Calculation of Blade-Vortex Interaction of Rotary Wings in Incompressible Flow by an Unsteady Vortex-Lattice Method Including Free Wake Analysis

Röttgermann, A.; Behr, R.; Schöttl, Ch.; Wagner, Stefan

doi:10.1007/978-3-663-14005-4_15

Cited by 10 publications

(6 citation statements)

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“…(9) and the source terms, Eqs. (14) and (15). First the formulation for the velocities is presented where a distinction between sources and targets is made.…”

Section: Fast Multipole Methodsmentioning

confidence: 99%

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Vortex Preservation Using Coupled Eulerian–Lagrangian Solver

Huntley

Jones

Gaitonde

2019

Journal of Aircraft

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This paper presents a coupled Vortex Particle Method-Computational Fluid Dynamics solver. The Vortex Particle Method is used to prevent dissipation of the vortex structure on coarse CFD meshes. Implementation of the approach uses the Split Velocity Method that specifies the fluid velocity as the sum of the induced vortex particle velocity and a remaining velocity. Dissipation of the vortex velocities on coarse meshes is removed and the CFD equations solved for the remaining velocity have an identical form to those for a moving mesh, but with additional source terms. The coupled solver is demonstrated on a selection of two-dimensional test cases and the results are compared to the solutions of the CFD solver on its own using a coarse mesh and a fine mesh. It is shown that the coupled solver preserves the vortices on a coarse mesh and is computationally more efficient than using the fine mesh.

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“…(9) and the source terms, Eqs. (14) and (15). First the formulation for the velocities is presented where a distinction between sources and targets is made.…”

Section: Fast Multipole Methodsmentioning

confidence: 99%

“…Lattice methods are the most widely used method for rotor wake prediction to represent the shed and trailed vorticity generated by the rotor, see for example Röttgermann et al [15] and the study by Padakannaya [16]. Vortex Particle…”

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confidence: 99%

Vortex Preservation Using Coupled Eulerian–Lagrangian Solver

Huntley

Jones

Gaitonde

2019

Journal of Aircraft

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“…The effort that is necessary to correctly reproduce the vortex system differs for the different computational methods that can be applied for the analysis. In the case of a vortex-lattice method [3,4], for instance, the vortex system is directly obtained from the interaction of the vortex filaments that are shed from the blade. Thus, no vortex dissipation at all is present and BVI effects can be reproduced with a comparatively low computational effort.…”

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confidence: 99%

Tip Vortex Conservation on a Helicopter Main Rotor Using Vortex-Adapted Chimera Grids

et al. 2007

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This paper presents a method to improve the tip vortex conservation in a computational fluid dynamics simulation of a helicopter main rotor. Our approach uses vortex-adapted Chimera child grids to achieve a local refinement of the grid in the vicinity of the vortex and thus reduce the numerical dissipation of the vortex. The method is applied to the higher-harmonic-control aeroacoustic rotor test case to evaluate its potential with respect to the prediction of bladevortex interaction airloads. To allow a meaningful comparison with the experimental data, the rotor is trimmed for thrust, as well as for longitudinal and lateral mast moments, using weak fluid-structure coupling with a flight mechanics code. We obtained a good overall agreement with the experimental data for both aerodynamics and blade dynamics. The effect of the improvement in tip vortex conservation is demonstrated by comparison with simulations without Chimera refinement and with the experimental results. It turned out that a very fine grid resolution in the vicinity of the vortex is necessary to capture the blade-vortex interaction airloads. The required grid resolution was provided by a refinement of the vortex-adapted grids, allowing for a very good reproduction of the blade-vortex interaction airloads, especially on the retreating blade side. Nomenclature C m Ma 2 = sectional pitching moment coefficient C n Ma 2 = sectional normal force coefficient F z = rotor thrust, N Ma tip = hover tip Mach number M x = rotor mast rolling moment, Nm M y = rotor mast pitching moment, Nm q = rotor shaft angle, deg c = longitudinal cyclic pitch angle, deg s = lateral cyclic pitch angle, deg 0 = collective pitch angle, deg 3=rev = three-per-revolution higher-harmonic-control amplitude, deg = advance ratio = rotor azimuth angle, deg w = wake age, deg 3=rev = three-per-revolution pitch control phase, deg

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“…The DLM offers a faster way of computing unsteady aerodynamic loads, but it is a linear method restricted to small out-ofplane harmonic motions with a flat wake. Hence, while the DLM has dominated in fixed-wing aircraft aeroelasticity, the UVLM has been gaining ground in situations where free-wake methods become a necessity because of geometric complexity, such as flapping-wing kinematics [69][70][71], rotorcraft [72,73], or wind turbines [74][75][76][77][78][79][80]. With the advent of novel vehicle configurations and increased structural flexibility for which the underlying assumptions of the DLM no longer hold, the UVLM constitutes an attractive solution for aircraft dynamics problems and has been recently exercised in problems such as unsteady interference [53,81], computation of stability derivatives [82], flutter suppression [83], gust response [8,84], optimisation [85], morphing vehicles [86], and coupled aeroelasticity and flight dynamics [18].…”

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confidence: 99%