A large-scale, two half-blade facility that simulates a turbine cascade flow is introduced. The advantage of this simulator is that the features of the secondary flow are large, the flow is easily accessible with probes and one can easily change the cascade geometry, such as angle of attack, pitch and aspect ratio in this simple configuration. The main characteristics of the three-dimensional flow near the endwall of a turbine: (1) the horseshoe vortex, (2) the passage vortex, (3) endwall crossflow and the saddle point due to flow separation and (4) reattachment line on the suction wall, have been reproduced in this facility. Qualification of this facility was by comparison to a multiblade flow in the same laboratory. With the use of a side wall, a satisfactory replication of the cascade flow was found under the same flow conditions. Various flow visualization techniques were employed to confirm that the cascade flow was replicated. The oil and lampblack, single tuft probe and ink-dot-liquid-film techniques provided shear stress direction and streamline patterns on the endwall and the airfoil surfaces. A tuft grid showed the sense of rotation and the evolution of the vortex as it proceeded through the passage. The test section, now qualified, will be used to investigate the effects of various conditions which are representative of gas turbine flows and to evaluate various techniques for managing the endwall flow.
|Original language||English (US)|
|Journal||American Society of Mechanical Engineers (Paper)|
|State||Published - Dec 1 1990|