A Two-Equation Subgrid Model for Large-Eddy Simulation of High Reynolds Number Flows

Fang, Yichuan; Menon, Suresh

doi:10.2514/6.2006-116

Cited by 19 publications

(11 citation statements)

References 15 publications

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“…23) and the Georgia Tech LES-based model known as GIT-KES (Refs. 24,25). The S-A one-equation turbulence model is a RANS turbulence model, where the scales of the turbulence are statistically modeled for all length scales.…”

Section: Turbulence Simulationmentioning

confidence: 94%

Unsteady Aerodynamics of an Airfoil/Flap Combination on a Helicopter Rotor Using Computational Fluid Dynamics and Approximate Methods

Liu

Padthe²,

Friedmann³

et al. 2011

J Am Helicopter Soc

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The ability to model accurately and efficiently unsteady aerodynamic effects for actively controlled trailing-edge flaps (ACFs) is crucial for practical application of such systems for vibration and noise reduction as well as performance enhancement. Two-dimensional unsteady airloads due to oscillating flap motion are calculated and compared using various computational fluid dynamics (CFD) codes and a CFD-based reduced-order model (ROM). This ROM is based on the rational function approximations approach, which yields a state-space, time-domain aerodynamic model suitable for incorporation into comprehensive rotorcraft simulation codes. The accuracy of this model is demonstrated across a practical range of unsteady flow conditions encountered by active flaps. TwoReynolds-averaged Navier-Stokes solvers (CFD++ and OVERFLOW) are employed in conjunction with various turbulence models, including large eddy simulation based models, so as to examine code independence. Flow physics associated with three-dimensional effects, flap hinge gap, as well as compressibility effects are also examined. Nomenclature

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Section: Turbulence Simulationmentioning

confidence: 94%

Unsteady Aerodynamics of an Airfoil/Flap Combination on a Helicopter Rotor Using Computational Fluid Dynamics and Approximate Methods

Liu

Padthe²,

Friedmann³

et al. 2011

J Am Helicopter Soc

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“…This method includes third-order MUSCL for cell-interface reconstruction, Roe's flux-difference-splitting scheme [7] for the inviscid flux computation, second-order central difference for viscous flux, and first-order implicit scheme for time-marching. A two-equation kinetic eddy simulation turbulence model [8] was used for estimating the eddy viscosity. The code has been parallelized using messagepassing interface libraries for improved throughput.…”

Section: Methodsmentioning

confidence: 99%

Hybrid Navier-Stokes/Free-Wake Method for Modeling Blade-Vortex Interactions

Min

Sankar

2010

Journal of Aircraft

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Techniques for accurate capturing of rotor blade-vortex-interaction phenomena are discussed. A number of algorithmic enhancements have been systematically examined, including geometric conservation law, refined metric and Jacobian computations, higher-order spatial and second-order temporal accuracy schemes, and embedded grids. The use of the geometric conservation law and refined metric computation were found to reduce nonphysical mass accumulation errors. These enhancements improve stability and accuracy of the higher-order schemes near far-field boundaries and in the vicinity of highly skewed cells. Embedded grids with an increased grid density were found to improve the predictions. It was also observed that the free-wake model (and, in particular, the determination of the trailing tip-vortex release point) plays a critical role in the blade-vortex-interaction prediction.= conservative variables vector, vortex identifier variable q = flow properties R = blade radius r = blade radial location t = nondimensionalized time -V = cell volume w = weight factor , , = curvilinear coordinates = azimuth angle

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“…Turbulence closure was achieved by two-equation kinetic eddy simulation (KES) (Ref. 24). Figure 10 shows the computational grid consisting of the duct and bell-mouth domains.…”

Section: Three-dimensional Full Cfdmentioning

confidence: 99%

Experimental and Numerical Study of Internal Flow through a Rotating Duct

Karpatne¹,

Sirohi²,

Min³

et al. 2017

j am helicopter soc

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Several rotorcraft applications such as circulation control and tip jet-driven rotors involve internal spanwise flow along a ducted rotor blade. The primary goal of this work was to study a self-pumping pneumatically driven duct flow by both generating a quasi one-dimensional model for such flows and providing a validation data set for rotorcraft applications. The flow behavior inside a 1.32-m-long cylindrical duct, with a duct cross-sectional diameter of 52 mm, and rotating at speeds up to 1050 RPM was studied. Spanwise pressure distribution, duct velocity, hub forces, and moments from the numerical model showed good correlation with experiments. A considerable internal mass flow rate (∼0.3 kg/s) was also observed for a steadily rotating duct. In the presence of a time-varying valve at the inlet, transient spanwise pressure variations showed periodic fluctuations in pressure that diminished once the valve was fully open. The experimental results were compared with results of two computational models-a quasi one-dimensional finite volume Euler equation solver and a full threedimensional computational fluid dynamics solver. The ability to model a range of boundary conditions, time-varying duct cross-sectional area to simulate a flow control valve, frictional losses, duct sweep, and centrifugal as well as Coriolis effects on the flow is included. The experiments revealed key information about pressure at the duct's outlet. It was observed that when the duct's inlet is closed, the duct's outlet pressure is less than its ambient value. The knowledge of these boundary conditions is key in modeling flow through rotating ducts. Nomenclature Kthermal conductivity of the medium, W/m·K P local static pressure, Pa P atm static pressure at ambient conditions, Pa T atm static air temperature at ambient conditions, K u velocity of fluid in the x-direction, m/s v velocity of the fluid in the y-direction, m/s x coordinate along duct axis, m y coordinate perpendicular to duct axis, m ρ density of air, kg/m 3 ρ atm density of air at ambient conditions, kg/m 3 rotational rate of the duct, rad/s

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A Two-Equation Subgrid Model for Large-Eddy Simulation of High Reynolds Number Flows

Cited by 19 publications

References 15 publications

Unsteady Aerodynamics of an Airfoil/Flap Combination on a Helicopter Rotor Using Computational Fluid Dynamics and Approximate Methods

Unsteady Aerodynamics of an Airfoil/Flap Combination on a Helicopter Rotor Using Computational Fluid Dynamics and Approximate Methods

Hybrid Navier-Stokes/Free-Wake Method for Modeling Blade-Vortex Interactions

Experimental and Numerical Study of Internal Flow through a Rotating Duct

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