The Flow And Heat Transfer Characteristics Of The Cooling Lamilloy Of The Leading Edge Of The Turbine And The Heat Transfer Mechanism Of The Dimple

The performance of gas turbine has a significant impact on the safety and economy of the aircraft engine because high-temperature gas turbine is the key component of the aircraft core engine.The pursuing of high thrust-weight ratio and high efficiency of aircraft engine leads to the gradual rising of the temperature of gas turbine inlet.It makes the gas turbine cooling technology more challenging for higher output power requirements and higher thermal efficiency.In this study,the heat transfer mechanism of the leading edge region of a high temperature turbine vane and blade in a high thrust-weight ratio aero-engine is focused on.A leading edge region cooling structure of gas turbine design platform is established by in-house code.The internal heat transfer and flow structure characteristics on typical cooling structure element are numerically studied.Firstly,the influence of the curvature and the nozzle to target surface distance of a Lamilloy cooling structure of the leading edge of the turbine vane and blade is studied.The results show that the change of the curvature of the leading edge of the turbine vane and blade and the nozzle to target surface distance can significantly affect the heat transfer performance of the impingement target surface.Secondly,the effects of pin fin configurations and dimple parameters on the heat transfer and friction factor characteristics in a Lamilloy cooling structure of the leading edge of the turbine vane and blade are also performed.The results show that the pin fin arrangement changes the thermal perforamce mechanism and the optimal pin fin layout is concluded.In addition,the dimple is introduced in the typical Lamilloy structure of the leading edge of the turbine vane and blade.It is found that the adoption of dimple in the Lamilloy cooling structure of the leading edge increases the heat transfer of the target surface to some degree and reduces the friction factor.However,the dimple with big depth or diameter will reduce the heat transfer of the target surface dramatically.In addition,the changing shape of the dimple has little influence on the heat transfer performance of the target surface.Furthermore,the influence of the curvature of the leading edge of the turbine and the nozzle to target surface distance on the heat transfer of the Lamilloy cooling structure of the leading edge of the turbine vane and blade with a dimple structure is carried out.The results show that the change of the curvature of the leading edge and the nozzle to target surface distance can significantly affect the heat transfer caused by the thinning of the flow boundary layer after the flow leaving from the stagnation point of the dimple.The curvature of the leading edge region and the nozzle to target surface distance are not linearly related to the heat transfer enhancement of the target surface.Finally,the method of circular hole jet impingement cooling is used to simulate the local heat transfer in the leading edge region of the turbine vane and blade.It is found that the Reynolds number of the cooling air inlet,the film hole to the impingement hole diameter ratio,the curvature of the leading edge of the turbine vane and blade,the nozzle to target surface distance,the pin fin and dimple structure parameters have different effects on the heat transfer performance of the impingement target surface.Through the analysis and research of a large number of numerical simulation data,the general empirical formula based on the average heat transfer characteristics of Dittus-Boelter for the dimensionless parameters of the leading edge of the turbine vane and blade is compiled.