Investigations of flow and film cooling on turbine blade edge regions

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Title: Investigations of flow and film cooling on turbine blade edge regions
Author: Yang, Huitao
Abstract: The inlet temperature of modern gas turbine engines has been increased to achieve higher thermal efficiency and increased output . The blade edge regions , including the blade tip , the leading edge , and the platform , are exposed to the most extreme heat loads , and therefore , must be adequately cooled to maintain safety . For the blade tip , there is tip leakage flow due to the pressure gradient across the tip . This leakage flow not only reduces the blade aerodynamic performance , but also yields a high heat load due to the thin boundary layer and high speed . Various tip configurations , such as plane tip , double side squealer tip , and single suction side squealer tip , have been studied to find which one is the best configuration to reduce the tip leakage flow and the heat load . In addition to the flow and heat transfer on the blade tip , film cooling with various arrangements , including camber line , upstream , and two row configurations , have been studied . Besides these cases of low inlet /outlet pressure ratio , low temperature , non -rotating , the high inlet /outlet pressure ratio , high temperature , and rotating cases have been investigated , since they are closer to real turbine working conditions . The leading edge of the rotor blade experiences high heat transfer because of the stagnation flow . Film cooling on the rotor leading edge in a 1 -1 /2 turbine stage has been numerically studied for the design and off -design conditions . Simulations find that the increasing rotating speed shifts the stagnation line from the pressure side , to the leading edge and the suction side , while film cooling protection moves in the reverse direction with decreasing cooling effectiveness . Film cooling brings a high unsteady intensity of the heat transfer coefficient , especially on the suction side . The unsteady intensity of film cooling effectiveness is higher than that of the heat transfer coefficient . The film cooling on the rotor platform has gained significant attention due to the usage of low -aspect ratio and low -solidity turbine designs . Film cooling and its heat transfer are strongly influenced by the secondary flow of the end -wall and the stator -rotor interaction . Numerical predictions have been performed for the film cooling on the rotating platform of a whole turbine stage . The design conditions yield a high cooling effectiveness and decrease the cooling effectiveness unsteady intensity , while the high rpm condition dramatically reduces the film cooling effectiveness . High purge flow rates provide a better cooling protection . In addition , the impact of the turbine work process on film cooling effectiveness and heat transfer coefficient has been investigated . The overall cooling effectiveness shows a higher value than the adiabatic effectiveness does .
URI: http : / /hdl .handle .net /1969 .1 /4338
Date: 2006-10-30

Citation

Investigations of flow and film cooling on turbine blade edge regions. Available electronically from http : / /hdl .handle .net /1969 .1 /4338 .

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