Investigation On Flow And Heat Transfer Characteristics Of Trapezoidal Channel In Gas Turbine Blade

Rib-turbulated cooling is one of the main cooling methods for the gas turbine blade internal cooling.Early studies focused mainly on the ribbed cooling channels that the cross-section of which is square and rectangular.However,the cross-sections of internal cooling passages in real gas turbine blade are not entirely square or rectangular,and in some extend,the internal cooling passages of gas turbine blade should be modeled as trapezoidal ribbed channels.Therefore,it is necessary to carry on detailed experimental and numerical simulation study on the cooling structure of the trapezoidal ribbed channel of gas turbine blade.In this study,the flow and heat transfer characteristics of air in the trapezoidal and rectangular cooling channels are compared and analyzed by experimental and numerical simulations.Then,the effects of the Reynolds number,rib angle,rib height and rib pitch on the flow and heat transfer performance of the trapezoidal cooling channels are studied to obtain the optimal cooling structures of gas turbine blade internal cooling passages.The study found that the two trapezoidal channel with ribs on the wall surface of the heat transfer coefficient increases with the increase of Reynolds number and Reynolds number;in the study,90 degrees trapezoidal ribbed channel narrow surface heat transfer coefficient is slightly higher than the width of surface heat transfer coefficient corresponding;Reynolds number increases from 6000 to 30000 trapezoidal channel,wide and narrow face of the heat transfer coefficient was increased by 2.6 times and 3 times,the comprehensive thermodynamic coefficient were decreased by 59%and 56%,the channel friction factor increases by 18.1 times.The thermal coefficient of trapezoidal channel is about 2.1%higher than that of rectangular channel.The heat transfer coefficient and the thermal coefficient of the 45 degree trapezoidal rib channel with wide and narrow faces are the highest,and the pressure loss of the channel with the 60 DEG ribs is the largest.After calculation,30 degrees,45 degrees,60 degrees and 90 degrees trapezoidal ribbed channel is narrow the comprehensive thermodynamic coefficient respectively than the width of higher than 1.9%,2.1%,3.9%and 3.7%;45 degrees trapezoidal ribbed channel wide and narrow surface heat transfer coefficient is 90 degrees trapezoidal ribbed channel were increased by 46.1%and 53.3%,while the thermal stress coefficient were increased by 31.3%and 35.6%.The trapezoidal ribbed channel wide and narrow face of the heat transfer coefficient and thermal coefficient with the increase of the fin height increases first and then decreases,the fin height is 7.2mm trapezoidal ribbed wall surface heat transfer coefficient and the thermal coefficient is the highest;the fin height is 12mm trapezoidal rib pressure loss reaches the maximum value.The trapezoidal ribbed channel is wide and the narrow face number and thermal coefficient with increase of the spacing between adjacent fins decreases,P/e 5 trapezoidal ribbed channel wall average Nusselt number and thermal coefficient is the highest;the trapezoidal ribbed channel pressure loss increases with the spacing between adjacent fins first increase and then decrease,the rib spacing and the rib height ratio of 15 channel pressure loss reaches the maximum value.After calculation,the spacing between adjacent fins is 5 trapezoidal ribbed channel wide and narrow the average Nusselt number than the spacing between adjacent fins is 20 respectively by 39.6%and 23.9%,and the thermal coefficient is higher than 46.6%and 29.6%respectively.In the design of internal cooling channels in gas turbine blade,it is recommended that the 60°,lower rib height(e=2.4mm)and smaller pitch(P/e=5)ribr turbulators should be arranged in the trapezoidal cooling channel of the turbine blade when the aerodynamics of ribbed channel is the main performance considered.Contrarily,the 45°,medium rib height(e=7.2mm)and smaller pitch(P/e=5)ribr turbulators are recommended to arrange in the trapezoidal cooling channel of the turbine blade if the heat transfer performance the integrated thermal performance are mainly considered.