Parametric Study and Correlation of Racetrack Shaped Jets for Leading Edge Impingement

Abstract

This paper provides a detailed experimental investigation of heat transfer and pressure loss for leading edge jet impingement using square-edged, racetrack jets. Experiments were carried out over various parameters: jet-to-jet spacings (s/d) of 2, 4, 8; jet-to-target surface spacings (z/d) of 2 and 4; jet plate thicknesses (l/d) of 1.33, 2.6, and 4; and Reynolds numbers from 10,000 to 100,000. The results show that pressure loss and heat transfer decrease with increasing s/d and z/d. There is an interesting observation for jet plate thickness at l/d = 2.6—a local minima for both heat transfer and pressure loss is measured with the racetrack shaped jets. Using the exhaustive experimental data, design correlations are developed to estimate the surface Nusselt number and discharge coefficients within the domain of geometric and flow parameters. The novel correlations account for the parametric effects and can accurately predict the Nusselt number and discharge coefficient with deviations of 19.8% and 15.9%, respectively. These provide a capability for the engine designers to predict the heat transfer and pressure loss for leading edge jet impingement.