STREAKLINE FLOW VISUALIZATION OF DISCRETE-HOLE FILM COOLING WITH NORMAL, SLANTED, AND COMPOUND ANGLE INJECTION

摘要

Film injection from discrete holes in a three-row, staggered array with five-diameter spacing was studied for three hole angles: (1) normal, (2) slanted 30° to the surface in the direction of the main stream, and (3) slanted 30° to the surface and 45° laterally to the main stream. The ratio of the boundary layer thickness-to-hole diameter and Reynolds number were typical of gas-turbine film-cooling applications. Detailed streaklines showing the turbulent motion of the injected air were obtained by photographing very small neutrally buoyant, helium-filled "soap" bubbles which follow the flow field.