Improvement Of Film Cooling Structure Of Gas Turbine Rotor Blades And Numerical Simulation Of Cooling Effect

Increasing the turbine inlet temperature is an important way to improve gas turbine performance and its economics.Due to the thermal resistance of the blade material,the effective cooling measures such as internal cooling and film cooling must be taken to protect the turbine blade.However,the gas jet ejected from a cylindrical hole of the conventional cooling structural is easy to entrainment and mix with the mainstream,which is not conducive to improving the overall cooling effect.Improving the conventional film cooling structure and optimizing its cooling characteristics will effectively improve the cooling efficiency of the gas turbine rotor blades.Therefore,an improved structure for the turbine rotor blade film cooling was proposed and the numerical simulation study on the film cooling effect of the improved structure were carried out in this dissertation,which could provide theoretical guidance for the design of rotor blade film cooling structure in engineering practice.The major research work has been completed as follow:Firstly,an improved gas film cooling structure with convergent-divergent shaped film cooling holes was proposed,and the film cooling characteristics of which were compared with the characteristics of conventional cooling structural with cylindrical holes.The results show that the film cooling effect of the convergent-divergent shaped holes is better than that of the cylindrical holes whether it is on the pressure surface or the suction surface of the blade.and the gas film flows towards the deflection angle of the blade and the whole film on the blade surface exhibits a deflection and superposition phenomenon.Then,the effects of the expansion angle and the hole spacing of the convergent-divergent shaped holes on the air film cooling efficiency of the rotor blade were analyzed in detail.The key findings summarized as follows:(i)When the expansion angle increases from ?=0° to?=10°,the air film cooling efficiency increases on the blade.The cooling non-uniformity coefficient decrease and the air film cooling effect is enhanced.When the expansion angle increases from ?=10° to ?=15°,the cooling non-uniformity coefficient increases and the cooling effect is weakened.(ii)With the decrease of the hole spacing,the interaction between the holes is strengthened.The average air film cooling efficiency increased with the decrease of the hole spacing,which can get a improved cooling performance.Finally,the effects of blowing ratio on the air film cooling effect of different convergent-divergent shaped holes are analyzed in detail.The study results show that blowing ratio has a great influence on the air film cooling efficiency.As the blowing ratio increases,the film cooling effect is first strengthened and then weakened when the expansion angle is ?=0°,but in the same case the film cooling effect tends to increase when the expansion angle is ?=5° and ?=10°.