Aerodynamic characteristics of helicopter engine side air intakes

Purpose: Aerodynamic characteristics of engine side air intakes for a lightweight helicopter are investigated aiming to achieve an efficient engine airframe integration. Design/methodology/approach: On a novel full-scale model of a helicopter fuselage section, a comprehensive experimental data set is obtained by wind tunnel testing. Different plenum chamber types along with static side intake and semi-dynamic side intake configurations are considered. Engine mass flow rates corresponding to the power requirements of realistic helicopter operating conditions are reproduced. For a variety of freestream velocities and mass flow rates, five-hole pressure probe data in the aerodynamic interface plane and local surface pressure distributions are compared for the geometries. Findings: In low-speed conditions, unshielded, sideways facing air intakes yield lowest distortion levels and total pressure losses. In fast forward flight condition, a forward-facing intake shape is most beneficial. Additionally, the influence of an intake grid and plenum chamber splitter is evaluated. Originality/value: The intake testing approach and the trends found can be applied to other novel helicopter intakes in early development stages to improve engine airframe integration and decrease development times.