Experimental and Numerical Study of Jet Impingement Cooling for Improved Gas Turbine Blade Internal Cooling With In-Line and Staggered Nozzle Arrays

Abstract

Internal cooling of gas turbine blades is performed with the combination of impingement cooling and serpentine channels. Besides gas turbine blades, the other turbine components such as turbine guide vanes, rotor disks, and combustor wall can be cooled using jet impingement cooling. This study is focused on jet impingement cooling, in order to optimize the coolant flow, and provide the maximum amount of cooling using the minimum amount of coolant. The study compares between different nozzle configurations (In-line and staggered), two different Reynold's numbers (1500 and 2000), and different stand-off distances (Z/D) both experimentally and numerically. The stand-off distances (Z/D) considered are 3, 5, and 8 In jet impingement cooling, the jet of fluid strikes perpendicular to the target surface to be cooled with high velocity to dissipate the heat. The target surface is heated up by a DC power source. The experimental results are obtained by means of thermal image processing of the captured Infra-Red (IR) thermal images of the target surface. Computational fluid dynamics (CFD) analysis were employed to predict the complex heat transfer and flow phenomena, primarily the line-averaged and area-averaged Nusselt number and the cross-flow effects. In the current investigation, the flow is confined along with the nozzle plate and two parallel surfaces forming a bi-directional channel (bi-directional exit). The results show a comparison between heat transfer enhancement with in-line and staggered nozzle arrays. It is observed that the peaks of the line averaged Nusselt Number (Nu) become less as the stand-off distance (Z/D) increases. It is also observed that the fluctuations in the stagnation heat transfer are caused by the impingement of the primary vortices originating from the jet nozzle exit.

Heat Transfer and Crossflow Investigations for Jet Impingement Cooling Applications

“…The experimental setup is designed to study emerging passive cooling strategies for gas turbine blades leading edge, as described in previous research by Salem et al [26]. The testing apparatus contains a confined chamber with a square cross-section with an edge length of 235 mm and a height of 115 mm.…”

Experimental Investigation of the Effectiveness of Jet Impingement Cooling System on the Pressure Side of the Turbine Blade

“…The cooling system plays a key role in maintaining the turbine components temperature below critical level and in avoiding overheating failure [4]. Several internal cooling methods may be used to improve the heat transfer of turbine blades, including rib turbulators, pin fins, dimples and jet impingement cooling [3,5]. Previously, the authors have studied the use of palm oil to reduce the friction rate in the system.…”