Numerical Analysis of Jet Impingement Cooling Using Converging Conical Hole for Blade Leading Edge

The objective of this present work is to investigate numerically the effect of converging conical hole on blade cooling at leading edge. Diameter ratio of the converging conical holes is maintained as two with a converging angle of 20°. Cylindrical geometry used by Lee et al. [5] for the experimental investigation is taken as base reference for this present numerical investigation. Turbulence model study is carried out with three different models and kω-SST is found to give closer result with the experimental data. Subsequent investigations are carried out using kω-SST turbulence model. The target surface for the present study is 19.05 cm in radius and the diameter of the impingement hole is 1.30 cm, 2.15 cm 3.40 cm. The jet hole to the target surface spacing is varied as R/4, R/2 and 3R/4. The steady-state Reynolds Averaged Navier Stokes equations are solved for different impingement hole diameters at Reynolds number of 11000, 23000 and 50000. The target surface is maintained at constant heat flux of 10000 W/m². Numerically computed Nusselt number and temperature distribution for the convergent conical hole and cylindrical hole are compared. Around 186% increase in Nu and 13% decrease in surface temperature is observed at the stagnation point for the optimum case in this present study i.e, jet spacing R/2, converging conical hole diameter 2.15 cm and Re 23000. The converging conical hole configuration increases the fluid velocity in the potential core region and enhances the heat transfer. It is followed by 185% increase in Nu and 15.58% reduction in target surface temperature for Re 11000 and 170% increase in Nu and 7.28% reduction in temperature for Re 50000.