DIRECT NUMERICAL SIMULATION OF TURBINE CASCADE FLOW WITH HEAT TRANSFER EFFECTS

Low-Reynolds number flow has a significant effect on the performance of high-altitude aircraft engines, especially the turbine parts. In this paper, the low-Reynolds number flow around a turbine cascade was numerically simulated by directly solving the two-dimensional compressible Navier-Stokes equations using a finite difference scheme with 7th-order. The flow Reynolds number is 241800 based on the blade chord, and there exists thermal conduction on the turbine blade surfaces. In the time-averaged flowfield, the pressure on the blade surface agrees well with the experimental data. So does the distribution of Stanton number, except in the turbulence region on the suction surface. For the instantaneous flow, the unsteady flow near the entrance of cascade passage is very weak. But, at the trailing edge of the blade, there exists periodical vortex-shedding on both the pressure and suction surfaces. The vortex-shedding makes the total pressure in the cascade passage and the wake varies periodically, and the main frequency in the wake is double of that in the cascade channel. Besides, the distribution of the second order statistic of pulse velocity in the wake is similar to that of the flow around the cylinder.