Performance Deterioration of Rotorcraft Engines fitted with Particle Separators

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Military rotorcraft engines operating in harsh environments routinely ingest large quantities of mineral dust, which can degrade components and ultimately reduce operability. Time off-wing for unscheduled maintenance is a costly burden, both financially and operationally. Rapidly predicting engine deterioration rates as a function of the mission presents an opportunity to optimise flow of supplies, better manage fleets, and perform safety risk assessments when dust loading is expected to be particularly high. In the current contribution, we present our ongoing efforts in this field with a new methodology for assessing the effectiveness of inertial particle separators and quantifying the changes they impart to the inbound dust. We demonstrate that both the concentration reduction and the modification to the particle size distribution can be made on the basis of a single independent variable - a generalised Stokes number for inertial particle separators - and a single performance parameter - the corrected separation efficiency. To develop these parameters we conduct numerical simulations of the flow through a generic axi-symmetric inertial particle separator, over a range of five mass flow rates, three scavenge mass flow rates, and 16 particle diameters. In addition to this, a framework is presented to enable an estimation of the dust concentration at the engine intake. This is achieved by correlating the total wake strength to an existing dust landing trial dataset. A coupled rotorcraft-engine model is then used to combined the two methodologies to investigate the influence of engine mass flow rate on dust ingestion rate. A weak non-linear relationship is observed, which arises due to the simultaneous increase in wake strength with engine mass flow rate as rotor power requirements increase. The additional dust stirred up by the stronger wake leads causes this non-linearity. Finally, we show that an improvement in separation efficiency caused by higher engine mass flow rate is far outweighed by the associated increase in dust loading in this condition.

Bibliographical metadata

Original languageEnglish
Title of host publicationVertical Flight Society Forum 76
Publication statusAccepted/In press - 2 Oct 2020