A Numerical Investigation Of Cooling Performance Improvement By Kagome Lattice In The Trailing Edge Of A Turbine Blade

With the increasement of the thrust-weight ratio and thermal efficiency of aero-engines,the gas temperature at the inlet of the turbine is much higher than the allowable metal temperature of the parent material of the turbine blades.To improve the cooling performance and reinforce the mechanical strength of the trailing edge with narrow space and high thermal load,this paper proposes that the Kagome metallic lattice with the properties of light weight,load bearing and heat dissipation is integrated into the trailing edge of the blade for the analysis of fluidic and thermal characteristics.First,this study presents a systematic comparison of thermo-fluidic behaviors between two sandwich panels with single-layered Kagome and wire-woven bulk Kagome(WBK)cores under identical Reynolds number and porosity.The results reveal that the Kagome sandwich panel exhibits about 30% higher overall Nusselt number relative to the WBK sandwich panel for a given pumping power,though the area-averaged Nusselt number on the ligaments of the Kagome panel is about 42%lower than that of the WBK panel.This is attributed to more high momentum vortices and higher turbulent kinetic energy near the endwall in the Kagome panel compared to the WBK panel.Stronger vortex flow close to heated endwalls improves the endwalls heat transfer behavior and the overall thermal performance.Second,this study introduces Kagome lattice to replace the pin-fins or ribs in the wedge-shaped channel.According to the fluidic characteristics of the wedge-shaped channel,three models with three kinds of arrangements of turbulators are put forwards and compared with the performance of pin fin and ribs.The underlying thermo-fluidic mechanisms of the four designed channels are investigated numerically under the stationary condition.The results reveal that the model(Model 4)with three arrays of Kagome cores and ribs exhibits about 22% and 33.7% higher overall Nusselt number relative to the model with two arrays of Kagome lattices and ribs(Model 2),and the model with three arrays of pin fins and ribs(Model 3).While the model with two arrays of pin fins and ribs provides similar thermal perfrmance to the Model 2.This is attributed to the fact that the first array of Kagome cores of Model 4 separate more high momentum fluids to the tip region,resulting in the reduction of the recirculation flows and the promotion of convective heat transfer.Finally,based on four stationary models,this study investigates the fluidic and thermal performances of the wedge-shaped channels under the rotational condition and analyzes the effects of the configurations and arrangements of the turbulators on the heat transfer enhancement.The results show that the rotating wedge-shaped channels provide about 20% higher thermal performance than that of the stationary wedge-shaped channel.The turbulence intensity of the fluids is promoted by the Coriolis force and centrifugal buoyancy induced by rotation and is more intense than the fluid mixing generated by the turbulators of the channel.Therefore,the configurations and arrangements of the turbulators have little influence on the heat dissipation of the wedge-shaped channel.Moreover,rotation contributes to the movement of majority of fluids towards the trailing wall and the formation of low-momentum vortices near the leading wall,which results in approximately 35% more heat removal capability achieved by trailing wall relative to leading wall.