Flow Analysis of a Helicopter Engine Side Air Intake

Abstract

A detailed experimental and numerical investigation on the flow characteristics of an engine side air intake of a lightweight helicopter is conducted. The experimental dataset is obtained in a comprehensive wind-tunnel campaign on a novel full-scale model of a helicopter fuselage section. In the wind-tunnel tests, engine mass flow rates corresponding to realistic helicopter operating conditions are reproduced. For fast forward-flight conditions, five-hole pressure probe data in the aerodynamic interface plane as well as local surface pressure distributions are compared with the data obtained by unsteady Reynolds-averaged Navier–Stokes simulations. Regarding the corresponding numerical sectional fuselage case, all components of the wind tunnel model and the essential wind tunnel parts are comprised. To assess the influence of the truncation of the fuselage, an additional full fuselage case is investigated. A good agreement of the numerical simulations and the wind-tunnel data is achieved. The investigation of the side intake geometry yields a distorted total pressure distribution in the aerodynamic interface plane with regions of high and low total pressures. The origin of the aerodynamic interface plane total pressure distribution is explained in detail, analyzing the flow topology in the inlet region and the engine intake duct.