Numerical and Experimental Investigation of a Helicopter Engine Side Intake

Aerodynamic characteristics of an engine side intake of a light helicopter are investigated experimentally and numerically with an emphasis on fast forward flight (Ma < 0.2). For this purpose, a novel full scale model of a helicopter fuselage section has been developed and tested. With a duct system, including a fan, engine mass flow rates are realized corresponding to real helicopter operating conditions. The wind tunnel data comprise aerodynamic interface plane (AIP) five-hole pressure probe and particle image velocimetry data which are compared to unsteady Reynolds-averaged Navier-Stokes simulations results. In order to assess the influence of the truncation of the fuselage, two numerical cases are compared. The first is a sectional fuselage case, incorporating all wind tunnel model components, and influential wind tunnel parts. The second is a full fuselage case. Only small differences between the sectional and full fuselage cases in flow direction upstream of the intake are present whereas the AIP total pressure distributions provide the same characteristics. The experimental data are also used to validate the numerical simulations while the complementary experimental and numerical data enables a detailed analysis of the flow distortion up to the AIP.