Jet impingement heat transfer on a concave surface in a wing leading edge: Experimental study and correlation development

Extensive experimental studies of the heat transfer characteristics of jet impingement on a variable-curvature concave surface in a wing leading edge were conducted for aircraft anti-icing applications. The experiments were performed using a piccolo tube with three rows of aligned jet holes over a wide range of parameters: the jet Reynolds number (Rej) from 50,000 to 90,000, the relative tube-to-surface distance (H/d) from 1.74 to 20.0, the jet impingement angle (α) from 66° to 90°, and the relative chordwise arc length in the jet impingement zone (r/d) from 13.2 to 34.8. Experimental results indicated that the heat transfer performance at the stagnation point was enhanced with increasing Rej and α, and an optimal H/d existed to achieve the best heat transfer performance at the stagnation point corresponding to specific operating parameters. It was found that the attenuation coefficient curve of jet impingement heat transfer in the chordwise direction exhibited an approximate bell shape with the peak located at the stagnation point, affected only by r/d in the peak zone. In the non-peak zone, however it was affected significantly by a variety of factors including Rej, H/d and r/d. Experimental data-based correlations of the Nusselt number at the stagnation point and the distribution of the attenuation coefficient in the chordwise direction were developed and validated, which contributes significantly to the future design of a wing anti-icing system with three rows of aligned jet holes.