超声速混合层中PIV粒子的湍流变动作用研究

对二维超声速气固两相混合层进行双向耦合，研究了粒子图像测速技术（PIV）中示踪粒子对超声速混合层的湍流变动作用。超声速气固两相混合层的气相采用大涡模拟，离散相采用拉格朗日颗粒轨道模型求解。结果表明:与无负载示踪粒子时的超声速混合层相比，小Stokes数示踪粒子在超声速混合层中的布撒减弱了流向湍流，而强化了法向湍流，使雷诺应力峰值增大了9.68%；大Stokes数示踪粒子对混合层的湍流脉动起到了一定的削弱作用，最大雷诺应力值只有无负载时的41.74%。大质量载荷时，大量示踪粒子的运动尾迹抹平了部分法向速度脉动，使最大法向速度脉动只有无负载粒子时的38.63%；中等质量载荷时，超声速混合层的法向速度脉动和雷诺应力峰值与无负载粒子时相近；而小质量载荷时，超声速混合层中心线及其附近的法向速度脉动得到较小的增强，而最大流向速度脉动却被削弱了19.29%。小Stokes数和中等质量载荷示踪粒子对原始无负载粒子时的流场影响相对较小，研究结论对高速流动PIV测试有着重要的参考价值。

Investigation of turbulence modification by PIV tracer particles in a supersonic mixing layer

The turbulence modification by Particle Image Velocimetry (PIV) tracer particles was investigated with the two-way coupling of 2D spatial development supersonic gas-solid two-phase mixing layer. The gas phase coupled with the dispersion phase were simulated by the large eddy simulation and the Lagrangian trajectory model, respectively. It is found that the streamwise turbulence of the mixing layer is weakened, the transverse turbulence of the mixing layer strengthened and the Reynolds stress peak value increased by 9.68% than that of the unladen mixing layer due to the small Stokes particles. However, the root mean square velocity of the mixing layer is weakened by the large Stokes particles, and the Reynolds stress peak value is only 41.74% of that of the unladen mixing layer. The root mean square transverse velocity with the large mass loading is 38.63% of that of unladen mixing layer, and it is partly counteracted by the motion of particles. The root mean square transverse velocity and the Reynolds stress with the middle mass loading are almost equal to those of the unladen mixing layer. The largest root mean square streamwise velocity is reduced by 19.29% whereas the root mean square transverse velocity near the centerline of the mixing layer is increased by the small mass loading. The modification to the turbulence of the supersonic mixing layer under the small Stokes number and middle mass loading condition is smaller than other cases. The study provides important reference for improving PIV experiment in high speed flows.