Exploring the Detached-Eddy Simulation for Main Rotor Flows

Dehaeze, F.; Barakos, George N.; Kusyumov, A. N.; Kusyumov, S. A.; Mikhaǐlov, S. A.

doi:10.3103/s1068799818010063

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…However, an inherent issue of these simulations is that the vortex features are prematurely deformed and dissipated due to the dissipative nature of numerical schemes, this makes the employment of such techniques in helicopter rotor flows unsatisfactory. In recent years, four major classes of numerical methods, including scale-resolving simulation (SRS) [1][2][3], high-order spatial discretization schemes [4][5][6][7], vorticity confinement (VC) method [8][9][10][11], and grid refinement techniques [12][13][14] have emerged to help improve the capability of preserving vortices in CFD simulations. Nevertheless, some of them are often prohibitive for industrial applications due to the substantial computational time and resources.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Vortex Feature-Based Vorticity Confinement Method Applied to Rotor Aerodynamics and Aeroacoustics

Vigevano

2023

Aerospace

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The accurate prediction of helicopter rotor aerodynamics and aeroacoustics using Computational Fluid Dynamics (CFD) techniques still remains a challenge, as the over-dissipation of numerical schemes results in a higher diffusive rate of rotor wake and vortices than what can be expected from the fluid governing equations. To alleviate this issue, a vortex feature-based vorticity confinement (FVC2-L2) method that combines the locally normalized λ2 vortex detection method with the standard second vorticity confinement (VC2) scheme is presented to counterbalance the truncation error introduced by the numerical discretization of the convective term while avoiding the over-confinement inside the boundary layer. The FVC2-L2 scheme is adopted for helicopter rotor aerodynamic and aeroacoustic predictions through its implementation in the multi-block structured grid CFD solver ROSITA and coupling with the aeroacoustic code ROCAAP based on the permeable surface Ffowcs Williams–Hawkings (PS-FWH) equation. This approach is assessed in helicopter rotor flows via three databases. Firstly, the well-documented HART-II rotor in the baseline condition is used to evaluate the capability of the presented VC scheme in blade–vortex interaction (BVI) phenomena prediction. Subsequently, the UH-1H non-lifting hovering rotor and the AH-1/OLS low-speed descending flight rotor are adopted for assessment of such a method in aeroacoustics. The benefits of the FVC2-L2 scheme in terms of aerodynamics prediction, wake preservation, and noise signal prediction are well demonstrated by comparison with the experimental data and the results obtained without VC schemes. Particularly, the FVC2-L2 scheme mainly improves the highly unsteady airloads prediction, and results in an improvement of BVI noise prediction by more than 5 dB with respect to the case without VC schemes for AH-1/OLS rotor case. Additionally, some shortcomings of the approach are noticed in engineering applications. On the basis of a simplified convective vortex, some provisional guidelines on the required εo value in terms of number of cells per vortex diameter are provided: an εo value ranging from 0.01 to 0.04 for grids which may represent the vortex core diameter with 6 to 12 cells.

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Section: Introductionmentioning

confidence: 99%

Assessment of the Vortex Feature-Based Vorticity Confinement Method Applied to Rotor Aerodynamics and Aeroacoustics

Vigevano

2023

Aerospace

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“…Accurately capturing the wake development and reaching a steady state of the forces on the rotor plane for hovering cases requires simulating many rotor rotations with a relatively small increment in time, making the overall process time consuming. Higher fidelity software typically use 3D URANS, although a higher fidelity rotorcraft aerodynamics has been reported using detached-eddy simulation (DES) where only three rotor revolutions were simulated because of CPU time limitations [5]. Unfortunately, this work reports no mesh nor timestep refinement study.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid Non-Linear Unsteady Vortex Lattice-Vortex Particle Method for Rotor Blades Aerodynamic Simulations

Proulx-Cabana

Nguyen

Prothin

et al. 2022

Fluids

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This study presents a hybrid non-linear unsteady vortex lattice method-vortex particle method (NL UVLM-VPM) to investigate the aerodynamics of rotor blades hovering in and out of ground effect. The method is of interest for the fast aerodynamic prediction of helicopter and smaller rotor blades. UVLM models the vorticity along the rotor blades and near field wakes with panels that are then converted into their equivalent vortex particle representations. The standard Vreman subgrid scale model is incorporated in the context of a large eddy simulation for mesh-free VPM to stabilize the wake development via particle strength exchange (PSE). The computation of the pairwise interactions in the VPM are accelerated using the fast-multipole method. Non-linear UVLM is achieved with a low computational cost viscous-inviscid alpha coupling algorithm through a stripwise 2D Reynolds-averaged Navier–Stokes (RANS) or empirical database. The aerodynamics of the scaled S76 rotor blades in and out of ground effect from the hover prediction workshop is investigated with the proposed algorithm. The results are validated with experimental data and various high-fidelity codes.

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“…Now, the URANS method is successfully used both for calculating single (Ignatkin and Konstantinov 2012;Garipova et al 2014;Ridhwan et al 2017;Abalkin et al 2020) and coaxial rotors (Deng et al 2019;Dacheng et al 2019;Kinzel et al 2019). Less often, the DES method is used (Dehaeze et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Coaxial Main Rotor Aerodynamics in the Hover with the Usage of Two Methods of Computational Fluid Dynamics

Konstantinov

Ignatkin

Makeev

et al. 2021

J. Aerosp. Technol. Manag.

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The paper is focused on numerical modeling of the aerodynamic characteristics of a full-scale coaxial main rotor in hover. The simulation was performed using two approaches of computational fluid dynamics (CFD): the original free wake model (FWM) developed by the authors and the unsteady Reynolds-averaged Navier-Stokes (URANS) equations method based on the Ansys Fluent software. The structure of the rotor vortex wake, flow images, vorticity and induced velocity fields, total and distributed aerodynamic characteristics of the rotor, including the rotor performance and figure of merit diagrams, have been analyzed. A comparison between FWM/URANS based calculations and calculated/experimental data by other authors has been performed. A satisfactory match of these data confirms reliability of used methods when modeling the aerodynamic characteristics of coaxial rotors. The FMW demonstrates a significant advantage in speed and resources intensity when calculating the total aerodynamic characteristics of a coaxial rotor. The URANS method makes it possible to model with significant accuracy the effects associated with the blade vortex interactions and pressure distribution over the blade surface. Finally, conclusions about most effectiveness of joint application of considered methods in solving complex problems of coaxial rotor aerodynamics has been made.

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Exploring the Detached-Eddy Simulation for Main Rotor Flows

Cited by 5 publications

References 18 publications

Assessment of the Vortex Feature-Based Vorticity Confinement Method Applied to Rotor Aerodynamics and Aeroacoustics

Assessment of the Vortex Feature-Based Vorticity Confinement Method Applied to Rotor Aerodynamics and Aeroacoustics

A Hybrid Non-Linear Unsteady Vortex Lattice-Vortex Particle Method for Rotor Blades Aerodynamic Simulations

Comparative Study of Coaxial Main Rotor Aerodynamics in the Hover with the Usage of Two Methods of Computational Fluid Dynamics

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