An experimental investigation of flowfield about a multielement airfoil

Nakayama, A.; Kreplin, H.-P.; Morgan, H. L.

doi:10.2514/6.1988-2035

Cited by 8 publications

(24 citation statements)

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“…Wake bursting occurs as a result of high velocity deficit gathered by the wakes under adverse pressure gradients, and hence the term wake deceleration has been interchangeably used with wake bursting in this study. 6 American Institute of Aeronautics and Astronautics Gap size l s,x 0.211 in.…”

Section: Resultsmentioning

confidence: 99%

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Bansal

Selig

2016

34th AIAA Applied Aerodynamics Conference

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The importance of aerodynamic downforce in competitive motorsports has been well established. Much of this aerodynamic downforce is produced from the inverted multielement wings at the front and the rear of the car. While such a high-lift system is capable of producing high downforce as a result of the interaction between flows around adjacent elements, there may exist off-the-surface flow reversal, commonly known as wake bursting, causing an adverse effect on the downforce generated. Since the phenomenon of off-the-surface flow reversal occurs as a result of retardation of a wake under adverse pressure gradients, wake bursting is also referred to as wake deceleration in this study. A steady-state two-dimensional CFD analysis of a racecar multielement airfoil was carried out to study wake deceleration characteristics in ground effect. Simulations were performed using ANSYS Fluent TM , which is a finite-volume method (FVM) based commercial hybridgrid Reynolds-averaged Navier-Stokes (RANS) equations solver. Computational results were obtained using a two equation shear stress transport (SST) k-ω model coupled with a one equation intermittency transition model to predict the laminar-to-turbulent boundary layer transition. Effects of ground clearance height on the main element decelerated wake were analyzed. Effects of varying flap ratio, flap deflection, angle of attack, and gap sizes on the wake deceleration patterns have been investigated. It was found that decreasing the ground clearance led to a significant increase in the amount of the main element wake bursting. Increased wake bursting at higher angles of attack was found to have caused a drop in downforce without any surface-flow separation. Although the main element wake was strongly affected while varying each of these parameters, the size of the flap wake was not affected significantly. Nomenclature c = system chord length c 1 = main element chord length c 2 = flap chord length C d = two-dimensional drag coefficient C l = two-dimensional downforce coefficient h = ground clearance height l s,x = overhang distance l s,y = gap size M ∞ = freestream Mach number N = total number of cells in the grid p ∞ = freestream static pressure Re = Reynolds number based on system chord length Re θ = transition momentum thickness Reynolds number T ∞ = freestream static temperature u = velocity component in x-direction v = velocity component in y-direction α = angle of attack δ f = flap deflection angle γ = intermittency ρ = density of air

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Section: Resultsmentioning

confidence: 99%

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Bansal

Selig

2016

34th AIAA Applied Aerodynamics Conference

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“…However, computational codes such as the one reported by Stevens [3], required flow field static pressures for their evaluation. Such pressure data were reported by Adair and Clifton [4], Nakayama and Kreplin [5] and Wentz and Ostawari [6], but they measured these pressures at single points and did not include separated flow at stall conditions. Therefore, there was a need to provide a new method of measuring pressures for validating computational codes developed for separated flows over airfoils, as in Ref [7].…”

Section: Introduction mentioning

confidence: 89%

Design and Application of a New Splitter Plate Pressure Probe for Wind Tunnel Flow Measurements

Biber¹

2019

JMEA

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A new siplitter plate presure probe was developed for flow field measurements on an airfoil with slotted flap in a low speed wind tunnel with 7 by 10 ft test section. Wind tunnel tests were conducted at a Reynolds number of 2.2 million and Mach number of 0.13. The splitter plate was made of aluminum and had pressure taps on its one side. The probe can make many measurements in the plane of the plate simultaneously by using these pressure tabs. It was supported by a traversing strut in the wind tunnel and surveyed the flow field on the airfoil upper surface. Measured pressures were presented by isobars of coefficients. These isobars were connected with the pressure coefficients distributed over the airfoil. Results of splitter plate pressure probe compare well with other single-point measuring probes. However, results show that no matter how small the probe, its presence in the flow causes a disturbance, especially in the highly time-dependent separated flow regions.

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“…The ow was considered to be two-dimensional if the magnitude of the spanwise nonuniformity was less than 5 percent of the total C p variation over the entire model. 10 The data presented are uncorrected for boundary e ects were taken at a Reynolds Re number of 1 10 6 based on the nested chord.…”

Section: Experimental Testing Methodsmentioning

confidence: 99%

A surrogate approach to the experimental optimization of multielement airfoils

John

Landman

1996

6th Symposium on Multidisciplinary Analysis and Optimization

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The incorporation of experimental test data into the optimization process is accomplished through the use of Bayesian-validated surrogates. In the surrogate approach, a surrogate for the experiment (e.g., a response surface) serves in the optimization process. The validation step of the framework provides a qualitative assessment of the surrogate quality, and bounds the surrogate-for-experiment error on designs \near" surrogate-predicted optimal designs. The utility of the framework is demonstrated through its application to the experimental selection of the trailing edge ap position to achieve a design lift coe cient for a three-element airfoil.

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An experimental investigation of flowfield about a multielement airfoil

Cited by 8 publications

References 0 publications

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Wake Deceleration of a Racecar Multielement Airfoil in Ground Effect

Design and Application of a New Splitter Plate Pressure Probe for Wind Tunnel Flow Measurements

A surrogate approach to the experimental optimization of multielement airfoils

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