Optimization of A Swirl with Impingement Compound Cooling Unit for A Gas Turbine Blade Leading Edge

Abstract

In this article, a compound unit of swirl and impingement cooling techniques is designed to study the performance of flow and heat transfer using multi-conical nozzles in a leading-edge of a gas turbine blade. Reynolds Averaged Navier-Stokes equations and the Shear Stress Transport model are numerically solved under different nozzle Reynolds numbers and temperature ratios. Results indicated that the compound cooling unit could achieve a 99.7% increase in heat transfer enhancement by increasing the nozzle Reynolds number from 10,000 to 25,000 at a constant temperature ratio. Also, there is an 11% increase in the overall Nusselt number when the temperature ratio increases from 0.65 to 0.95 at identical nozzle Reynolds number. At 10,000 and 15,000 of nozzle Reynolds numbers, the compound cooling unit achieves 47.9% and 39.8% increases and 63.5% and 66.3% increases in the overall Nusselt number comparing with the available experimental swirl and impingement models, respectively. A correlation for the overall Nusselt number is derived as a function of nozzle Reynolds number and temperature ratio to optimize the results. The current study concluded that the extremely high zones and uniform distribution of heat transfer are perfectly achieved with regard to the characteristics of heat transfer of the compound cooling unit.

Heat Transfer Augmentation through Different Jet Impingement Techniques: A State-of-the-Art Review

“…It was observed from the results that cross-flow effects (not favorable) are minimized by either grooves or swirling jets and heat transfer is augmented for small separation distances. A numerical investigation was performed by Fawzy et al [97] in Sapra and Chander [94] experimentally studied the effect of various operating and design parameters on impingement heat transfer performance in dual swirling burning with a tangential entry. The parameters studied were Reynolds number, equivalence ratio, and separation distance.…”

“…It was observed from the results that cross-flow effects (not favorable) are minimized by either grooves or swirling jets and heat transfer is augmented for small separation distances. A numerical investigation was performed by Fawzy et al [97] in which swirl and impingement techniques for cooling turbine blades using multiple conical nozzles were combined to achieve optimal heat transfer performance. It was observed from the results that by increasing the Reynolds number value from 10,000 to 25,000, this compound cooling technique can achieve a 99.7% increase in heat transfer augmentation for a constant temperature ratio.…”