Measurements in three-dimensional turbulent boundary layer on a yawed flat plate induced by leading edge vortex

2008 ◽  
pp. 217-221
Author(s):  
N. V. Chandrasekhara Swamy ◽  
B. H. Lakshmana Gowda ◽  
V. R. Lakshminatfi
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Three Dimensional ◽  
Leading Edge ◽  
Leading Edge Vortex ◽  
Edge Vortex

3D Effects in the Wake Vortex Formation of an Elliptic Flat Plate in Hover

2017 ◽  
Author(s):  
Vivek Nair ◽  
Siddarth Chintamani ◽  
B. H. Dennis
Keyword(s):  
Flat Plate ◽  
Vortex Formation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Leading Edge Vortex ◽  
Elliptic Geometry ◽  
3D Effects ◽  
Edge Vortex ◽  
Formation Number ◽  
Vorticity Transport

A Numerical Analysis is conducted to investigate the Leading Edge Vortex (LEV) dynamics of an elliptic flat plate undergoing 2 dimensional symmetric flapping motion in hover. The plate is modeled with an aspect ratio of 3 and a flapping trajectory resulting in Reynolds number 225 is studied. The leading edge vortex stability is analyzed as a function of the non dimensional formation number and a vorticity transport analysis is carried to understand the flux budgets present. The LEV formation number is found to be 2.6. The results of vorticity analysis show the highly three dimensional nature of the LEV growth for an elliptic geometry.

scholarly journals The leading-edge vortex on a rotating wing changes markedly beyond a certain central body size

2018 ◽  
Vol 5 (7) ◽  
pp. 172197 ◽  
Author(s):  
Shantanu S. Bhat ◽  
Jisheng Zhao ◽  
John Sheridan ◽  
Kerry Hourigan ◽  
Mark C. Thompson
Keyword(s):  
Reynolds Number ◽  
Body Size ◽  
Central Body ◽  
Three Dimensional ◽  
Leading Edge ◽  
Particle Image Velocimetry Technique ◽  
Leading Edge Vortex ◽  
Rapid Acquisition ◽  
Edge Vortex ◽  
Rotating Wing

Stable attachment of a leading-edge vortex (LEV) plays a key role in generating the high lift on rotating wings with a central body. The central body size can affect the LEV structure broadly in two ways. First, an overall change in the size changes the Reynolds number, which is known to have an influence on the LEV structure. Second, it may affect the Coriolis acceleration acting across the wing, depending on the wing-offset from the axis of rotation. To investigate this, the effects of Reynolds number and the wing-offset are independently studied for a rotating wing. The three-dimensional LEV structure is mapped using a scanning particle image velocimetry technique. The rapid acquisition of images and their correlation are carefully validated. The results presented in this paper show that the LEV structure changes mainly with the Reynolds number. The LEV-split is found to be only minimally affected by changing the central body radius in the range of small offsets, which interestingly includes the range for most insects. However, beyond this small offset range, the LEV-split is found to change dramatically.

Three-Dimensional Solution of Flows over Wings with Leading-Edge Vortex Separation

AIAA Journal ◽  
1976 ◽  
Vol 14 (4) ◽  
pp. 519-525 ◽  
Author(s):  
James A. Weber ◽  
Guenter W. Brune ◽  
Forrester T. Johnson ◽  
Paul Lu ◽  
Paul E. Rubbert
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Dimensional Solution ◽  
Leading Edge Vortex ◽  
Vortex Separation ◽  
Edge Vortex

Parameter Variation and the Leading-Edge Vortex of a Rotating Flat Plate

AIAA Journal ◽  
2014 ◽  
Vol 52 (2) ◽  
pp. 348-357 ◽  
Author(s):  
Craig J. Wojcik ◽  
James H. J. Buchholz
Keyword(s):  
Flat Plate ◽  
Leading Edge ◽  
Parameter Variation ◽  
Leading Edge Vortex ◽  
Edge Vortex

Simulation of blunt-fin-induced shock-wave and turbulent boundary-layer interaction

1985 ◽  
Vol 154 ◽  
pp. 163-185 ◽  
Author(s):  
Ching-Mao Hung ◽  
Pieter G. Buning
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Flat Plate ◽  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Layer Interaction ◽  
Boundary Layer Interaction

The Reynolds-averaged Navier–Stokes equations are solved numerically for supersonic flow over a blunt fin mounted on a flat plate. The fin shock causes the boundary layer to separate, which results in a complicated, three-dimensional shock-wave and boundary-layer interaction. The computed results are in good agreement with the mean static pressure measured on the fin and the flat plate. The main features, such as peak pressure on the fin leading edge and a double peak on the plate, are predicted well. The role of the horseshoe vortex is discussed. This vortex leads to the development of high-speed flow and, hence, low-pressure regions on the fin and the plate. Different thicknesses of the incoming boundary layer have been studied. Varying the thicknesses by an order of magnitude shows that the size of the horseshoe vortex and, therefore, the spatial extent of the interaction are dominated by inviscid flow and only weakly dependent on the Reynolds number. Coloured graphics are used to show details of the interaction flow field.

Receptivity to free-stream vorticity of flow past a flat plate with elliptic leading edge

2010 ◽  
Vol 653 ◽  
pp. 245-271 ◽  
Author(s):  
L.-U. SCHRADER ◽  
L. BRANDT ◽  
C. MAVRIPLIS ◽  
D. S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Free Stream ◽  
Three Dimensional ◽  
Low Frequency ◽  
Leading Edge ◽  
Sound Waves ◽  
Streamwise Vorticity ◽  
Low Frequencies ◽  
Free Stream Turbulence

Receptivity of the two-dimensional boundary layer on a flat plate with elliptic leading edge is studied by numerical simulation. Vortical perturbations in the oncoming free stream are considered, impinging on two leading edges with different aspect ratio to identify the effect of bluntness. The relevance of the three vorticity components of natural free-stream turbulence is illuminated by considering axial, vertical and spanwise vorticity separately at different angular frequencies. The boundary layer is most receptive to zero-frequency axial vorticity, triggering a streaky pattern of alternating positive and negative streamwise disturbance velocity. This is in line with earlier numerical studies on non-modal growth of elongated structures in the Blasius boundary layer. We find that the effect of leading-edge bluntness is insignificant for axial free-stream vortices alone. On the other hand, vertical free-stream vorticity is also able to excite non-modal instability in particular at zero and low frequencies. This mechanism relies on the generation of streamwise vorticity through stretching and tilting of the vertical vortex columns at the leading edge and is significantly stronger when the leading edge is blunt. It can thus be concluded that the non-modal boundary-layer response to a free-stream turbulence field with three-dimensional vorticity is enhanced in the presence of a blunt leading edge. At high frequencies of the disturbances the boundary layer becomes receptive to spanwise free-stream vorticity, triggering Tollmien–Schlichting (T-S) modes and receptivity increases with leading-edge bluntness. The receptivity coefficients to free-stream vortices are found to be about 15% of those to sound waves reported in the literature. For the boundary layers and free-stream perturbations considered, the amplitude of the T-S waves remains small compared with the low-frequency streak amplitudes.

scholarly journals Karakteristik Wake Area Akibat Efek Penggunaan Vortex Generator di Belakang Wing Airfoil Naca 43018

2019 ◽  
Vol 4 (1) ◽  
pp. 55-63
Author(s):  
Setyo Hariyadi S.P ◽  
Wawan Aries Widodo
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Drag Force ◽  
Lift Force ◽  
Vortex Generator ◽  
Leading Edge ◽  
O 15 ◽  
O 19 ◽  
Wing Airfoil

Pada aliran yang melintasi suatu airfoil terdapat fenomena separasi, yakni ketika momentum aliran sudah tidak mampu lagi mengatasi adverse pressure gradien. Selanjutnya separasi ini akan diikuti dengan timbulnya daerah wake pada daerah di belakang airfoil yang mengakibatkan naiknya drag force dan menurunnya lift force. Untuk mengurangi hal tersebut maka vortex generator diletakkan pada sisi atas airfoil untuk mempercepat terbentuknya turbulent boundary layer sehingga dapat menunda separasi dan memperkecil daerah wake. Efektivitas dari vortex generator dipengaruhi oleh penempatan, ketinggian, dan interval antar vortex generator. Untuk mendapatkan hasil yang optimal, drag yang dihasilkan oleh vortex generator itu sendiri harus dikurangi. Untuk itu profil dari vortex generator yang digunakan harus sedemikian rupa sehingga drag yang dihasilkan dapat dikurangi tanpa menurunkan performasi dari airfoil tersebut. Oleh karena itu, penelitian ini dilakukan untuk melihat pengaruh penambahan vortex generator terhadap unjuk kerja airfoil melalui metode eksperimen. Tujuan penelitian ini adalah membandingkan karakteristik aliran fluida plain wing dan dengan penambahan vortex generator. Profil vortex generator yang digunakan adalah flat plate vortex generator dengan konfigurasi straight dan ditempatkan pada x/c = 10% dan 20% arah chord line dari leading edge. Variasi yang digunakan adalah bilangan Reynolds (Re), sudut serang (α) dan peletakan vortex generator pada airfoil. Kecepatan freestream yang digunakan yaitu kecepatan 12 m/s atau Re = 7,65 x 105 dan kecepatan 17 m/s atau Re = 9 x 105, dan pada sudut serang (α) 0o, 3 o, 6 o, 9 o, 12 o, 15 o, 19 o, dan 20 o. Hasil penelitian ini menunjukkan bahwa terjadi peningkatan performansi dari airfoil NACA 43018 dengan penambahan vortex generator dibandingkan dengan tanpa vortex generator. Adanya vortex generator, mempercepat perubahan dari aliran laminar ke turbulen. Separasi dapat tertunda dengan adanya vortex generator.

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