Analysis Of The Effect Of Roughness On The Flow And Heat Transfer Of Turbine Blade Double Wall Cooling Structure

With the increasingly widespread application of gas turbines in fields such as aviation,ships,and power generation,people have put forward higher requirements for the performance of gas turbines.From the perspective of the gas turbine cycle mechanism,increasing the gas temperature before the turbine is beneficial for improving the performance of the gas turbine.At present,the gas temperature in front of the turbine is much higher than the tolerance temperature of the turbine material.Therefore,in order to ensure the reliability of hot end components,it is necessary to develop advanced composite cooling structures such as double wall cooling structures.When a gas turbine operates in environments containing salt,sand,and severe pollution,external fine particles entering the engine flow channel are prone to deposit in the complex cooling channel,resulting in changes in the flow and heat transfer characteristics of the turbine blade cooling channel.This article takes the double wall cooling structure as the research object,and studies the influence of particle deposition roughness inside the double wall cooling structure on flow and heat transfer characteristics through numerical simulation.It summarizes the influence law of roughness on flow and heat transfer characteristics of the double wall cooling structure.The main research content of this article is as follows:1.Establish a double wall cooling structure model based on geometric parameters,verify grid independence and turbulence model validation with experimental values,and determine the effectiveness of the calculation model and numerical simulation scheme.The flow and heat transfer characteristics of smooth laminar structures at two scales,the original model and the scaled up model,with different height to diameter ratios and positions of the disturbance columns at a blowing ratio of 0.3 to 1.5,were numerically simulated and calculated.2.Based on existing research data,determine the roughness of the inner cavity and gas film hole surface of the double wall cooling structure with different roughness areas.Set different uniform roughness values for the inner cavity and gas film hole,calculate the flow and heat transfer characteristics under different conditions in the above structure,analyze the internal flow field situation,and study the influence of roughness on flow and heat transfer.3.The target surface of the double wall cooling structure is divided into two parts: the film hole and the opposite impact hole,and different roughness values are set for calculation.The changes of the flow field and cooling performance inside the double wall cooling structure are analyzed,and the influence of the location of the roughness degree distribution on the flow and heat transfer of the double wall cooling structure is summarized.The results indicate that the cooling efficiency of the double wall cooling structures increases with the increase of blowing ratio;The cooling efficiency first increases and then decreases with the increase of the height to diameter ratio of the pin fin;Compared with the pin fin located on the impact surface,the cooling efficiency of the pin fin located on the target surface is higher,and this advantage becomes more significant as the blowing ratio increases;The cooling efficiency of different scale double wall cooling structures with added roughness in the middle chamber and gas film hole shows a trend of first increasing and then decreasing with the increase of roughness;When the roughness is non-uniformly distributed,the resistance coefficient,flow coefficient,and cooling efficiency of the double wall cooling structure generally change regularly with the increase of the average roughness of the parameter.The cooling efficiency is highest when the average roughness of the parameter is around 40.