Influence of Turboshaft Engine Architecture on Ash Particle Deposition: Reduced Order Model Application

Abstract

Particles ingested by aero gas turbines are capable of melting in the combustor and depositing on high pressure turbine vane surfaces, where they degrade aerodynamic and thermodynamic performance. The extent of the damage caused is a complex physical process dependent on the thermal and inertial properties of the particles, the operating state of the engine and importantly, engine architecture. The dominant architecture considerations are the position of the burner flames relative to the nozzle guide vane leading edges and the temperature difference across the burner flames. In this work, we investigate the influence of this on particle deposition by approximating the temperature variation of the hot streak as a sinusoidal profile. A parametric analysis is carried out using numerical simulations and an elastic-plastic particle deposition model, to evaluate the effect of mean temperature, temperature difference across the hot streak, and hot streak position on the deposition rate of a generic particle size distribution. Results show that the dominant effect driving particulate deposition is a combination of the gas temperature, hot streak position relative to the vane leading edge and the particulate type. The rate of deposition on a vane for sub-bituminous ash particles may be reduced by up to 56% if the combination of mean temperature, temperature difference across the hot streak, and hot streak position are chosen carefully.