Method for Calculating Rotors with Active Gurney Flaps

Abstract

This paper builds on the Helicopter Multi-Block version 2 CFD solver of the University of Liverpool and demonstrates the implementation and use of Gurney flaps on wings, and rotors. The idea is to flag any cell face within the computational mesh with a solid, no slip boundary condition. Hence the infinitely thin Gurney can be approximated by "blocking cells" in the mesh. Comparison between thick Gurney flaps and infinitely thin Gurneys showed no difference on the integrated loads, the same flow structure was captured and the same vortices were identified ahead and behind the Gurney. The results presented for various test cases suggest that the method is simple and efficient and it can therefore be used for routine analysis of rotors with Gurney flaps. Moreover, the current method adds to the flexibility of the solver since no special grids are required and Gurney flaps can be easily implemented. Simple 2D aerofoil, 3D wing, and rotors in hover and forward flight were tested with fixed, linearly actuated, and swinging Gurneys, and the ability of the code to deploy a Gurney flap within the multiblock mesh is highlighted.

Experimental assessment of an active L-shaped tab for dynamic stall control

“…Both experimental and numerical activities agree that the lift enhancement mechanism of a Gurney flap can be useful to improve blade aerodynamic performance (Maughmer and Bramesfeld, 2008;Yee et al, 2007). Indeed, numerical studies report that benefits for rotorcraft performance can be obtained by the use of an active Gurney flap deployed on the retreating side of rotor disk and retracted on the advancing side (Yeo, 2008;Woodgate et al, 2016). Nevertheless, as also sustained by experimental results described in Chandrasekhara et al (2008), a deployable Gurney flap is not expected to have valuable effect in terms of pitching moment peak reduction as the previously cited leading edge devices because, acting at trailing edge region, it should have a very limited effect of vortical structures typical of the dynamic stall process that are generated by flow separations occurring at leading edge (McCroskey, 1981;Leishman, 2006).…”

“…Among all these studies, the interest about the effects of a Gurney flap (Liebeck, 1978) on rotor blades (Kentfield, 1993) has recently grown, as demonstrated by the several works about the study of the potential effect of an active deployable Gurney flap (see, for instance the works by Yeo (2008); Kinzel and Maughmer (2010); Woodgate et al (2016)). Both experimental and numerical activities agree that the lift enhancement mechanism of a Gurney flap can be useful to improve blade aerodynamic performance (Maughmer and Bramesfeld, 2008;Yee et al, 2007).…”

Optimisation of Ducted Propellers for Hybrid Air Vehicles Using High-Fidelity CFD

“…8a). The radiators and coolers were included in the CFD simulations as infinitely thin walls, by setting up a solid wall boundary at the interface between two adjacent grid blocks (34) . The location of these thin walls, which must have rectangular shape, is specified by giving their corner point coordinates.…”

Simulation of Tail Boom Vibrations Using Main Rotor-Fuselage Computational Fluid Dynamics (CFD)

“…Also, a sliding-mesh method is implemented so that test cases with relative motions of different parts of the geometry can be modeled. The HMB method has been validated for a range of rotorcraft applications [13][14][15][16][17][18] and has demonstrated good accuracy and efficiency for very demanding flows. The parallel implementation makes use of the Message Passing Interface library for inter-processor communication and of parallel I/O for saving and reading data from out-of-core storage.…”