LEADING-EDGE FILM-COOLING EFFECTS ON TURBINE BLADE HEAT-TRANSFER

A three-dimensional Navier-Stokes code has been used to study the effe ct of spanwise pitch of shower-head holes and coolant to mainstream ma ss flow ratio on the adiabatic effectiveness and heat transfer coeffic ient on a film-cooled turbine vane. The mainstream is akin to that und er real engine conditions with stagnation temperature 1900 K and stagn ation pressure 3 MPa. It if found that with the ratio of coolant to ma instream mass flow being fixed, reducing the spanwise pitch for shower -head holes (P) from 7.5d to 3.0d, where d is the hole diameter, incre ases the average effectiveness considerably over the blade surface. Ho wever, when P/d = 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces a oil the suction su rface owing to coolant jet lift-off For P/d = 4.5 or 3.0 such an anoma ly does not occur within the range of coolant-to-mainstream-mass-flow ratios analyzed. In all cases, adiabatic effectiveness and heat transf er coefficient are highly three-dimensional.