| With the further improvement of power and efficiency requirements of modern advanced gas turbines,the thermal environment of gas turbine components becomes worse.Therefore,high-performance cooling technology is urgently needed.External cooling(convection cooling,gas film cooling,sweating cooling),as an important cooling method for gas turbine high-temperature components,is widely used on turbine blade surface because of its good cooling performance.Sweat cooling for future advanced gas turbine adopt more effective active thermal cooling way,combining the advantages of the gas film cooling way,using the porous medium material properties,uniform dispersion cooling fluid flow,the larger specific surface area and porous media internal volume to provide sufficient space for heat exchange,to achieve large area and reusable thermal protection,And the cooling structure and the bearing structure of the heat bearing part can be separated to bear a certain force impact.In this paper,perspiration cooling was taken as the main research object.Experimental data were used to verify the accuracy of the local thermal nonequilibrium model.Under the local thermal nonequilibrium model,heat transfer properties of confined laminar impingement jet flow in porous media were studied,and Realizable k-ε turbulence model was used to study the cooling efficiency of simplified plate perspiration cooling.The cooling efficiency of air-cooled turbine blade surface with sweat cooling was studied under the K-ω-SST turbulence model.Firstly,the accuracy of the local thermal nonequilibrium model to simulate the flow and heat transfer in the porous media was investigated for the impact of the confined plate impingement jet on the porous media plate.The effects of changing the inlet Re number,Da number,porosity of the porous media material and the thickness of the porous media plate on the convective heat transfer were analyzed.The simulation results show that the local thermal non-equilibrium model is more accurate than the local heat balance model in the simulation of flat impingement jet in the impingement stagnation area.Packing porous media can effectively improve the flow structure in the channel,and increasing the Re and Da numbers at the entrance is more conducive to the stagnation of regional flow heat transfer,while the porosity has no obvious effect on the flow heat transfer in the channel.Finally,based on the research results of plate sweating cooling,a local thermal nonequilibrium model was used to simulate the sweating cooling heat transfer situation of Ge-E3 turbine blade surface with tile porous media,and the comparison was made with the heat transfer situation of air film cooling.The simulation results show that the turbine blades cooled by sweat can restrain the coolant lift more effectively than the air-cooled turbine blades.The coolant extends on both sides of the pores and downstream,which increases the area of the cooling air film and strengthens the cooling effect.When the blowing ratio is changed,the perspiration cooling increases with the blowing ratio increasing,and the film cooling increases first and then decreases with the blowing ratio increasing.Under the same blowing ratio,the cooling efficiency and cooling area of sweat cooling are larger than that of air film cooling.The decrease of porosity can improve the cooling effect of turbine blades. |
