New free-wake analysis of rotorcraft hover performance using influence coefficients

Quackenbush, Todd R.; Wachspress, Daniel A.; Bliss, Donald B.

doi:10.2514/3.45885

Cited by 23 publications

(12 citation statements)

References 4 publications

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“…These wake instabilities are not to be confused with the stability of the numerical solution algorithm and it is possible to use a stable numerical algorithm to calculate the wake geometry in its unstable equilibrium state (Refs. 7,8). Therefore, the wake integration algorithm must be carefully chosen to avoid numerical instabilities.…”

Section: Vorticity Embedding Helix-ia Codementioning

confidence: 99%

Development of a CFD-Based Hover Performance Prediction Tool for Engineering Analysis

Bhagwat¹,

Moulton²,

Caradonna³

2007

j am helicopter soc

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This paper concerns the development of a second-generation implementation of the vorticity embedding method for the prediction of rotor hover performance. The basic method, encoded in the HELIX-IA code, is an Eulerian-Lagrangian, computational fluid dynamics (CFD)-based procedure that utilizes an Eulerian potential flow solution combined with a Lagrangian wake convection. The blade(s) can be represented either as a lifting-surface or as a lifting-line with a specified circulation (loading) distribution. Furthermore, the basic method is hybridized with a Reynolds averaged Navier-Stokes (RANS) code, TURNS. The HELIX-IA code provides the wake convection and associated induced inflow while the TURNS code provides the surface viscous flow. The method is grid point efficient because the CFD solver is not burdened with resolving the entire shed wake. The importance of recent enhancements to the basic HELIX-IA methodology is demonstrated by a good comparison of predictions (performance, loading and wake trajectory) with available model scale data. Application of the new hybrid option of HELIX-IA to the UH-60A Black Hawk rotor provides a first demonstration of this method. Convergence of the hybrid solution is good, showing the basic viability of the approach. Preliminary computations showa strong dependence of wake trajectory on tip loading, and the need for tip grid improvement in order to attain better accuracy. * Corresponding author; email: bhagwat@merlin.arc.nasa.gov. Manuscript Abbreviations AFapproximate factorization ADI alternating direction implicit CFD computational fluid dynamics FM figure-of-merit RANS Reynolds averaged Navier-Stokes

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Section: Vorticity Embedding Helix-ia Codementioning

confidence: 99%

Development of a CFD-Based Hover Performance Prediction Tool for Engineering Analysis

Bhagwat¹,

Moulton²,

Caradonna³

2007

j am helicopter soc

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“…Numerical solution of free wake methodologies have been studied over decades, including relaxation schemes [31e34] and time-marching schemes [35,36]. The time-marching methods can potentially present the best level of approximation to the rotor wake problem with the fewest restrictions in application.…”

Section: Aerodynamic Modelmentioning

confidence: 99%

Multi-objective optimization of wind turbine blades using lifting surface method

Shen

Chen

Zhu

et al. 2015

Energy

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a b s t r a c tThis paper describes a multi-objective optimization method for the design of horizontal axis wind turbines using the lifting surface method as the performance prediction model. The aerodynamic code for the design method is based on the lifting surface method with a prescribed wake model for the description of the wake. A multi-objective optimization algorithm approach is employed for the optimization of wind turbine blades with 3D stacking line (swept leaned blades). The (NSGA II) Nondominated sorting genetic algorithm II is used to facilitate the multi-objective optimization and to find the global optima of high-dimensional problems. The scope of the optimization method is to achieve the best trade off of the following objectives: maximum of annual energy production and minimum of blade loads including thrust and blade rood flap-wise moment. To illustrate how the optimization of the blade is carried out the procedure is applied to NREL Phase VI rotor. The result shows the optimization models can provide more efficient designs.

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“…To this end, numerous free-wake solution methodologies have been developed over the past two decades, including relaxation approaches (e.g., Refs. [7][8][9][10][11][12][13][14][15] and time-marching schemes (e.g., Refs. [16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Accelerated, high resolution free-vortex wakes for rotor aeroacoustic analysis

Bagai

Leishman

Glenn³

1997

15th Applied Aerodynamics Conference

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Numerical acceleration algorithms have been developed to improve the computational efficiency of rotor free-vortex wake analyses. Two general methodologies were formulated: an adaptive grid sequencing algorithm, and a velocity field interpolation algorithm. The methods were found to produce up to an order of magnitude decrease in execution time, but without significant loss in predictive accuracy. Examples are shown for very high fidelity wake geometries required for rotor aeroacoustic analyses.

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New free-wake analysis of rotorcraft hover performance using influence coefficients

Cited by 23 publications

References 4 publications

Development of a CFD-Based Hover Performance Prediction Tool for Engineering Analysis

Development of a CFD-Based Hover Performance Prediction Tool for Engineering Analysis

Multi-objective optimization of wind turbine blades using lifting surface method

Accelerated, high resolution free-vortex wakes for rotor aeroacoustic analysis

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