Study On Flow And Heat Transfer Characteristic Around A Rib By Using An Obstacle In The Upstream Region

The design of the internal cooling channel inside the turbine blade is of great significance for improving the inlet temperature of the turbine and further improving the engine efficiency.In this paper,the internal cooling channel is taken as the research object.By means of numerical simulation and experimental method,the flow and heat transfer characteristics of the cooling channel are analyzed,in order to provide reference data for further optimization design.Firstly,the high-accuracy turbulence model——Very Large Eddy Simulation(VLES)was introduced and verified.Then the flow and heat transfer characteristics of typical ribbed channel are analyzed.On the basis of those,a new kind of cooling unit——a rib with an obstacle upstream is carried out.The flow and heat transfer characteristics under typical operating conditions are analyzed numerically.The effects of inlet Reynolds number(Re =38,000 ~ 54,000)and the geometric parameters of the obstacle,including the height(H/e = 1 to 4,e is the height of the rib),the width(w/e = 1 to 4),the length(l/e = 1 to 4)as wall as the distence between the obstable and the rib(s/e = 1 ~ 4)are discussed by means of sensitivity analys is.The results show that the presence of upstream obstacle makes the heat transfer coefficient of the area between the obstacle and the rib greatly increase.The heat transfer coefficience of the channel surface increases with a larger inlet Re number and a higher obstacle.The most influential factors are the height and length of the obstacle.Among the calculation conditions of this paper,when the height of obstacle is 2e and the length is 4e,a largest coefficient of comprehensive performance can be obtained.Finally,the new cooling unit is studied exper imentally by using the Transient Liquid Crystal(TLC)technology.The influentce of the inlet Reynolds number(Re =38,000 ~ 54,000)and the obstacle height(H/e=1 ~ 4)to Nu number are researched.It is found that as the inlet Reynolds number increases,the heat transfer coefficience on the surface increases gradually.The heat transfer coefficience increases with the increasing of obstacle height.