LIU Zhi-gang, YE Jian, ZOU Zheng-ping. Large-eddy simulation of separated boundary layer transition in low-pressure turbine cascade with and without wakes[J]. 2013, 28(12).
LIU Zhi-gang, YE Jian, ZOU Zheng-ping. Large-eddy simulation of separated boundary layer transition in low-pressure turbine cascade with and without wakes[J]. 2013, 28(12).DOI:
A well validated large-eddy simulation (LES) solver for compressible flows was employed to simulate the low pressure turbine (LPT) cascade T106D-EIZ where the Reynolds number and Mach number were 60154 and 0.402
respectively. Two cases with steady inflow and periodic wakes inflow were calculated and analyzed. The results of steady inflow case show that large separation bubble appears at the rear part of the blade suction surface and transition process of the separated shear layer is dominated by Kelvin-Helmholtz (K-H) instability. In the wakes inflow case
due to the periodic sweeping of inflow wakes
the size of time mean separation bubble significantly reduces and the total pressure loss of the cascade also decreases. The analysis of phase averaged and instantaneous flowfield reveals that the negative jet of wake-induced forces the separation point to move forward and then the roll-up vortex emerges. The strong interactions of sweeping negative jet and roll-up vortex result in large aerodynamic losses. Then roll-up vortex quickly breakdowns and boundary layer transitions to turbulence.