esults]T he results show that,the frequency of the vortex shedding increases nonlinearly with the growth of the inflow velocity.And with the increase of the initial AOA of hydrofoil,t he size and strength of the vortex rise up and the frequency of the vortex shedding goes down.[Conclusions]The velocity of incoming flow and the initial AOA of hydrofoil have a significant effect on the vortex shedding frequency of two-dimensional hydrofoils,w hich provide reference for the study on the vortex shedding mechanism of 2D profile of the blade,and even the prediction of the vibration noise of the whole propeller.