Shaping of airplane fuselages for minimum drag

Dodbele, S. S.; Dam, C. P. van; Vijgen, P. M. H. W.; Holmes, Bruce J.

doi:10.2514/3.45444

Cited by 39 publications

(16 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The theoretical drag on different bodies of revolution calculated in Parsons et al, [8], Dodbele et al, [9], Zedan et al [10], and Lutz & Wagner [11] are rather different and significantly exceed the estimation (1). For example, in [10] In the case of the attached flow pattern, slender bodies of revolution can delay laminarturbulent transitions on their surfaces and reduce the skin-friction drag.…”

Section: Introductionmentioning

confidence: 86%

Testing a Special Shaped Body of Revolution Similar to Dolphins Trunk

Nesteruk¹,

Brühl²,

Moeller³

2018

Nauk. Visti KPI

View full text Add to dashboard Cite

Background. The high swimming velocities of some aquatic animals such as dolphins continue to attract great interest of researchers. The friction drag of the dolphin, estimated with the use of turbulent friction coefficient of the flat plate, was so high to declare that the dolphin should not be able to swim as fast as it does with the muscle power it possesses. Some previous tests of the rigid bodies, similar to the animal shapes, and gliding dolphins revealed the attached flow patterns. Nevertheless, the researchers connected with industrial applications believe that separation is inevitable on every smooth shape, provided no active boundary-layer control methods (e.g., suction) are applied. Objective. The aim of the paper is to test a special shaped rigid body of revolution in the wind tunnel in order to show that the boundary-layer separation can be removed without any active flow control methods. Methods. Wind tunnel tests were carried out at velocities 15, 35, and 55 m/s. Static pressure measurements and the oil-flow visualization were used. For this study, we take the UA-2 special shaped model of 200 mm length and 56.78 mm of the maximum diameter. The closed version of the UA-2c model is similar to the dolphin body. The tests were carried out in the subsonic wind tunnel MUB of the Institut für Strömungsmechanik (ISM) at Technische Universität Braunschweig, Germany. The wind tunnel MUB of ISM is an actively cooled Goettingen type tunnel with a square section of 1.3 m and the turbulence level of about 0.2 %. The technique of oil-flow visualization was used to deliver information of the surface near flow. The color used is a mixture of thin mineral oil and petrol, in an optimized ratio. The very fine titan-dioxide particles and UV-light reactive polymer particles in the color deliver a high contrast picture of the flow directions with a high spatial resolution. Results. The distribution of the static pressure and the oil-flow visualization are presented at three angles of attack. The flow pattern at zero angle of attack is probably attached and laminar. Conclusions. Pressure measurements and the flow visualization on the special shaped body of revolution showed that it is probably possible to avoid separation in rather large range of the Reynolds numbers. Further experiments are necessary with the use of a visualization of the flow volume and hot-wire velocity probes to clarify the behavior of the boundary layer, its separation and laminar-to-turbulent transition characteristics.

show abstract

Section: Introductionmentioning

confidence: 86%

Testing a Special Shaped Body of Revolution Similar to Dolphins Trunk

Nesteruk¹,

Brühl²,

Moeller³

2018

Nauk. Visti KPI

View full text Add to dashboard Cite

show abstract

“…In most cases, aerostat envelopes can be assumed to be axi-symmetric bodies of revolution. Many studies, both experimental [1][2][3] , and computational [4][5][6][7][8][9] for obtaining low drag shapes of such bodies for various applications and Reynolds number regimes have been reported in literature. One of the most important considerations in interpreting the results of these studies is the characteristic length that is used to define the Reynolds number of the envelope.…”

Section: Drag Minimization Of Axi-symmetric Bodiesmentioning

confidence: 99%

A generic methodology for determination of drag coefficient of an aerostat envelope using CFD

Kale¹,

Joshi²,

Pant³

2005

AIAA 5th ATIO And16th Lighter-Than-Air Sys Tech. And Balloon Systems Conferences

View full text Add to dashboard Cite

Aerostat envelopes are generally bodies of revolution with length to diameter ratio ranging from 3 to 5. Drag coefficient for this class of bodies can be obtained using empirical formulae or co-relations based on experimental studies. However such formulae are valid for specific class of envelope shapes only and result in errors of around 30% compared to the values determined by numerical methods. The motivation for the present study arose from the need for a simple but generic methodology to estimate coefficient of drag as a function of envelope geometry, thus eliminating the need for running numerically expensive CFD codes each time the shape is altered during an optimisation exercise. In a previous study, the envelop shape was parameterized in terms of six geometric coefficients, and a shape generation algorithm was developed to generate various possible shapes satisfying manufacturing and few geometric design constraints. An empirical co-relation for envelope drag coefficient was developed, but it was not amenable to coupling with an MDO process, since it required detailed geometric data about the envelope shape, especially the coordinates of several points at the nose and trailing edge, and the grid density in these regions. In the present study, around 600 feasible shapes satisfying the user-specified volume and length constraints were generated using the shape generation algorithm. The flow patterns over these shapes were studied using FLUENT TM CFD Package and a better corelation was obtained by fitting a quadratic response surface using Design-Expert TM package. The current methodology uses only the values of six design variables to determine the drag coefficient, thus making it easy to integrate with a multidisciplinary optimization algorithm for determining optimum envelope shape.

show abstract

“…8. For the present application, this computational approach has been modified to include compressibility effects.…”

Section: Compressible Boundary-layer Stability Computationmentioning

confidence: 99%

“…8 An improved turbulent boundary-layer calculation method is incorporated in the panel method to give more realistic drag correlations with available experimental data. The turbulent boundary-layer calculations are based on Head's entrainment method as modified by Shanebrook and Sumner.…”

Section: Drag Reduction Due To Compressibility Effectmentioning

confidence: 99%

“…Also, Hertel based his innovative extrapolation from fish-body shapes to transport fuselage shapes on integral boundary-layer transition criteria, which have been found to be unreliable for axisymmetric body shapes at higher length-Reynolds numbers. 8 The drag-reduction potential of laminar hydrodynamic bodies was recognized earlier by Carmichael, 9 ' 10 who designed low fineness-ratio axisymmetric bodies that were successfully tested underwater, achieving transition-length Reynolds numbers as high as 18 x 10 6 at R L = 38 x 10 6 . 11 These promising experimental results paved the way for numerical optimization studies by Parsons et al, 12 Dalton and Zedan, 13 Pinebrook and Dalton, 14 and Dodbele et al 8 ' 15 All of these studies investigated the effect of body shape on the viscous drag of axisymmetric bodies for incompressible flow conditions.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Effects of compressibility on design of subsonic fuselages for natural laminar flow

Vijgen

Dodbele

Holmes

et al. 1988

Journal of Aircraft

View full text Add to dashboard Cite

At high subsonic speeds, density gradients in compressible laminar boundary layers provide increased damping of the two-dimensional and axisymmetric Tollmien-Schlichting instability waves. The favorable influence of flow compressibility provides a unique opportunity to attain natural laminar flow over portions of high-speed subsonic fuselages for drag-reduction purposes. For bodies of moderate fineness ratios (e.g., 5 to 9), the generally destabilizing effect of increasing length-Reynolds number on laminar stability is overpowered by the damping effect of compressibility. Compressible linear stability analyses (based on the e n method) are presented for the laminar boundary layer on axisymmetric body shapes for length-Reynolds numbers up to 86.6 million and Mach numbers up to 0.80. At a fixed Reynolds number, based on body length, it is predicted that the transition-length Reynolds number triples as the Mach number increases from near zero to 0.80. The favorable effects of flow compressibility on laminar stability might be exploited in the design of external fuel tanks, engine nacelles, and fuselages of business or commuter transports. Attainment of natural laminar flow on the forebodies of larger transport fuselages could provide significant reductions in total drag of transport aircraft. NomenclatureA/A 0 = ratio of local disturbance amplitude to amplitude at point of neutral stability for fixed disturbance frequency C D = body drag coefficient (based on frontal area) C Dref = drag coefficient for boundary-layer transition location fixed at x/L = 0.05 at given Mach numberfineness ratio (body length/maximum body diameter) L = body length, ft M = local surface Mach number MO,, = freestream Mach number n = logarithmic exponent of amplitude-growth ratio of unstable Tollmien-Schlichting wave, n = &i(A/A 0 ) R L = Reynolds number based on freestream conditions and body length R TR = Reynolds number based on freestream conditions and transition length T.S. = Tollmien-Schlichting x = axial coordinate starting at nose, ft

show abstract

Shaping of airplane fuselages for minimum drag

Cited by 39 publications

References 12 publications

Testing a Special Shaped Body of Revolution Similar to Dolphins Trunk

Testing a Special Shaped Body of Revolution Similar to Dolphins Trunk

A generic methodology for determination of drag coefficient of an aerostat envelope using CFD

Effects of compressibility on design of subsonic fuselages for natural laminar flow

Contact Info

Product

Resources

About