Abstract
Aerodynamic characteristics of helicopter engine side air intakes are investigated. The experimental data set is obtained by wind tunnel testing of a full-scale helicopter fuselage section model. For the simulation of realistic engine operation, engine mass flow rates are reproduced. Five-hole pressure probe data of the aerodynamic interface plane as well as local surface pressure distributions are compared for different geometries and operation conditions. Previous investigations indicate that unshielded, sideways-facing air intakes yield lowest distortion and highest total pressure levels in low speed conditions. In fast forward flight condition, however, forward-facing intake shapes are more beneficial. On this basis, the current research assesses the optimization potential of retrofit modifications such as a rear spoiler (small scoop) and an intake guide vane. Two optimal configurations of retrofit modifications are identified, combining benefits of the various basic intake and plenum chamber shapes.
Highlights
Helicopters play an essential role in air transport on the basis of their unique vertical take-off and landing (VTOL) abilities
Main influences of rear spoilers with variable heights and lengths as well as an intake guide vane at three different streamwise positions are investigated as retrofit modifications for the baseline configuration
The variation of mass flow rates has a minor effect on the coefficients comparing to freestream velocities and is not regarded in the current research
Summary
Helicopters play an essential role in air transport on the basis of their unique vertical take-off and landing (VTOL) abilities. In certain situations and applications such as search and rescue (SAR) missions, lightweight helicopters prevail over fixed-wing aircraft. The reduction of emissions is a crucial aim. For this purpose, aerodynamic optimization of the fuselage shape is performed [1] as well as optimization of the engine installation [2]. One means is to enhance compressor inflow conditions. As reference plane for the evaluation of the inflow conditions, the aerodynamic interface plane (AIP) is applied. For this plane, evaluation parameters like a distortion parameter
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