Study On Particle Deposition,Flow And Heat Transfer In Internal Cooling Channel Of Turbine Blade

When marine gas turbines work in a high-salt and high-humidity marine environment for a long time,some impurity particles will be carried in the gas flowing out of the compressor.These particles may deposit on each surface of the cooling channel inside the turbine blade of the gas turbine,resulting in the decline of the heat transfer performance of the turbine,thus affecting the safe operation and service life of the Marine gas turbine.Therefore,in order to better strengthen the flow heat transfer in the internal channels of gas turbines,improve the cooling performance of the internal cooling channels on the blades,ensure the service life of the vanes and improve their environmental adaptability,it is necessary to take into account the impact of corresponding pollutant deposition in the design of the cooling channels in high-temperature turbines.In this paper,based on the kinetic characteristics of particles carried by the gas flowing out of the compressor,entering the cooling channel inside the cooling turbine and the interaction characteristics between particles and the wall,a deposition model based on the influence of velocity field was established based on the high-temperature wall,and the nesting of the deposition model and CFD program was realized by using the user-defined function.The internal cooling channel of marine gas turbine is simplified as single channel of flat rib and U-shaped flat channel,BSL k-ω turbulence model is used to simulate the continuous phase of internal channel,and Lagrangian method is used to track the particle trajectory.The effect of rib shape on heat transfer and particle deposition of a single channel is studied.The results show that the reduction of the rib inclination angle can make the fluid form transverse secondary flow on the intercostal wall,which leads to the enhancement of the heat exchange capacity between the fluid and the wall,and changes the normal velocity and tangential velocity of particles when they collide with the wall,thus affecting the deposition of particles on the intercostal wall.With the increase of intercostal space,the fluid contact with the wall surface in the intercostal area becomes more sufficient,the area of particle contact with the wall surface becomes larger,the particles collide with the intercostal wall surface and the amount of deposition increases.The ratio of rib height to width changed the fluid disturbance,affected the heat transfer capacity between the main flow and the wall,and changed the impingement and deposition of particles in the intercostal wall.For the U-shaped flat channel,the main research is 7 different rib angles and 1 type of rib structure with guide vanes at the elbow.The research results show that changing the inclination angle of the downstream rib can improve the deposition of particles on the side wall of the elbow,but will not improve or adversely affect the deposition on the side wall of the elbow.The increase of the U-shaped flat channel of the deflector can make the elbow the amount of deposition on the sidewall surface is reduced.And when the angle between the air film hole and the wall is β=90°,the downstream rib inclination angle α is different(α=30°,45°,60°,75°,90°),and the downstream rib inclination angle α=60°,when the angle βbetween the air film hole and the wall is different(β=30°,45°,60°,75°,90°),the flow and heat transfer performance and particle deposition under eight different internal cooling structures.The results show that the u-shaped rib channel with a downstream rib angle ofα=60° and an angle between the air film hole and the wall surface of β=45° has the lowest deposition rate on the curved wall and the best heat transfer performance among the eight internal cooling structures,which can effectively improve the marine environmental working adaptability of the marine gas turbine cooling turbine and reduce the particle deposition in the internal cooling channel.In this paper,the numerical simulation method is used to study the particle deposition and heat transfer characteristics in straight rib single channel and U-shaped plate channels.Based on the original critical velocity deposition model,a new deposition model is developed to increase the critical tangential velocity of particles impinging on the wall and further enrich the sedimentary model.The conclusions about the heat transfer and particle deposition in the wall of the gas turbine internal cooling channel are obtained,which provides a theoretical basis for the design of the gas turbine internal cooling channel in the future.