Film cooling effectiveness for short film cooling holes fed by a narrow plenum

The adiabatic, steady-state liquid crystal technique was used to measure su rface adiabatic film cooling effectiveness values in the near-hole region ( X/D<10). A parametric study was conducted for a single row of short holes ( L/D <less than or equal to> 3) fed by a narrow plenum (H/D = 1). Film cooli ng effectiveness values are presented and compared Sor various L/D ratios ( 0.66 to 3.0), three different blowing ratios (0.5, 1.0, and 1.5), two diffe rent plenum Seed configurations (co-flow and counterflow), and two differen t injection angles (35 and 90 deg). Injection hole geometry, and plenum fee d direction were found to affect short hole film cooling performance signif icantly. Under certain conditions, similar or improved coverage was achieve d with 90 deg holes compared with 35 deg holes. This result has important i mplications for manufacturing of thin-walled film-cooled blades or vanes. [ S0889-504X(00)00603-6].