Research Of Deposition Model On Blade Surface Of Gas Turbine

For aviation engines, high temperature and high pressure gas flowing out from the combustion chamber contains some molten impurity particles, where there are two main sources: impurity particles(such as volcanic ash, etc.) doped in the intake gas and in the fuel.These molten particles could deposit onto the turbine blade, and in some cases block film cooling holes by entering into cool air duct, which will result in engine performance reduction.Based on two existing deposition model- critical viscosity model and critical velocity model,this article introduce a new deposition model and conduct some numerical simulations under different working conditions in order to verify the model’s feasibility and the impact of physical parameters on the blade surface deposition phenomenon.On the basis of two-phase flow theory, non-dimensional governing equations are established to obtain the distribution of particle temperature and velocity, which shows that the particle velocity and temperature are mainly impacted by physical and chemical properties of the particle and temperature field and velocity field of mainstream. The expression of deposition rate D are finally obtained.To the blade channel model without film cooling, the effect of mainstream inlet temperature and pressure ratio on deposition behavior was studied. Result shows that too high mainstream temperature will cause the blade surface temperature increase, which will result in augmentation of the particle capture efficiency( amount of particle deposited on blade surface to amount of particle injected) and range expansion of particle size allowing deposition. Too high pressure ratio will cause the blade surface temperature decrease, which will reduce the capture efficiency.Eventually, the impact of blowing ratio, injecting angle and hole diameter on deposition behavior under leading edge model and plate model was separately studied. Too low blowing ratio or injecting angle cannot blow off the particles from the blade surface, which will result in high impact efficiency(amount of particles impacting on the blade surface to amount of particles injected), and high blowing ratio or injecting angle will leads to the cold air awayfrom the surface, high surface temperature and high deposition efficiency( amount of particles depositing on the blade surface to amount of particles injected). So, the optimal blowing ratio and injecting angle exist so that the deposition amount is the smallest. The large hole diameter cause the particle away from the surface and reduction of particle temperature, which will result in low capture efficiency.