Revising of the Near Ground Helicopter Hover: The Effect of Ground Boundary Layer Development

Andronikos, Theologos; Papadakis, G.; Riziotis, Vasilis A.; Voutsinas, Spyros G.

doi:10.3390/app11219935

Cited by 4 publications

(1 citation statement)

References 22 publications

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“…Furthermore, viscous effects are important when studying the rotor wake interaction with the boundary layer developed on surrounding bodies (e.g., helicopter obstacle [9] or WT tower) or even the ground. Such interactions affect the rotor performance and the loading of the rotor [10,11]. Another possible aspect where CFD analysis may be needed is the rotor operation close to bluff bodies with a non-thin boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Level of Fidelity of an Actuator Line Model in Predicting Loads and Deflections of Rotating Blades under Uniform Free-Stream Flow

et al. 2021

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In this paper, the accuracy of an in-house Actuator Line (AL) model is tested on aeroelastic simulations of a Wind Turbine (WT) rotor and a helicopter Main Rotor (MR) under uniform free-stream flow. For the scope of aeroelastic analyses, the AL model is coupled with an in-house multibody dynamics code in which the blades are modeled as beams. The advantage from the introduction of CFD analysis in rotorcraft aeroelasticity is related to its capability to account in detail for the interaction of the rotor wake with the boundary layer developed on the surrounding bodies. This has proven to be of great importance in order to accurately estimate the aerodynamic forces and thus the corresponding structural loads and deflections of the blades. In wind turbine applications, a good example of the above is the rotor/ground interaction. In helicopter configurations, the interaction of MR with the ground or the fuselage and the interaction of tail rotor with the duct in fenestron configurations are typical examples. Furthermore, CFD aerodynamic analysis is an obvious modeling option in which the above mentioned asset can be combined with the consideration of the mutual interaction of the rotor with the ambient turbulence. A WT rotor operating inside the atmospheric boundary layer under turbulent free-stream flow is such a case. In the paper, AL results are compared against Blade Element Momentum (BEM) and Lifting Line (LL) model results in the case of the WT, whereas LL and measured data are considered in the helicopter cases. Blade loads and deflections are mainly compared as azimuthal variations. In the helicopter MR cases, where comparison is made against experimental data, harmonic analysis of structural loads is shown as well. Overall, AL proves to be as reliable as LL in the canonical cases addressed in this paper in terms of loads and deflections predictions. Therefore, it can be trusted in more complex flow conditions where viscous effects are pronounced.

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Section: Introductionmentioning

confidence: 99%

Investigating the Level of Fidelity of an Actuator Line Model in Predicting Loads and Deflections of Rotating Blades under Uniform Free-Stream Flow

et al. 2021

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A Cartesian Immersed Boundary Method Based on 1D Flow Reconstructions for High-Fidelity Simulations of Incompressible Turbulent Flows Around Moving Objects

Giannenas

Bempedelis

Schuch

et al. 2022

Flow Turbulence Combust

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The aim of the present numerical study is to show that the recently developed Alternating Direction Reconstruction Immersed Boundary Method (ADR-IBM) (Giannenas and Laizet in Appl Math Model 99:606–627, 2021) can be used for Fluid–Structure Interaction (FSI) problems and can be combined with an Actuator Line Model (ALM) and a Computer-Aided Design (CAD) interface for high-fidelity simulations of fluid flow problems with rotors and geometrically complex immersed objects. The method relies on 1D cubic spline interpolations to reconstruct an artificial flow field inside the immersed object while imposing the appropriate boundary conditions on the boundaries of the object. The new capabilities of the method are demonstrated with the following flow configurations: a turbulent channel flow with the wall modelled as an immersed boundary, Vortex Induced Vibrations (VIVs) of one-degree-of-freedom (2D) and two-degree-of-freedom (3D) cylinders, a helicopter rotor and a multi-rotor unmanned aerial vehicle in hover and forward motion. These simulations are performed with the high-order fluid flow solver which is based on a 2D domain decomposition in order to exploit modern CPU-based supercomputers. It is shown that the ADR-IBM can be used for the study of FSI problems and for high-fidelity simulations of incompressible turbulent flows around moving complex objects with rotors.

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Stable hovering of proximity quadrotor UAV in-ground effect via model compensation controller

Li,

Qi,

Wang

et al. 2024

Nonlinear Dyn

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Revising of the Near Ground Helicopter Hover: The Effect of Ground Boundary Layer Development

Cited by 4 publications

References 22 publications

Investigating the Level of Fidelity of an Actuator Line Model in Predicting Loads and Deflections of Rotating Blades under Uniform Free-Stream Flow

Investigating the Level of Fidelity of an Actuator Line Model in Predicting Loads and Deflections of Rotating Blades under Uniform Free-Stream Flow

A Cartesian Immersed Boundary Method Based on 1D Flow Reconstructions for High-Fidelity Simulations of Incompressible Turbulent Flows Around Moving Objects

Stable hovering of proximity quadrotor UAV in-ground effect via model compensation controller

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