Investigation of confluent boundary layers in high-lift flows

Ying, Susan X.; Spaid, Frank W.; McGinley, Catherine B.; Rumsey, Christopher L.

doi:10.2514/6.1998-2622

Cited by 13 publications

(7 citation statements)

References 12 publications

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“…In light of this, the time-accurate solutions suggest that the non-realistic variation in pressure seen in the steady-state calculations is partially the result of using a variable timestep (constant CFL number). Similar phenomenon have been observed in calculations with separated flow on multi-element airfoil calculations at high lift 13 , and in calculations of a lobed nozzle with a large separated base region 14 .…”

Section: Mach 09 Nprsupporting

confidence: 56%

Computational Study of Axisymmetric Off-Design Nozzle Flows

DalBello

Georgiadis

Yoder

et al. 2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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Section: Mach 09 Nprsupporting

confidence: 56%

Computational Study of Axisymmetric Off-Design Nozzle Flows

DalBello

Georgiadis

Yoder

et al. 2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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“…In Ref. 20 approach was required to obtain converged solutions for calculation of a multi-element airfoil exhibiting large-scale separation at high angles of attack. In Ref.…”

Section: A Mach 030 Nozzle Flowmentioning

confidence: 99%

Turbulence Modeling Effects on Calculation of Lobed Nozzle Flowfields

Georgiadis

Rumsey

Yoder

et al. 2006

Journal of Propulsion and Power

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Two Reynolds-averaged Navier-Stokes solvers, CFL3D and WIND, are applied to the subsonic turbulent jet flowfield originating from a six-lobed nozzle, with emphasis placed on turbulence modeling effects. The turbulence models investigated include linear one-equation and two-equation models and nonlinear two-equation explicit algebraic stress model (EASM) formulations. Two nozzle operating points are investigated, corresponding to exit Mach numbers of 0.30 and 0.94. Comparisons of calculated mean axial velocities and turbulence intensities are made with experimental data. All of the turbulence models were deficient in predicting the initial mixing rate exhibited by the experimental data. The one-equation model provided the best agreement with experimental data in the near field of the jet. The linear two-equation models and a modified EASM provided better agreement with data in the farfield. The Mach 0.30 k-ω EASM calculation required a time-accurate calculation because of significant unsteadiness in the initial jet region, which is believed to be characteristic of the nozzle flow under consideration. Nomenclature D= equivalent jet diameter k = turbulent kinetic energy P = turbulent production P T = stagnation pressure P ∞ = ambient static pressure S i j = rate of strain tensor t = time U jet = jet-exit velocity u = velocity u = fluctuating velocity W i j = vorticity tensor x, y, z = Cartesian coordinates y + = wall-normal coordinate = turbulent dissipation rate κ = von Kármán constant ν = kinematic viscosity ν t = kinematic eddy viscosity ρ = density τ = turbulent timescale τ i j = turbulent stress tensor ω = specific turbulent dissipation rate

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“…The flow over an airfoil is inherently complex and exhibits a variety of physical phenomena including strong pressure gradients, flow separation, and confluence of boundary layers and wakes [e.g., Khorrami et al (1999Khorrami et al ( , 2000, Ying et al (1998), Mathias et al (1999)]. The complex unsteady flow is difficult to compute by traditional computational fluid dynamics (CFD) techniques based on Reynolds-averaged Navier-Stokes (RANS) equations (Rumsey and Ying, 2002).…”

Section: Introductionmentioning

confidence: 99%

Active control of flow separation over an airfoil using synthetic jets

You¹,

Moin²

2008

Journal of Fluids and Structures

185

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We perform large-eddy simulation of turbulent flow separation over an airfoil and evaluate the effectiveness of synthetic jets as a separation control technique. The flow configuration consists of flow over an NACA 0015 airfoil at Reynolds number of 896,000 based on the airfoil chord length and freestream velocity. A small slot across the entire span connected to a cavity inside the airfoil is employed to produce oscillatory synthetic jets. Detailed flow structures inside the synthetic-jet actuator and the synthetic-jet/cross-flow interaction are simulated using an unstructured-grid finite-volume large-eddy simulation solver. Simulation results are compared with the 2005 experimental data of Gilarranz et al., and qualitative and quantitative agreements are obtained for both uncontrolled and controlled cases. As in the experiment, the present large-eddy simulation confirms that synthetic-jet actuation effectively delays the onset of flow separation and causes a significant increase in the lift coefficient. Modification of the blade boundary layer due to oscillatory blowing and suction and its role in separation control is discussed. r

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Investigation of confluent boundary layers in high-lift flows

Cited by 13 publications

References 12 publications

Computational Study of Axisymmetric Off-Design Nozzle Flows

Computational Study of Axisymmetric Off-Design Nozzle Flows

Turbulence Modeling Effects on Calculation of Lobed Nozzle Flowfields

Active control of flow separation over an airfoil using synthetic jets

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