Simulations of Multiphase Particle Deposition on a Gas Turbine Endwall With Impingement and Film Cooling

Abstract

Replacing natural gas fuels with coal derived syngas in industrial gas turbines can lead to molten particle deposition on the turbine components. The deposition of the particles, which originate from impurities in the syngas fuels, can increase surface roughness and obstruct film cooling holes. These deposition effects increase heat transfer to the components and degrade the performance of cooling mechanisms, which are critical for maintaining component life. The current study dynamically simulated molten particle deposition on a conducting blade endwall with the injection of molten wax. The key non-dimensional parameters for modeling of conjugate heat transfer and deposition were replicated in the experiment. The endwall cooling arrangements included film cooling only as well as internal impingement jet cooling plus film cooling. The distribution of deposition was influenced by the film cooling blowing ratio as well as the surface temperature of the endwall. Increasing blowing ratio mitigated some deposition at the film cooling hole exits and in areas of coolest endwall temperatures. After deposition, the external surface temperatures and internal endwall temperatures were measured and found to be warmer than the endwall temperatures measured before deposition. Although the deposition helps insulate the endwall from the mainstream, the roughness effects of the deposition counteract the insulating effect by decreasing the benefit of film cooling and by increasing external heat transfer coefficients.