Assessment of S-76 rotor hover performance in ground effect using an unstructured mixed mesh method

Hwang, Jisung; Kwon, Oh Joon

doi:10.1016/j.ast.2018.10.023

Cited by 25 publications

(3 citation statements)

References 8 publications

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“…The primary parameter through which ground effect impacts rotorcraft is rotor thrust, typically measured by the ratio of IGE to OGE rotor thrust. While extensive research has been conducted on the single-rotor ground effect, including model establishment [10,11], computational fluid dynamics simulations [12][13][14][15], and experimental flow visualization [16,17], which have validated the reliability of thrust ratio models [10], it is important to note that existing studies have shown limitations in directly applying single-rotor IGE models to multi-rotor aircraft [18,19]. This limitation presents challenges for the control of multi-rotor aircraft during takeoff, landing, and low-altitude flight.…”

Section: Introductionmentioning

confidence: 99%

Ground Effect on the Thrust Performance of Staggered Rotor System

Zhu,

Wei,

Nie

et al. 2024

Drones

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In this study, the thrust performance of a staggered rotor system in-ground effect (IGE) and out-of-ground effect (OGE) while considering the interaction on wake characteristics were investigated experimentally. A thorough comprehension of their performance holds significant importance for trajectory planning, aircraft design, landing safety, and energy-efficient landings. The complex interactions within staggered rotor systems and the impact of ground effects make rotor distance and ground interactions critical factors influencing near-ground flight performance. The study investigated the influence and enhancements of rotor thrust performance through an examination of rotor speed, lateral distance, and altitude. Experimental tests were conducted on two small-scale rotor models to assess the effects of these parameters. These experiments compared the performance of staggered rotor systems with isolated rotors, analyzing the competition mechanism between the thrust loss caused by interference and the thrust gain of rotors IGE. Furthermore, emphasis was placed on analyzing the thrust gain issues exhibited by staggered rotor systems under the condition of H = 2R. Additionally, the analysis was focused on identifying prominent relative positions for thrust performance and parameters for improving thrust performance in ground effects in staggered rotor systems.

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Section: Introductionmentioning

confidence: 99%

Ground Effect on the Thrust Performance of Staggered Rotor System

Zhu,

Wei,

Nie

et al. 2024

Drones

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“…The periodicity assumption was not presumed for the time-accurate simulation, thus, the four blades were resolved, and that increased the computational cost for the time-accurate method further. Hwang and Kwon 24 solved the same rotor case for different tip configurations with and without the ground effect at collective angle of 9° and M t of 0.65 using an in-house CFD code. The MRF approach was employed where the data exchange mechanism between the fixed and the rotating regions was accomplished using the overset method.…”

Section: Introductionmentioning

confidence: 99%

Development of a steady-state computational fluid dynamics solver for transonic rotorcraft flows

Abuhanieh

2024

Proceedings of the Institution of Mechanical Engineers, Part G:

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The capability for solving compressible fluid flows in the rotating frame of reference is added to an existed open-source CFD solver, namely, HiSA solver. The new implementation is explained and validated using the experimental data of the Sikorsky S-76 rotor. A comparison is presented between the moving mesh results obtained from the original HiSA code and the single rotating frame results achieved through the new implementation. The comparison includes an analysis of torque and thrust values, as well as computational costs. The results imply that, for evaluating the performance of an isolated rotor or for shape optimization purposes at the transonic regime, the single rotating frame method, like the one introduced in the current work, can provide accurate results within an acceptable computational budget. Furthermore, the results show that, at least 25 revolutions are required for the transient analysis to reach an acceptable steady-state converged solution like the one obtained by the single rotating frame method.

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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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Assessment of S-76 rotor hover performance in ground effect using an unstructured mixed mesh method

Cited by 25 publications

References 8 publications

Ground Effect on the Thrust Performance of Staggered Rotor System

Ground Effect on the Thrust Performance of Staggered Rotor System

Development of a steady-state computational fluid dynamics solver for transonic rotorcraft flows

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

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