叶栅流场尾迹中非定常涡系的数值模拟

叶栅通道内包含复杂非定常流动特征的涡系结构，二维直叶栅的尾迹涡系中粘性、尺寸效应十分明显，进行数值模拟时计算量较大，因此时分离涡产生与脱落过程的准确、清晰的捕捉要求有更高效率的数值解法。应用隐式格式、全场统一时间步长和Baldwin—Lomax紊流模型求解二维Navier—Stokes方程，时二维直叶栅流场非定常涡系进行了数值模拟分析，在大攻角、不同进口马赫数的2种工况下，通过对比分析不同时刻叶栅流场的熵和压力瞬态图，捕捉到分离涡产生与脱落过程，并合理地反映了紊流流动特征。通过计算结果看出，所采用的非定常粘性流动数值模拟方法有效，计算效率较高，能够较好地捕捉复杂的尾迹非定常涡系，较为清晰地反映叶栅流场涡系的形成、发展和消失过程，为进一步研究孤立转子和多叶排环境下的非定常流动效应提供了初步的基础。

Numerical Simulation of Unsteady Vortex in the Wake of Cascade Flow

Vortex usually exists in cascade passage due to complex unsteady viscous flow; It requires the high efficiency numerical method to capture the generation and shedding of vortex. A high resolution nonoscillatory scheme and LU-SGS implicit algorithm with Baldwin-Lomax algebraic turbulence model are employed to solve two dimensional Navier-Stokes equations. The numerical study of unsteady vortex in two dimensional cascades is provided. Vortex separation and shedding with different inlet Maeh numbers are captured through the analysis of instantaneous entropy and pressure contours, which can reasonably indicate the mechanics of turbulence flow. The calculations show that the method plays an important role in numerical simulations of unsteady viscous flow; the generation, development and disappearance of vortex are described clearly by numerical simulation; our method of simulation can be used for investigating the effect upon isolated rotor and multi-row blade with tip clearances.