Investigation Of Influence Of Film Cooling Hole Parameters On Turbine Performance

As a impeller machinery of core machine, Gas turbine is used widely in aviationengine, heavy duty gas turbine and Marine gas turbine, etc., which is of greatimportance for the national economic construction and national territorial airspaceprotection. In the current demand of high thrust and thermal efficiency of the turbine,according to the gas turbine thermal cycle, the gas temperature before the turbine needsto be improved, also the turbine parts face the problem of high temperature and highpressure. Film cooling, as the representative of the advanced cooling technology hasbeen widely used in the design of the turbine to ensure the service life and reliability ofthe high temperature parts of turbine components. In today’s high-performance turbineengine, inlet temperature has reached more than2200K, the cold air used in filmcooling also has reached more than20%of the mainstream, which produces a greatimpact on the pneumatic and the heat transfer performance on passage of threedimensional flow field. In this paper, the main work is the study of the high-pressureturbine blade film cooling hole parameters of the aircraft engine, and analysis of theinfluence degree of different parameters on the aerodynamic performance and the heattransfer characteristics.In this paper, the research is focused on the effect of turbine blade film cooling onthe properties of pneumatic heat transfer, mainly divided into two parts: film coolingnumerical research of turbine blade’s static blades and film cooling numerical researchof turbine blade’s dynamic blades. This paper has studied the influence of themainstream respectively from cold air hole space, air conditioning, cold air incidentangle and air conditioning aperture angle, analyzed the distribution and evolution ofaspects of vorticity in the flow passage under different conditions, and the interaction ofthe oval vortex and passage vortex, finally summarizes the factors influence on theperformance of the turbine.The research in this paper takes the method of parametric modeling, one is toreduce the workload of grid generation, the other is to keep the consistency of the griddensity. First, numerical simulation of turbulence model are analyzed and compared, thetransition of the SST turbulence model numerical simulation matches well with theexperiment, So the turbulence model is used to simulate the entity later. And the independence of the grid are discussed in this paper, in order to ensure the accuracy andreliability of the calculation results.Through the analysis of the numerical simulation results of static blades, we cometo the conclusion that the cooling hole space position has a great influence on themaximum temperature on the surface of the blade. When stationary point is on thepressure side, cold air hole arrangement in the lateral position of the1.5D partialpressure, not only the highest temperature drop, the total cooling effect of the leaf isalso the highest, however, aerodynamic efficiency of the cascade drops to thecomparatively lowest, which indicates that front cooling position inevitably reducesaerodynamic efficiency while increasing the cooling effect, the cooling effect of frontposition and pneumatic performance could not achieve both. The change of airconditioning mainstream momentum ratio makes the blade surface temperature changegreatly, cold front volume increase, cascade aerodynamic efficiency reduce, the localcooling effect fall, but the overall cooling effectiveness ascend. The rate of increment ofcascade flow is only take25percents of air conditioning increment, which shows thatmost cold air accumulates in the back of the suction side, blocking the throat area,reducing the rate of flow. The decrease of the incidence Angle leads to the reduction offront local temperature, when the location of the incident angle is right₁.5D, thecooling effect could be the best. In the ocal area in front, the14shroud90₁5hub90leaves have the lowest average surface temperature, the cooling effect of airconditioning is more obvious in the tip of the blade than that in the root.In the end, we compare and analyse the numerical simulation of the moving blade,and discuss the influence of the influence factors which affect the performance of theturbine. Results show that the moving blade leading edge cold air hole is more sensitiveto spatial location, due to that the distortion of the moving blade is more noticeable,cold air space position changes make the leading edge of local temperature periodicallyfluctuate, therefore the space position of upper and lower cold air hole should distributesectionally, to ensure that the cold air could achieve good cooling efficiency. With theincrease of frontal air conditioning mainstream momentum ratio, cascade aerodynamicefficiency is improved, the increase of outlet flow is greater than the increase of thecooling air, which indicate that that the effect of momentum ratio on the mainstream isobvious. But again, the higher momentum ratio on blade surface has no effect on thehighest temperature, the local temperature of front also increases with the increase of momentum ratio, which explains that if momentum ratio is too big, air conditioningcannot effectively covering on the surface of blade. On the back area of the suctionsurface, the radial angle of the cooling air aperture has little affect on aerodynamicefficiency and cooling effect, the bigger the radial angle of the cooling air aperture inthe top part, the greater the cooling effect of the cold air; The smaller the radial angle ofthe cooling air aperture in the root part, the better the cooling effect after the cooling airhole. At the back of suction surface passage vortex, the aerodynamic efficiency of theadditional cold air hole only become slightly lower at the blade tip, the interaction ofpassage vortex and cold air hole became the main reason for the aerodynamic efficiencydecrease, but the decrease value of blade root parts’ temperature is greater than that onthe blade tip.