Study On The Law Of Particulate Deposition At Endwall Of Turbine

In the operation of aviation gas turbine engines,the particles from the outside atmosphere and the particles in the fuel may not be fully burned in combustion,and the formed molten particles may deposit on the turbine blades.and the endwall,thereby increasing the roughness of the flow surface in the turbine,so it will increase the airflow splitting phenomenon.And the particles deposited on the surface will affect the cooling effect for the turbine.More seriously,the deposition maybe block the film cool of the turbine,it will not only affect the cooling efficiency of the film cooling,but also can cause the failure of the turbine components or the failure of the entire engine when the deposition reaches a certain scale.The simulation calculation of deposition distribution and thickness on turbine components has certain reference value for the subsequent life prediction of turbines.This paper mainly uses the discrete term DPM in Fluent to simulate particle incidence and calculate the motion of particles in the turbine.Based on the adhesion of particles,the particle detachment conditions are proposed.The force is analyzed mainly for the particles adhering to the wall surface,and the particle detachment condition is judged by the value for the moment of flow resistance and viscous force between the particles and wall.And the appropriate mesh reconstruction process is written by C# to simulate the unsteady deposition process,so that the volume adjusted by the mesh is equal to the volume of the particle deposition,so as to accurately obtain the deposition distribution and deposition thickness of the particles on the turbine endwall.In this paper,the paraffin particle deposition experiment was used to verify the particle deposition mechanism,and the simulation was carried out under the condition of detachment.It is found that the particles are peeled off on both sides of the flat film hole.Through the study of the deposition of particles inside the turbine,it is found that the deposition thickness at the stagnation point of the leading edge of turbine endwall is the largest,and the increase of the mainstream temperature will reduce the deposition thickness of the particles at the stagnation point.Due to the influence of the internal passage vortex of the turbine,the deposition of particles on the pressure side is more than the deposition of the suction side.Due to the velocity of the fluid at the trailing edge endwall is faster than pressure side,the amount of detachment of the particles at the trailing edge is greater.For endwall studies with film holes,it has been found that cold flow will hinder particle deposition,but the amount of particle deposition between the film holes will increase.In general,the UDF is used to bring the deposition mechanism into the calculation process of the deposition,and the adjustment of the moving mesh can more accurately obtain the deposition phenomenon of the turbine surface,so as to facilitate the study of the deposition phenomenon on the internal airflow and heat transfer of the turbine influences.