An experimental and numerical study was performed on an optimized compressor stator cascade designed to operate efficiently at high inlet Mach numbers (M1) ranging from 0.83 to 0.93 (higher supercritical flow conditions). Linear cascade tests confirmed that low losses and high turning were achieved at normal supercritical flow conditions (0.7<M1<0.8), as well as higher supercritical flow conditions (0.83<M1<0.93), both at design and off-design incidences. The performance of this optimized stator cascade is better than those reported in the literature based on Double Circular Arc (DCA) and Controlled Diffusion Airfoil (CDA) blades, where losses increase rapidly for M1>0.83. A two-dimensional (2D) Navier-Stokes solver was applied to the cascade to characterize the performance and flow behavior. Good agreement was obtained between the CFD and the experiment. Experimental loss characteristics, blade surface Mach numbers, shadowgraphs, along with CFD flowfield simulations, were presented to elucidate the flow physics. It is found that low losses are due to the well-controlled boundary layer, which is attributed to an optimum flow structure associated with the blade profile. The multishock pattern and the advantageous pressure gradient distribution on the blade are the key reasons of keeping the boundary layer from separating, which in turn accounts for the low losses at the higher supercritical flow conditions.
Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: New insights from flume experiments
