Investigation On Effect Of Hole Shapes On Film Cooling In A Flat Plate For Gas Turbine Applications

Gas turbine is largely used in many fields such as aeroengine, watercraft,electricity, metallurgy, chemical industry, energy and power engineering. The heatefficiency of gas turbine increases when enhancing the inlet temperature, though thethermostability behavior of blade is limited. So it is necessary to cool and protect theblade. Film cooling is more important as one cooling technology of gas turbine blade.It is not complicated to study each parameter of film cooling in a flat plate, and theresult of flat plate can be used in design of actual engineer after little rectification.The effect of film cooling depends on the flow quality of nearby cooling holes and ismeasured with the effectiveness of film cooling.Numerical computation basing on the software FLUENT, using RNG k-εturbulent model，finite control volume method, SIMPLEC algorithm and segregatedimplicit steady solver to solve the Navier-Stokes equations, under different blowingrations and rows pattern this paper studied the effectiveness, vortex structure of theflow field and flow structure of holes’ interior of four kinds of holes.The results of this study mainly include the following parts:(1)under selectedfour blowing ratios, the area covered by cooling film of lateral expanded hole andnovel antivortex hole is more larger and the efficiency of hole centerline is bettercompared to diffused and cylindrical holes, the film cooling efficiency of ambientholes of antivortex hole is best; the effectiveness on centerline of four holes is verynearly the same when blowing ration is0.5;(2) The effectiveness of cylindrical holedecreases when increasing the blowing ratio, but the other holes are reverse;(3) Atthe same blowing ratio, the scale of reverse vortex pair of cylindrical hole is largerthan the other holes. Diffused and lateral holes restrain the reverse vortex pair atdifferent levels. With extending downstream, the vortex’s center is gradually far awayfrom the wall surface. The side holes of novel antivortex hole also restrains thereverse vortex pair;(4) Holes’ structures affect the flow structure of hole’s interior. Because the cross section of the cylindrical hole is constant, it doesn’t generate flowseparation easily in hole’s internal and the area of low velocity is larger than diffusedand lateral holes. The cross sections of diffused holes and lateral expanded holes isgradually diffused, so their flow velocities in holes slow down and the area at low andhigh velocity is obvious;(5) The influence of two inline rows of holes on coolingeffect of downstream is slightly. But film cooling effectiveness between holes isobviously increased when staggered configuration.