Investigation On Flow And Heat Transfer Of Turbine Blade In Cascade Passage

As combustion chamber outlet temperature increasing year by year, the working environment ofturbine blades is becoming more and more severe, and the heat resistance of that material can’t satisfythe inlet raising temperature of turbine. At the same time, along with the growing of pressure ratio, thetemperature of the cooling air from compressor is rising, while the potential of cooling air becomessmaller. Therefore, only by optimizing the existing cooling way ceaselessly and excavating newcooling methods, can the aero engine thrust-weight ratio be improved. Thus we can as well ensureengine working reliability and enhance its service life.The object of research is based on cooling blade. Combining with experiment and numericalsimulation, the external flow properties of blade is studied in two opposite conditions, one with filmcooling and one without. The main content of the study is passage vortex variation and the interactionbetween passage vortexes and counter-rotating vortex pair under different blowing ratios in thecascade passage. The results show that along with the direction of mainstream, passage vortexesbecame closer to the central and the suction surface of blade continuously. With the increasing ofReynolds number, the cascade loss coefficient presents growth trend. One of counter-rotating vortexpair which is close to the end wall is enhanced by passage vortex. At the same time, following withthe increase of blowing ratio, the effect of counter-rotating vortex pair on passage vortex is enhancing.The results of the heat transfer research show that, the heat transfer of leading edge is the best,and the heat transfer of suction surface is stronger than pressure surface. Because of the influence ofpassage vortexes, the heat transfer is enhanced in the end wall of suction surface. The cooling air isinjected to mainstream to varying degrees in the suction surface in the condition with film holes, sowith the increasing of blowing ratio, the cooling efficiency of the front half part decreases and thecooling efficiency of the latter half part rises. For mainstream oppression to the cooling air, thecooling air can be attached to the surface of the blade well in the pressure surface. Therefore thecooling efficiency of the whole pressure surface rises as well as the increase of blow ratio. Thecooling air jet close to the end wall formed the low temperature zone along with the mainstreamvertical section, and the shape of it has a little deformation for the reason of the passage vortex effect.The shape of low temperature area away from the end wall, appear on more rules and in asymmetrical distribution. Downstream along the flow direction, the temperature of low temperaturearea rising.The object of the forth chapter is a composite cooling structure, which is calculated using fluent software, and then the advantages and unreasonable part are analyzed. Following with the optimizedstructure is calculated, the calculation results of the previous structure and the optimized structure arecompared. The temperature of leading edge decreases, the temperature distribution of the whole bladetends to more uniform.