Accurate prediction of drag using Euler methods

Dam, C. P. van; Nikfetrat, Koorosh

doi:10.2514/3.46194

Cited by 42 publications

(19 citation statements)

References 5 publications

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“…Methods involving wake integration have been shown to be reasonably accurate at predicting profile and vortex drag. 6 ' 7 An equivalent lifting-line approach by Mathias et al 8 has also been shown to be able to accurately compute induced drag.…”

Section: Introductionmentioning

confidence: 99%

Wake Integration for Three-Dimensional Flowfield Computations: Applications

Hunt

Cummings

Giles

1999

Journal of Aircraft

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This paper examines the analytical, experimental, and computational aspects of the determination of the drag acting on an aircraft in flight, with or without powered engines, for subsonic/transonic flow. Using a momentum balance approach, the drag is represented by an integral over a crossflow plane at an arbitrary distance behind the aircraft. Asymptotic evaluation of the integral shows the drag can be decomposed into three components corresponding to streamwise vorticity and variations in entropy and stagnation enthalpy. These are related to the established engineering concepts of induced drag, wave drag, profile drag, and engine power and efficiency. This decomposition of the components of drag is useful in formulating techniques for accurately evaluating drag using computational fluid dynamics calculations or experimental data.

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Section: Introductionmentioning

confidence: 99%

Wake Integration for Three-Dimensional Flowfield Computations: Applications

Hunt

Cummings

Giles

1999

Journal of Aircraft

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“…A good survey of drag computations methods was recently prepared by Takahashi [16] and may be useful to future researchers in understanding the uses and limitations of the experimental approaches. Computational methods involving wake integration have been shown to be reasonably accurate at predicting profile and vortex drag, as shown by van Dam and Nikfetrat [20], Chatterjee and Janus [4], and Van Der Vooren and Sloof [21]. An equivalent lifting-line approach by Mathias et al [12] has also been shown to be able to accurately compute induced drag.…”

Section: Introductionmentioning

confidence: 90%

“…Euler computations were performed using the SAUNA CFD system [16,17]. This wing has been computationally studied by van Dam and Nikfetrat [20], and computations were performed to match those cases. Bounding boxes were used to decrease the size of the crossflow plane; a bounding box of N chords includes everything within a box outlined by -N < Y < +N and -N < Z < +N.…”

Section: Cutoff Formulation (Elliptic Wing Case)mentioning

confidence: 99%

Determination of drag from three-dimensional viscous and inviscid flowfield computations

Hunt

Cummings

Giles

1997

15th Applied Aerodynamics Conference

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A momentum balance approach is used to extract the drag from flowfield computations for wings and wing/bodies in subsonic/transonic flight. The drag is decomposed into vorticity, entropy, and enthalpy components which can be related to the established engineering concepts of induced drag, wave and profile drag, and engine power and efficiency. This decomposition of the drag is useful in formulating techniques for accurately evaluating drag using computational fluid dynamics calculations or experimental data. A formulation for reducing the size of the region of the crossflow plane required for calculating the drag is developed using cut-off parameters for viscosity and entropy. This improves the accuracy of the calculations and decreases the computation time required to obtain the drag results. The improved method is applied to a variety of wings, including the M6, W4, and Ml65 wings, Lockheed Wing A, a NACA 0016 wing, and an Elliptic wing. The accuracy of the resulting drag calculations is related to various computational aspects, including grid type (structured or unstructured), grid density, flow regime (subsonic or transonic), boundary conditions, and the level of the governing equations (Euler or Navier-Stokes). The results show that drag prediction to within engineering accuracy is possible using computational fluid dynamics, and that numerical drag optimization of complex aircraft configurations is possible.

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“…= total drag coef cient C Di = induced drag coef cient C Dv = viscous drag coef cient C Dw = wave drag coef cient C Fb = friction drag coef cient of fuselage C L = lift coef cient C p = pressure coef cient c = local chord N c = mean aerodynamic chord M = Mach number n = unit vector normal to ¾ or 6 Re = Reynolds number based on mean aerodynamic chord S = wing area T = temperature .u; v; w/ = Cartesian velocity components V = velocity .x; y; z/ = Cartesian coordinates, x along streamwise and z spanwise 1s D s ¡ s 1 = speci c entropy produced by shock (1u, 1v, 1w/ = nondimensional perturbation velocity components ½ = density 6 = transverse surface downstream at a distance where there is no streamwise pressure gradient ¾ = surface of shock wave Subscripts n = component normal to shock 1 = conditions just upstream of shock 1 = freestream conditions Introduction T HE assessment of aerodynamic performance is a very important and demandingtask in the design and developmentprocess of a civil aircraft. One of the most important parameters in the aerodynamic design process is the lift-to-drag ratio (L/D) in cruising ight condition, which governs the ef ciency of an aircraft.…”

Section: Dmentioning

confidence: 99%

Far-Field Drag-Prediction Technique Applied to Wing Design for Civil Aircraft

Qin

2003

Journal of Aircraft

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One of the emphases of this paper was the enhancement of drag prediction as well as the decomposition of drag into its physical components. The drag-prediction capability of the improved WBVS code for transonic ow about wing/body combinationwas veri ed by two approaches, code to code and code to experiment. The good agreements indicate that the wing body viscous has the capability to assess the aerodynamic performance in the supercritical wing design for civil transport aircraft. Another task of the present study was to redesign a supercritical wing for a new regional jet aircraft by employing the improved code as an analysis tool for wing/body combination. To accomplish this, a geometry-modifyingtechnique was employed to gradually improve the upper-and lower-surface shapes of wing sections. NomenclatureC D = total drag coef cient C Di = induced drag coef cient C Dv = viscous drag coef cient C Dw = wave drag coef cient C Fb = friction drag coef cient of fuselage C L = lift coef cient C p = pressure coef cient c = local chord N c = mean aerodynamic chord M = Mach number n = unit vector normal to ¾ or 6 Re = Reynolds number based on mean aerodynamic chord S = wing area T = temperature .u; v; w/ = Cartesian velocity components V = velocity .x; y; z/ = Cartesian coordinates, x along streamwise and z spanwise 1s D s ¡ s 1 = speci c entropy produced by shock (1u, 1v, 1w/ = nondimensional perturbation velocity components ½ = density 6 = transverse surface downstream at a distance where there is no streamwise pressure gradient ¾ = surface of shock wave Subscripts n = component normal to shock 1 = conditions just upstream of shock 1 = freestream conditions

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Accurate prediction of drag using Euler methods

Cited by 42 publications

References 5 publications

Wake Integration for Three-Dimensional Flowfield Computations: Applications

Wake Integration for Three-Dimensional Flowfield Computations: Applications

Determination of drag from three-dimensional viscous and inviscid flowfield computations

Far-Field Drag-Prediction Technique Applied to Wing Design for Civil Aircraft

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