Numerical Investigation of the Influences of External Flow on Sand Separation Characteristics of a Turboprop Inlet with a Scavenge Duct

Abstract

Inhalation of sand particles by aircraft engines can lead to erosion of the compressor and turbine blades and clogging of the cooling ducts. The existing research on engine sand protection primarily focuses on the turboshaft engine, leaving a gap in the field of turboprop engine sand protection. Consequently, this study focuses on the sand separation characteristics of a turboprop engine inlet equipped with a scavenge duct, using a validated numerical simulation method. The aerodynamic simulation uses the Reynolds-averaged Navier-Stokes (RANS) equations linked with the SST k-ω turbulence model, and the sand simulation uses the Discrete Phase Model (DPM) for sand trajectory tracking. Three numerical strategies, transient, quasi-steady, and steady, are investigated and compared with the experimental results to verify that the quasi-steady method best suits the current sand separation simulations with the best accuracy. It is found that the coarse sand particles have a high separation efficiency due to the inertia dominance, while the fine particles have a low separation efficiency due to the flow following nature. The parametric analysis shows that the separation efficiency decreases with the increasing propeller speed, but improves with increasing scavenge ratio (SCR). the flight velocity is negatively correlated with the separation efficiency of fine sand particles, but promotes that of coarse particles. This study reveals the interaction mechanism between aerodynamics and particle inertia, which provides an important basis for optimizing the design of turboprop swept-airway sand traps.

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