LES和DES在流体动力噪声预报中的适用性分析

Applicability of LES and DES in fluid dynamic noise prediction

分别以静止机翼、螺旋桨和存在动静相互作用的混流泵为研究对象,采用大涡模拟(LES)和分离涡模拟(DES)计算其脉动流场,并预报对应的流动动力噪声.计算结果表明:当预报静止固体壁面对应宽带噪声时,LES精度要高于DES,且LES对应噪声结果与试验值基本一致;螺旋桨作为运动固体边界,基于DES所预报的螺旋桨负载噪声精度与LES相当;混流泵由于存在动静相互作用,使得DES对应的泵总噪声预报结果在中低频段与LES符合较好,但高频差别较大;此外,在泵进口截面叶轮引起的线谱噪声是总噪声的主要贡献者.

The airfoil,propeller and mixed flow pump with blade-stator interaction was taken as the objects,the transient flow was calculated based on large eddy simulation（LES）and detached eddy simulation（DES）,and then the fluid dynamic noise was forecasted.Calculation results show that when predicting the broadband noise of stationary solid boundary,the accuracy of the LES is higher than DES,and the noise result corresponding to the LES is in well agreement with experiment data.As a result of the propeller as moving solid boundary,the accuracy of DES is equivalent to LES on predicting the propeller noise.Because of the blade and stator interaction,the mixed flow pump noise predicted by DES is close to the result of LES in low and middle frequency,but the difference is notable in high frequency,besides,the noise at pump inlet is mainly caused by the impeller.