Structure improvement on turbine guided vane cooling system based on conjugate heat transfer

To improve the cooling performance of the turbine guided vane, conjugate heat transfer is utilized to investigate the internal and external cooling systems in real working conditions. The purpose is to increase the overall cooling effectiveness with limited influence on coolant consumption and cascade pressure loss factors. Firstly, the internal cooling is improved to enhance heat transfer by installing impingement cooling, ribs, dimples, and protrusions. Then, by adopting film holes near the shroud and hub, the coolant coverage of the external cooling is improved. To explain the influence of structure modification, the flow field is analyzed while the blockage effect of various structures on the crossflow is compared. The flow mechanism of conical dimples and protrusions is concluded. Results show that the improvement in internal cooling enhances heat transfer and decreases coolant consumption. However, the external film cooling deteriorates. By installing dimples and protrusions, the effusion condition of jet nozzles deteriorates. Dimples have higher heat transfer performance than protrusions. By improving external cooling, increases in film cooling effectiveness, discharge coefficients of jet nozzles, and heat transfer can be found. However, the coolant consumption increases. At Reynolds number of 15003-19599, the best-performing structure, by combining impingement/effusion cooling with ribs and protrusions, increases overall cooling effectiveness by 0.54-8.01% and 9.81-11.62% on the pressure surface and suction surface respectively. However, changes in coolant consumption (0.63-2.45%) and cascade pressure loss factors (-7.51-4.81%) are limited. The improvement thoughts and influence factors on the cooling performance are concluded, serving as guidance for the vane design.