Research On Fluid Flow And Heat Transfer In Turbine Rotor Blade With Complex Internal Cooling

Su Sheng (Engineering Thermophysics)Supervised by Professor Liu Jian-JunThe application of effective cooling technology can allow turbine blade to undergohigh gas temperature and can increase the blade security and durability,and also the gasturbine efficiency.In this dissertation,the fluid flow and heat transfer in typical internalcooling configurations of a gas turbine rotor blade,including rib-roughened duct orserpentine passage,and matrix cooling,were studied.Both numerical simulations andexperiments based on transient heat transfer technology with thermochromic liquid crystalwere carried out.The numerical method used for the simulations was validated byexperimental results.Conjugate heat transfer method was used to study the fluid flow andheat transfer in the turbine rotor blade.In the rib-roughened duct,ribs induce secondary flow and break up the flow boundarylayer,result in enhanced heat transfer on the ribbed walls.When a smaller rib is planted ina proper location between each two original ribs,better heat transfer can be obtained andthe fluid flow resistance may also be decreased.Both numerical and experimental resultsshow that the integrated heat transfer ability,considering both the heat transferenhancement and the pressure loss,can be improved.The heat transfer and fluid flow in a rotating unsymmetrical two-pass serpentinepassage were numerically studied.Compared to the results in smooth serpentine passageand stationary rib-roughened serpentine passage,ribs planted only on one wall as in theinlet passage play a dominant role on the fluid flow and heat transfer.The effects ofCoriolis force come out gradually in the outlet passage.Coriolis force changes the vortexshape in the outlet passage,even changes the vortex configuration in some places.Rotatingenhances the heat transfer on both the front edge and back edge in the outlet passage.Due to the effect of Coriolis force,the enhancement of heat transfer on the back edge is higherthan that on the front edge.Three geometrical parameters have significant impacts on fluid flow and heat transferin matrix cooling.The parameters are rib width to height ratio b/h,rib width to pitch ratiob/p and the rib incline angleβ.The numerical and experimental results of seven differentmodels show that smaller b/h,or bigger b/p or biggerβleads to higher flow resistance.However,the heat transfer ability on the rib-roughened walls does not increase or decreasein a monotone way.The fluid flow and heat transfer studies for the turbine rotor blade were carried out bychanging the rib scale of matrix cooling,including or excluding tip film cooling,tip innerclearance and tip clearance.Numerical results obtained by using conjugate heat transfermethod show that each configuration has its own characteristics and interactions amongconfigurations are also found.Internal cooling has some effects on the flow angle and totaltemperature distribution at blade outlet,however,has small effect on blade aerodynamicload.Smaller scale of rib width and pitch leads to more unique temperature distributions inthe corresponding blade area.When tip clearance is considered,cooling air ejected fromthe tip holes can cool the leading edge and middle part of the blade tip.Inner clearancenear the blade tip can improve the fluid flow in the matrix sub-channels lying on the bladesuction side,consequently the suction side can be better cooled.In addition,cooling airflowing through the inner clearance near the blade tip can cool the trailing edge at the tipnecessarily and effectively.