Flow measurements in a nozzle guide vane passage with a low aspect ratio and endwall contouring

Most turbine cascade studies in the literature have been performed in strai ght-endwall, high-aspect-ratio, linear cascades. As a result, there has bee n little appreciation for the role of, and added complexity imposed by, red uced aspect ratios. There also has been little documentation of endwall pro filing with these reduced spans. To examine the role of these factors on ca scade hydrodynamics, a large-scale nozzle guide vane simulator was construc ted at the Heat Transfer Laboratory of the University of Minnesota. This ca scade is comprised of three airfoils between one contoured and one flat end wall. The geometries of the airfoils and endwalls, as well as the experimen tal conditions in the simulator; are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow fi eld in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indi cate that the acceleration imposed by endwall contouring and airfoil turnin g is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significant ly from that adjacent to the straight endwall. [S0889-504X(00)01104-1].