PREDICTION OF BOUNDARY LAYER TRANSITION IN A HIGH TURNING COMPRESSOR CASCADE AT SUPERCRITICAL FLOW CONDITIONS

摘要

Numerical simulations of the high turning compressor cascade V2 (AP=50° at design) at supercritical flow conditions (up to Ma_1=0.85) have been conducted with an Euler/integral method and a RANS solver. The comparison to the experiments reveals an improved prediction of flow losses by using proper transition modelling. The applied model is able to accurately capture following aspects of boundary layer development: i) leading edge pressure spikes including separation and transition, ii) re-laminarization of a turbulent boundary layer due to a strong acceleration between the leading edge and suction peak and iii) transitional shock/ boundary layer interactions with large separations. Besides the transition phenomena, the development of the fully turbulent boundary layer downstream the shock shows a significant contribution to the prediction accuracy. In this region, the predicted increase of the displacement and momentum thickness is too small for both computational methods, leading to an overestimation of flow turning by ca. 1.5° (or 3% relative to the design turning).