Navier-Stokes Prediction of the Effect of the Skids on the Aerodynamics of Helicopter Fuselage in Forward Flight

A series of three-dimensional Navier-Stokes computations were carried out with and without skids to investigate the influence of the skids on the flow field and aerodynamic forces acting on a helicopter fuselage in low Mach number forward flight under different pitch angles. All the numerical results presented in the paper were produced using multi-block structured grids and a finite volume approach. The computed aerodynamic forces were significantly improved with respect to their experimental counterparts by the inclusion of the skids in the computational model

NUMERICAL ANALYSIS OF HUB AND FUSELAGE INTERFERENCE TO REDUCE HELICOPTER DRAG

A numerical investigation was carried out to predict the mutual interference between helicopter components. The investigation was based on the solution of RANS equations in three dimensions using unstructured grids. Results are presented for six different test cases under steady forward flight conditions at Mach number equal to 0.204. These test cases refer to different combinations of reduced scale models of helicopter fuselage, rotor hub and main rotor modelled by an actuator disc. Analysis of the results revealed that while significant correlation between the hub and fuselage loads, and a non trivial influence of the actuator disc on these loads could be observed, the drag breakdown of the hub was not effectively altered

Computational Investigation of Advanced Hub fairing Configurations to Reduce the GRC2 Common Platform Helicopter Drag

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Drag reduction of a transport helicopter by application of an adjoint-based fuselage optimization chain and modification of the rotor head

In this paper two approaches are investigated to reduce the parasite drag of a helicopter. The first approach is to optimize the surface of the fuselage back door. This is done by applying an automatic, adjoint-based optimization chain; developed by DLR for these purposes. This optimization chain combines the RANS-solver TAU with a solver for the discrete adjoint equation and a conjugate-gradient based optimization algorithm. The parameterization is done by Free Form Deformation. A description of the functionality of the chain is given, before the results of the optimization run are presented. The resulting surfaces were able to bring benefits, up to 3.75% drag reduction compared to the baseline geometry. The second approach is to reduce the main rotor head drag, by installing a hub fairing. During this investigation, two different hub geometries were tested. By using a fully closed fairing, a drag reduction of about 19% could be achieved

CFD Prediction of Air Flow Past a Full Helicopter Configuration

The present study is one of the first attempts to exploit the GOAHEAD data base to perform a code-tocode evaluation on complete helicopter aerodynamics. The numerical results of two GOAHEAD partners, the German Aerospace Center (DLR) and Politecnico di Milano (PoliMi) are presented and compared to experimental measurements. The study also addresses an evaluation of two different approaches to predict helicopter flows. The first, applied by DLR, accounts for rotor trim and elastic effects by weak fluid–structure coupling. The PoliMi approach, on the other hand, enforces a prescribed kinematics, taken directly from the experiment, on a rigid blade. The simulations refer to a complete helicopter wind– tunnel model, featuring a scaled NH90 fuselage, the ONERA 7AD main rotor, a scaled BO105 tail rotor, a rotor hub and a pylon, all located inside the 8 m × 6 m test section of the DNW low-speed wind tunnel. The flight conditions correspond to cruise flight at Ma = 0.204 and fuselage attitude α = −2.5◦. The comparisons demonstrate the capability of present unsteady RANS solvers to predict flow fields around complete helicopters