Study On Heat Transfer Characteristics Of Pin Fins In Gas Turbine Blade Trailing Edge

The pin fin cooling measure is the mainstreams of the gas turbine blade trailing edge cooling measures,the fluid flow moves round the pin fin to produce horseshoe vortex and the fluid boundary layer begins separating,the turbulent wake in the back of pin fin increases cooling gas turbulence,and disturbs the development of fluid boundary layer on downstream pin fin surface.the superposition of the disturbance of air conditioning along upstream and downstream mainstreams increases the heat transfer performance,in addition to disturbing the flow,pin fin also transferring the heat from the surface.Therefore,the heat transfer design of the pin fin arrays is a great significance to the optimization of the overall cooling scheme in the gas turbine blade trailing edge.However,the influence of solidity degree on the heat transfer in the pin fin cooling study has been neglected by the Chinese and foreign scholars,their main research also focuses on the 12.5%~24% solid degree,and there is little research about the heat transfer of the high solid(greater than 40%)pin fin arrays.In this paper,the numerical simulation is adopted to researching the heat transfer characteristics of different solidity degrees pin fin arrays,the change of heat transfer of high solid pin fin arrays in the two types of channels is analyzed and compared,which provides a design reference for the overall cooling of blade trailing edge.This article firstly established the physical model of three different solid pin gin array,the channel type designed for constant channel,and the SST k-? turbulence model was adopted to numerically simulating the heat transfer and flow characteristics in different solid pin fin arrays after the mesh was be accurately established.According to the change of the flow structure in different solid channels,the influence of the changing solidity on the heat transfer performance and the pressure loss coefficient was explored.The result shows that with the increase of the solidity of the pin fin arrays,the width and the kinetic energy of the flow is reducing,and its own speed is becoming a periodic distribution.The area of the endwall is smaller,but the area ratio of the low temperature area with higher heat transfer efficiency is increased.The average heat transfer level of pin fin arrays with different solidity degrees increases exponentially with the increasing of the inlet Reynolds number,the high solidity array has a higher heat transfer effect,and there are two highest point appears in the upper and lower flow direction.The pressure loss coefficient decreases exponentially in different solidity degrees,the high solidity pin fin arrays decreased faster,and the pressure loss coefficient at high Reynolds number is the lowest,the pressure loss coefficient of the flow is first decreased and then increased.Based on the former part of the numerical calculation,choose the type of channel in high solidity to be the subsequent research direction,and individually designing and establishing the model about a convergent channel,to comparatively analyzed the distribution of cooling gas flow and the heat transfer characteristics in the rectangular channel,and further exploring the cooling performance in high solid pin fin arrays.The result shows that the type of channel changing will make a large influence about internal cooling gas flow field structure,the flow velocity becomes faster along the channel,its effect about pressure loss coefficient and the heat transfer has a more important part.The heat transfer effect is exponentially enhanced with the increasing of the inlet Reynolds number in convergent channel,which is higher than constant channel,the gap gradually narrowed,and the pressure loss coefficient decreases exponentially in convergent channels.Under the same inlet Reynolds numbers,different to the constant channel whose peak value of heat transfer occurs in the middle region,that the heat transfer of convergent channel increases continuously along the flow direction,although there is the same waved point about heat transfer,but the gap between the two channels increases gradually.The pressure loss coefficient of converging channel also shows a continuously upward trend.