Computation of circulation control airfoil flows

Swanson, R. C.; Rumsey, Christopher L.

doi:10.1016/j.compfluid.2009.05.002

Cited by 21 publications

(5 citation statements)

References 27 publications

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“…However, the SARC model yielded much better detailed agreement in terms of velocity and turbulence profiles over the Coanda surface compared to LES. Past studies (e.g., Swanson and Rumsey, 1 Pfingsten et al 7 ) have also shown the SARC model to be reasonably good for these types of flows. Yet, in spite of agreeing fairly well for many details of the flowfield over the Coanda surface, the best RANS models still produced larger airfoil circulation (higher lift) than LES, by between about 12 and 17%.…”

Section: Discussionmentioning

confidence: 99%

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

Rumsey

Nishino

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A numerical study over a nominally two-dimensional circulation control airfoil is performed using a largeeddy simulation code and two Reynolds-averaged Navier-Stokes codes. Different Coanda jet blowing conditions are investigated. In addition to investigating the influence of grid density, a comparison is made between incompressible and compressible flow solvers. The incompressible equations are found to yield negligible differences from the compressible equations up to at least a jet exit Mach number of 0.64. The effects of different turbulence models are also studied. Models that do not account for streamline curvature effects tend to predict jet separation from the Coanda surface too late, and can produce non-physical solutions at high blowing rates. Three different turbulence models that account for streamline curvature are compared with each other and with large eddy simulation solutions. All three models are found to predict the Coanda jet separation location reasonably well, but one of the models predicts specific flow field details near the Coanda surface prior to separation much better than the other two. All Reynolds-averaged Navier-Stokes computations produce higher circulation than large eddy simulation computations, with different stagnation point location and greater flow acceleration around the nose onto the upper surface. The precise reasons for the higher circulation are not clear, although it is not solely a function of predicting the jet separation location correctly.

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Section: Discussionmentioning

confidence: 99%

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

Rumsey

Nishino

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…Currently, those prediction tools are mostly based on Reynoldsaveraged Navier-Stokes (RANS) approaches because direct numerical simulations of the Navier-Stokes equations are infeasible for most practical applications. Earlier studies have shown that the separation location of the Coanda jet flow, which is critical to the performance of CC devices, is difficult to accurately predict using existing RANS models [3][4][5][6]. Several researchers, including the present authors, have recently been performing large-eddy simulations (LES) of flow around a basic CC airfoil model [7][8][9][10], which can provide comprehensive turbulence data for the Coanda flow (not easily obtainable from wind-tunnel tests) and thus contribute to the improvement of existing RANS models.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Wind-Tunnel Sidewall Effects on Circulation Control Airfoil Flows

Nishino

Shariff

2010

AIAA Journal

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Two-and three-dimensional numerical simulations are performed of the flow around a circulation control airfoil (using a Coanda jet blowing over a rounded trailing edge) placed in a rectangular wind-tunnel test section. The airfoil model spans the entire tunnel and the span-to-chord ratio of the model is 3.26. The objective of this numerical study, in which we solve the compressible Reynolds-averaged Navier-Stokes equations in a time-resolved manner (but the solutions eventually converge to steady states), is to investigate the physical mechanisms of wind-tunnel sidewall effects on the flow, especially in the midspan region. The three-dimensional simulations predict that the Coanda jet flow is quasi-two-dimensional until the flow separates from the trailing edge of the airfoil; however, the spanwise ends of this Coanda jet sheet then three-dimensionally roll up on the side walls of the wind tunnel to form two large streamwise vortices downstream. Careful comparisons between the two-and three-dimensional simulations reveal that the wind-tunnel stream goes below the airfoil more in the three-dimensional cases than in the two-dimensional cases due to the presence of these two streamwise vortices downstream. This results in smaller lift and larger drag being produced at the midspan of the airfoil in the three-dimensional cases than in the two-dimensional cases.

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“…The results reveal that, under different jet pressure ratios, the calculation results can basically capture the variation in pressure distribution on the Coanda surface, which coincides with the variation trend of the test results. According to other literature [8][9][10], different turbulence models cannot accurately capture the flow field characteristic details of the Coanda surface, and the calculation results of different turbulence models differ. When the jet pressure ratio is 5.6, the jet is still attached to the Coanda surface, and the calculated value of the pressure coefficient on the Coanda surface agrees well with the experimental value.…”

Section: Verification Of Calculation Accuracy Of Supersonic Coanda Jetmentioning

confidence: 99%

“…With the development of CFD technology, numerical calculation is an important development direction to predict the aerodynamic characteristics of CC airfoil. Swanson [8] and Rumsey calculated Novak's test model [6] based on the CFL3D program. The results reveal that a turbulence model with curvature correction can better solve the problem of high-speed fluid flowing around the Coanda surface, but the calculated lift coefficient is larger than the test result.…”

Section: Introductionmentioning

confidence: 99%

Flow Characteristics and Parameter Influence of the Under-Expansion Jet on Circulation Control Airfoil

Zhang

et al. 2023

Energies

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The enhancement in the jet pressure ratio and jet velocity contributes to expanding the control efficiency and control boundary of circulation control airfoil under high subsonic incoming flow. However, because of an excessive jet pressure ratio, the jet separates prematurely on the Coanda surface, resulting in control failure. In a bid to improve the adhesion capability of the jet under a high pressure ratio, a circulation control airfoil with a converging nozzle and back-facing step structure at the trailing edge was numerically simulated based on the Reynolds averaged Navier−Stokes equation (RANS), and a study was conducted on the complex flow structure of the under-expansion jet on the Coanda surface and the impact of design parameters such as jet pressure ratio, ellipticity, and nozzle height on the jet separation. The results show that the back-facing step provides an expansion space for the under-expansion jet and changes the shock-boundary layer interaction form. As the jet pressure ratio and nozzle height increase, the size of the shock cell increases, the strength of the intercepting shocks on both sides increases, and Mach reflection occurs, resulting in jet stratification and in a decline in the adhesion capability of the jet. The combination design of proper ellipticity and the back-facing step contributes to forming a closed low-pressure vortex area behind the step and promote jet attachment. Reducing the nozzle height can improve the adhesion capability of the jet under a high pressure ratio.

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Computation of circulation control airfoil flows

Cited by 21 publications

References 27 publications

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

Numerical Study of Wind-Tunnel Sidewall Effects on Circulation Control Airfoil Flows

Flow Characteristics and Parameter Influence of the Under-Expansion Jet on Circulation Control Airfoil

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