A Computational Study Of Flow And Heat Transfer In Jet Impingement-Effusion Cooling System For Gas Turbine Components

This work centers on the combination of two efficacious and practical cooling schemes for gas turbine components,i.e.Impingement cooling and effusion cooling,coalesced together as an Impingement-effusion cooling scheme that integrates the advantages of both the cooling technologies.Sophisticated aviation and power generation industries heavily bank on ameliorated and efficient performance of gas turbine engines,which can be improved by the technical furtherance of gas turbine cooling systems-as turbine engines work on Brayton thermodynamic cycle and elevated turbine inlet temperatures will result in higher efficiency,but increasing inlet temperature has been constrained by the melting point of the combustor and turbine blade materials.In order to cope with the ever-increasing demand of the turbine inlet temperature,it is imperative that a very efficacious cooling methodology-along with the advancement and improved understanding of material sciences-is needed for better efficiency and better protection of the life of gas turbine engine components,hence the multi-modal significance of the present work as it contributes to continuous research and development of the newfangled cooling scheme and also analyzes the material used.The parameters effecting overall film effectiveness for effusion cooling and Nusselt number distribution for impingement jets are the focal points of this work.Although impingement cooling is a part of this study,more attention has been paid to effusion cooling and cooling enactment on the external wall.Mainstream software packages for Computational Fluid Dynamics were used to simulate gas turbine combustor and blade walls.Hole arrangement has also been varied and analyzed,four different arrangements namely Straight holes,a staggered arrangement,hexagonal arrangement and a completely new and unique Alternative arrangement have been explored.Three different materials have been used for target plate-Copper,Nimonic-263 and Ceramic Matrix Composite for the analysis of overall film effectiveness on the exposed surface.For the validity of CFD results,comparison with the experimental results has been made.Computational model results for flow-only domain show a good agreement with experimental results as the highest deviation being less than 10 percent.Flow-only region and conjugate heat transfer-the interaction of heat conduction in solid and heat convection from its surface,both have been studied and compared,weighing of conjugate heat transfer scenario against flow-only domain diversifies this work as compared with mainstream literature domains.For film effectiveness,hexagonal arrangement yields as high as 24.68% and 18.18% improvement for CMC and Nickel super alloy plates respectively.For Nusselt number distribution,Alternate holes arrangement has a superior result to all the other shapes with CMC material having the highest averaged Nusselt number distribution.The overall film effectiveness,in contrast with a Nusselt number,is found to be highly sensitive to the hole arrangement,angle of inclination,blowing ratio and thermal conductivity of the target plate material.