Effects of an embedded vortex on a single film-cooling jet in a turbulent boundary layer

Abstract

Effects of embedded longitudinal vortices on heat transfer in a turbulent boundary layer film cooled from a single injection hole are discussed. Film coolant was injected at blowing ratios 0.50 to 1.50 at a freestream velocity of 10 m/s. A single longitudinal vortex was induced upstream of the film-cooling holes. Heat transfer measurements were made downstream of injection. Flow visualization tests were conducted after the injectant was contaminated with smoke. Surveys of mean velocity and mean temperature were also made in different spanwise normal planes. For all blowing ratios examined, the embedded vortices cause significant alterations to wall heat transfer and to film-cooling distributions. Measurement of mean temperature and mean velocities in spanwise planes show that injectant is pushed to the upwash side of the vortex when the injection hole is located beneath the vortex core or vortex downwash. Evidence of injection is seen only for x/d<7.4. For other injection locations with respect to the vortex core, evidence of injectant appears for x/d up to 96, and the injectant is not swept into the vortex upwash by secondary flows.