PIV Experiment And Numerical Simulation Research On Turbine Blade Oblique Rib Cooling Channel

The ribbed channel is a typical form of the internal cooling structure in turbine blades,which can increase the turbulence inside the channel,play the role of forced convection heat exchange,and is of great significance for increasing the temperature in front of the turbine.Common rib structures such as straight ribs,oblique ribs,V-shaped ribs,W-shaped ribs,discontinuous ribs,concave-convex structures...,as the temperature requirements in front of the turbine continue to increase,the design of spoiler ribs is also becoming more and more complicated.Therefore,only by mastering the flow and heat transfer mechanism of the ribbed channel can the design parameters of the rib be effectively improved.In this paper,the detailed flow data obtained from the experiment and the heat transfer data from the simulation are combined to analyze the flow and heat transfer effect caused by the oblique ribs,which provides a reference for the design of the internal cooling structure of turbine blade.The core work of this paper is to use the particle imaging velocimetry(PIV)experiment method to investigate the flow characteristics of the typical cross-sections of the four schemes α=90°,80°,70°,and 60°.The experimental results show that:from the time average point of view,the range of low-speed region behind the ribs can be significantly reduced,and the intensity and range of intercostal vortices will also be significantly increased;from the transient point of view,the generation frequency of vortices gradually increases with the decrease of α,therefore,with the increase of vortex generation frequency,the turbulence intensity between ribs also increases.The results of intrinsic orthogonal decomposition(POD)show that the energy fluctuation frequency of pod coefficient increases with the decrease of α,and the energy events between ribs are more concentrated,and the intensity increases gradually.The numerical simulation part serves as the supplement and verification of the experimental part.From the calculation of the single-rib channel,the most important events of heat transfer behind the rib are learned.From the calculation of the multi-rib channel,the flow characteristics of the typical cross-sections and three-dimensional flow information of the four schemes are investigated.The flow field conditions of the four schemes were investigated more completely,and the heat transfer effect of each scheme was judged according to the evaluation system of comprehensive heat transfer coefficient.The research results show that the heat transfer behind the ribs at α=90° is mainly contributed by fluid reattachment.When α=60°,the vortex behind the ribs is closer to the wall,and the strength and instantaneous frequency of the vortex are higher,thus,the main contribution of heat transfer behind the ribs comes from the vortex.In the multi-rib channel,due to the small P/e,the reattachment advantage of the straight rib scheme disappears,while the oblique rib scheme can provide high-strength vortex,so that the oblique rib has a greater advantage in heat exchange.The smaller the α,the heat transfer intensity of the wall is higher,but higher heat transfer also brings higher pressure loss.On the whole,the comprehensive heat transfer efficiency η of the three oblique rib schemes is 1.4%、12.9%、28.7%higher than that of the straight rib scheme.