On The Fluid Flow And Heat Transfer Mechanism Of Cooling Structure Of Leading Edge In Gas Turbine Blade

A ablation damage of turbine blades will be induced by the high gas temperature,especially for the blade leading edge which faces the mainstream gas directly,and thus decrease the reliability and safety of aeroengines.Therefore,develop a high-efficiency blade cooling technology,and further improve the heat transfer capacity of blade leading edge is of great significance to the development of aeroengine tenchnique.Jet impingement cooling and film cooling are the mainstream cooling technology in the blade leading edge,while the research on impingement cooling mainly focuses on the plate impingement and average value of concave surface,very limited data onthe fluid flow and heat transfer characteristics in concave impingement.Based on the above factors,the investigations on simplified model mechanism research,conjugated with other cooling structures mechanism research,actual blade verification are conducted to investigate the in this paper to study the effects of the arrangement of jet holes,film cooling,pin-fin,dimple on the flow and heat transfer.Firstly,the effect of slot jetimpingement,single array jets impingement and arrays jets impingement on a concave double-wall channel on the fluid flow and heat transfer characteristics were studied.The movement of main and sencondary flow and the revolution and interaction of main vorticies for array jets impingement were illustrated.With the near-wall flow characterictics analysis,the near wall flow characteristics were connected with the target local heat transfer,the mechanism of the parameters and arrangement effect of the jet holes on heat tranfer were revealed.The results shows that the scheme with larger curvature and smaller jet-to-target distance shows higher heat transfer,and the blocked effect between the main flow is weakened as the array jets columns are sparse,which is more conducive to heat transfer.Pin-fin and dimple are widely used in the blade channel heat transfer.In this paper,the pin-fin and dimple are applied to the single row jets impingement model to investigate the arrangement of pin-fin and dimple,height and position of broken pin-fin effect on the target heat transfer.The results shows that the arrangements of pin-fin/dimple staggered with the jet and broken pin-fin staggered posited on the upper wall show positive role in heat transfer enhancement.Film cooling technology is widely used in the design of turbine blade cooling structure as its characterictics in protect the blade surface from hot gas.In this paper,the number and arrangement of film holes effect on the channel fluid flow of jet impingement onto concave surface with bleedings are studied.The arrangement parameters influences on the target heat transfer are investigated with the near-wall flow characteristics picture.Futher more,the pin-fin,dimple and broken pin-fin are arranged in the impingement channel to enhance the heat transfer.The results show that the cases of inline posited film holes which is far from the jets and pin-fin located between jets and film holes show higher heat transfer.The research on the mechanism of cooling structures should be applied to the real blade design.The results of previous study on the ideal model of jet impingement of blade leading edge were used to a real turbine blade to evaluate the effect of the mechanism research.The results show that the average temperature of the blade leading edge decreases by 13 K after the jet holes are rearrangemented.It can be inferred that the mechanism research on the heat transfer enhancement of the leading edge double wall impingement channel is of practical significance for reducing the temperature of turbine blades.