The Numerical Study Of A Control Method Of Blowing From The Rim Of Squealer Tip In Turbine

As one of the main power device in the field of energy and power,gas turbine plays an important role in the national economy.Turbine is one of the core components of gas turbine,and its advanced degree determines the performance of gas turbine.There is a gap between the blade tip and the casing to ensure the normal operation of the turbine.The existence of tip clearance causes leakage flow and losses.Tip leakage flow has a serious negative impact on blade load,fuel consumption,heat load at blade tip and overall efficiency.Especially in recent years,turbines has been developing towards high performance,high load,low series and high power,which makes the speed of leakage flow increased and the flow field near the tip region more complex.Therefore,the research on control method of tip leakage flow is of great significance for improving the overall performance of gas turbines.The squealer tip is the most commonly tip treatment method,and the shape of the squealer tip has a great influence on the leakage flow.Tip injection is an active control method of leakage flow,injection on the flat tip can decrease leakage flow effectively,while injection on the bottom of squealer tip cannot improve leakage flow.Hence,a tip structure of blowing from the suction side rim of squealer tip is proposed in this paper,and the effect of this new tip structure on leakage flow is studied by numerical method.Firstly,a mathematical method is proposed to reshape the suction side profile of the squealer tip,and a new squealer tip variant with thicker suction side rim is obtained.Furthermore,the difference between effect of the new squealer tip and the conventional squealer tip on leakage flow are compared,and the effects of different depth of cavity on leakage flow are discussed.Beside,jet holes are arranged on the suction side,and the effects of various jet angles,blowing rate and the number of jet holes on leakage flow and heat load near the tip region are studied.It is found that the new squealer tip can effectively reduce the aerodynamic loss caused by leakage flow.Compared with flat tip,the total pressure loss of exit section decreases by about 8%.With the increase of depth of cavity,the leakage flow rate is reduced.The flow field of the leakage flow is significantly changed by air injection.Under the interaction of jets and leakage flow,wedge-shaped low-speed zones are formed downstream of jet holes.When ?=60° and ?=45°,air injection has a great blocking effect on the leakage flow.A lower leakage flow rate and a smaller loss at exit are obtained.At the same time,it brings well cooling coverage on the surface of suction side rim.With the increase of blowing rate,the flow rate of leakage from the pressure side decreases gradually,and the interaction between the jets and the leakage flow raise,thus reducing the size of tip leakage vortex at exit section.When the blowing rate is 1.5,the better cooling coverage and a great film cooling efficiency are obtained.When the number of jet holes is 7,a better aerodynamic and thermodynamic performance can be obtained.