基于SDES方法的翼型动态失速数值模拟研究

Numerical simulation of airfoil dynamic stall based on SDES method

动态失速是航空航天领域中一种普遍存在的流动现象,因气动特性很难预测,对飞行器的性能和飞行安全有着严重影响。为了对机翼动态失速过程中的复杂分离流动进行准确模拟,应用屏蔽分离涡模拟(shielded detached eddy simulation,SDES)方法对NACA 0012翼型的动态失速进行了数值模拟,并与延迟分离涡模拟(delayed detached eddy simulation,DDES)方法进行对比研究。首先验证基于静态翼型的CFD(computational fluid dynamics)模型准确性,随后对动态失速获得的升阻力系数和实验数据进行比较评估,同时分析和量化了动态失速的特征现象,并对动态失速的几个典型阶段进行研究。计算表明:对于静态翼型的分离流动,SDES、DDES方法计算结果相差不大;对于具有强烈流动非定常性的动态失速问题,SDES方法体现了较高的预测准确度,能精细的描述流场及漩涡结构并准确地捕捉到动态失速下复杂流动现象,表现出良好的对于复杂分离流动精确模拟的能力,这对于新型RANS/LES混合方法的应用以及研究翼型绕流机理及相关问题有重要意义。

Dynamic stall is a typical flow phenomenon in the aerospace field.It is difficult to predict the aerodynamic characteristics,which severely affects aircraft performance and flight safety.In order to accurately simulate the complex separation flow during the dynamic stall,shielded detached eddy simulation(SDES)in the RANS/LES hybrid model was used to numerically simulate the dynamic stall of the NACA 0012 airfoil and combined with the delayed detached eddy simulation(DDES)for a comparative study.First,the accuracy of the CFD(computational fluid dynamics)model is verified based on the static airfoil.Then the lift-drag coefficient obtained from the dynamic stall and the experimental data are compared and evaluated,the characteristic phenomena of the dynamic stall are analyzed and quantified,and several typical stages of the dynamic stall are studied.The calculation results show little difference between SDES and DDES methods for the separated flow of static airfoil.For the dynamic stall problem with the strong unsteady flow,the SDES method reflects high prediction accuracy and can finely describe the flow field,vortex structure,and the complex flow phenomenon under the dynamic stall.Moreover,it shows an excellent ability to simulate the complex separated flow accurately.Therefore,it is of great significance for applying the new RANS/LES hybrid method and studying the flow mechanism around the airfoil and related problems.