scholarly journals Investigasi Perbandingan Posisi Rectangular Flat Plate Vortex Generator dengan Posisi Straight pada Wing Airfoil NACA 43018

2018 ◽  
Vol 3 (3) ◽  
pp. 36-43
Author(s):  
Setyo Hariyadi S.P ◽  
Wawan Aries Widodo ◽  
Bambang Junipitoyo ◽  
Wiwid Suryono ◽  
Supriadi Supriadi
Keyword(s):  
Pressure Gradient ◽  
Flat Plate ◽  
Vortex Generator ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Wing Airfoil

Pesawat terbang merupakan aplikasi ilmu mekanika fluida yang sangat memperhatikan aspek aerodinamika karena berkaitan dengan performa pada penerbangan. Satu hal penting yang harus diperhatikan dalam pendesainan suatu pesawat yaitu pemilihan airfoil dan modifikasinya. Modifikasi airfoil dilakukan untuk menunda separasi aliran dan meningkatkan performa airfoil, salah satunya dengan vortex generator. Modifikasi pada airfoil dilakukan untuk meningkatkan performansi dari airfoil. Hal ini dapat diindikasikan dengan tertundanya separasi aliran yang melintasi permukaan atas dari airfoil. Dengan tertundanya separasi ini maka gaya lift akan semakin besar dan gaya drag akan semakin kecil. Penelitian sebelumnya menunjukkan bahwa penambahan vortex generator pada permukaan atas airfoil dapat menunda terjadinya separasi aliran. Hal ini disebabkan aliran lebih tahan melawan gaya gesek dan adverse pressure gradient. Topik yang dikaji dalam penelitian ini adalah aliran melintasi airfoil NACA 43018 dengan penambahan vortex generator. Airfoil NACA 43018 digunakan pada sayap pesawat terbang ATR 72. Tujuan penelitian ini adalah untuk membandingkan karakteristik aliran fluida dengan dan tanpa penambahan vortex generator. Profil vortex generator yang digunakan adalah rectangular 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) dan sudut serang (α) 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, 3o, 6o, 9o, 12o, 15o, 19o, dan 20o. Parameter yang dievaluasi meliputi koefisien tekanan (Cp), profil kecepatan, lift, drag, dan rasio CL/CD. Hasil penelitian ini menunjukkan bahwa terjadi peningkatan performansi dari airfoil NACA 43018 dengan penambahan vortex generator dibandingkan dengan tanpa vortex generator. Adanya vortex generator, dapat menunda terjadinya separasi. Dengan penambahan vortex generator terjadi peningkatan lift sekitar 5% dan menaikkan drag sekitar 1,5%. Rasio CL/CD meningkat sekitar 5 %.

scholarly journals STUDI NUMERIK PENGGUNAAN VORTEX GENERATOR PADA WING AIRFOIL NACA 43018

2019 ◽  
Vol 4 (3) ◽  
pp. 67-77
Author(s):  
Setyo Hariyadi Suranto Putro ◽  
Achmad Setiyo Prabowo
Keyword(s):  
Pressure Gradient ◽  
Flat Plate ◽  
Vortex Generator ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Wing Airfoil

Pesawat terbang merupakan aplikasi ilmu mekanika fluida yang sangat memperhatikan aspek aerodinamika karena berkaitan dengan performa pada penerbangan. Satu hal penting yang harus diperhatikan dalam pendesainan suatu pesawat yaitu pemilihan airfoil dan modifikasinya. Modifikasi airfoil dilakukan untuk menunda separasi aliran dan meningkatkan performa airfoil, salah satunya dengan vortex generator. Modifikasi pada airfoil dilakukan untuk meningkatkan performansi dari airfoil. Hal ini dapat diindikasikan dengan tertundanya separasi aliran yang melintasi permukaan atas dari airfoil. Dengan tertundanya separasi ini maka gaya lift akan semakin besar dan gaya drag akan semakin kecil. Penelitian sebelumnya menunjukkan bahwa penambahan vortex generator pada permukaan atas airfoil dapat menunda terjadinya separasi aliran. Hal ini disebabkan aliran lebih tahan melawan gaya gesek dan adverse pressure gradient. Topik yang dikaji dalam penelitian ini adalah aliran melintasi airfoil NACA 43018 dengan penambahan vortex generator. Airfoil NACA 43018 digunakan pada sayap pesawat terbang ATR 72. Tujuan penelitian ini adalah untuk membandingkan karakteristik aliran fluida dengan dan tanpa 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) dan sudut serang (α) 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, 3o, 6o, 9o, 12o, 15o, 19o, dan 20o. Parameter yang dievaluasi meliputi koefisien tekanan (Cp), profil kecepatan, gaya lift, gaya drag, dan rasio CL/CD. Hasil penelitian ini menunjukkan bahwa terjadi peningkatan performansi dari airfoil NACA 43018 dengan penambahan vortex generator dibandingkan dengan tanpa vortex generator. Adanya vortex generator, dapat menunda terjadinya separasi. Dengan penambahan vortex generator terjadi peningkatan gaya lift sekitar 5% dan menaikkan gaya drag sekitar 1,5%. Rasio CL/CD meningkat sekitar 5 %.

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.

Measurements in adverse-pressure-gradient turbulent boundary layers with a step change in surface roughness

1975 ◽  
Vol 70 (3) ◽  
pp. 573-593 ◽  
Author(s):  
W. H. Schofield
Keyword(s):  
Surface Roughness ◽  
Pressure Gradient ◽  
Boundary Layers ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Turbulent Boundary Layers ◽  
Step Change ◽  
Internal Layer ◽  
Mean Velocity ◽  
Law Of The Wall

The response of turbulent boundary layers to sudden changes in surface roughness under adverse-pressure-gradient conditions has been studied experimentally. The roughness used was in the ‘d’ type array of Perry, Schofield & Joubert (1969). Two cases of a rough-to-smooth change in surface roughness were considered in the same arbitrary adverse pressure gradient. The two cases differed in the distance of the surface discontinuity from the leading edge and gave two sets of flow conditions for the establishment and growth of the internal layer which develops downstream from a change in surface roughness. These conditions were in turn different from those in the zero-pressure-gradient experiments of Antonia & Luxton. The results suggest that the growth of the new internal layer depends solely on the new conditions at the wall and scales with the local roughness length of that wall. Mean velocity profiles in the region after the step change in roughness were accurately described by Coles’ law of the wall-law of the wake combination, which contrasts with the zero-pressure-gradient results of Antonia & Luxton. The skin-friction coefficient after the step change in roughness did not overshoot the equilibrium distribution but made a slow adjustment downstream of the step. Comparisons of mean profiles indicate that similar defect profile shapes are produced in layers with arbitrary adverse pressure gradients at positions where the values of Clauser's equilibrium parameter β (= δ*τ−10dp/dx) are similar, provided that the pressure-gradient history and local values of the pressure gradient are also similar.

On the Response of a Strongly Diffusing Flow to Propagating Wakes

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
J. P. Gostelow ◽  
R. L. Thomas ◽  
D. S. Adebayo
Keyword(s):  
Flat Plate ◽  
Large Scale ◽  
Separation Bubble ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Turbulent Spots ◽  
Stall Margin ◽  
Transverse Jet ◽  
Wide Range ◽  
Calming Effect

Further evidence on the similarities between transition and separation phenomena occurring in turbomachinery and wind tunnel flows is provided by measurements on a large scale flat plate under a strong adverse pressure gradient. The flat plate has a long laminar separation bubble and is subjected to a range of disturbances with triggering caused by injection of a transverse jet and subsequently by wakes generated by rods moving transversely upstream of the leading edge. Wakes were originally presented individually. Each individual wake provoked a vigorous turbulent patch, resulting in the instantaneous collapse of the separation bubble. This was followed by a very strong, and stable, calmed region. Following the lead given by the experiments of Gutmark and Blackwelder (1987, “On the Structure of Turbulent Spot in a Heated Laminar Boundary Layer,” Exp. Fluids, 5, pp. 207–229.) on triggered turbulent spots, wakes were then presented in pairs at different wake spacing intervals. In this way wake interaction effects could be investigated in more detail. As in the work on triggered turbulent spots the spacing between impinging wakes was systematically varied; it was found that for close wake spacings the calmed region acted to suppress the turbulence in the following turbulent patch. To investigate whether this phenomenon was a recurring one or whether the flow then reverted back to its unperturbed state, the experiments were repeated with three and four rods instead of two. This has the potential for making available a wide range of variables including direction and speed of rod rotation. It was found that the subsequent wakes were also suppressed by the calming effect. It may be anticipated that this repeating situation is present in a turbomachine, resulting in hidden benefits for blade count and efficiency. There may also conceivably be blade loading advantages while retaining favorable heat transfer conditions in high pressure turbines or stall margin in axial compressors. The inherent and prospective benefits of the calming effect therefore need to be understood thoroughly and new opportunities exploited where this is feasible.a

Reynolds Averaged Navier Stokes Models Compared to Direct Numerical Simulations in an Adverse Pressure Gradient Boundary Layer Over a Flat Plate

2013 ◽  
Author(s):  
Daniel Routson ◽  
James Ferguson ◽  
John Crepeau ◽  
Donald McEligot ◽  
Ralph Budwig
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
National Laboratory ◽  
Adverse Pressure Gradient ◽  
Skin Friction Coefficient ◽  
Navier Stokes ◽  
Transition Model ◽  
Wall Functions ◽  
Reynolds Averaged Navier Stokes

In Reynolds-Averaged Navier Stokes (RANS) models simplifying assumptions breakdown in near wall regions. Wall functions/treatments become inaccurate and the homogeneity and isotropy models may not hold. To see the effect that these assumptions have on the validity of boundary layer results in a commercially available RANS code, key boundary layer parameters are compared from laminar, transitional, and fully turbulent RANS results to an existing direct numerical simulation (DNS) simulation for flow over a flat plate with an adverse pressure gradient (APG). Parameters compared include velocity profiles in the free stream, boundary layer thicknesses, skin friction coefficient and the pressure gradient parameter. Results show comparable momentum thickness and pressure gradient parameters between the transition RANS model and the DNS simulation. Differences in the onset of transition between the RANS transition model and DNS are compared as well. These simulations help evaluate the models used in the RANS code. Of most interest is the transition model, a transition shear-stress transport (SST) k–omega model. The RANS code is being used in conjunction with an APG boundary layer experiment being undertaken at the Idaho National Laboratory (INL).

scholarly journals Investigation of Laminar Separation Bubble on Flat Plate with Adverse Pressure Gradient: Time-Averaged Flow Field Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yonglei Qu ◽  
Dario Barsi ◽  
Daniele Simoni ◽  
Pietro Zunino ◽  
Yigang Luan
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flat Plate ◽  
Pressure Coefficient ◽  
Adverse Pressure Gradient ◽  
Physical Parameters ◽  
Numerical Work ◽  
Laminar Separation ◽  
Flow Phenomena ◽  
Rans Simulations

The performance of turbomachinery blade profiles, at low Reynolds numbers, is influenced by laminar separation bubbles (LSBs). Such a bubble is caused by a strong adverse pressure gradient (APG), and it makes the laminar boundary layer to separate from the curved profile surface, before it becomes turbulent. The paper consists on a joint experimental and numerical investigation on a flat plate with adverse pressure gradient. The experiment provides detailed results including distribution of wall pressure coefficient and boundary layer velocity and turbulence profiles for several values of typical influencing parameters on the behavior of the flow phenomena: Reynolds number, free stream turbulence intensity, and end-wall opening angle, which determines the adverse pressure gradient intensity. The numerical work consists on carrying out a systematic analysis, with Reynolds Average Navier-Stokes (RANS) simulations. The results of the numerical simulations are critically investigated and compared with the experimental ones in order to understand the effect of the main physical parameters on the LSB behavior. For RANS simulations, different turbulence and transition models are compared at first to identify the adaptability to the flow phenomena; then, the influence of the three aforementioned parameters on the LSB behavior is investigated under a typical aggressive adverse pressure gradient. Boundary layer integral parameters are discussed for the different cases in order to understand the flow phenomena in terms of flow time-mean properties.

scholarly journals RANS-based design of experimental flow model for investigation of complex curved turbulent wakes subjected to adverse pressure gradient

2021 ◽  
Vol 2103 (1) ◽  
pp. 012203
Author(s):  
E K Guseva ◽  
D A Nikulin ◽  
A K Travin ◽  
R Radespiel ◽  
P Scholz
Keyword(s):  
Pressure Gradient ◽  
Flat Plate ◽  
Flow Model ◽  
Flow Region ◽  
Adverse Pressure Gradient ◽  
Turbulent Wake ◽  
Wake Flows ◽  
Wide Range ◽  
Reversal Flow ◽  
The One

Abstract Results are presented of a series of RANS computations aimed at creating a new experimental flow model of a curved turbulent wake evolving under adverse pressure gradient. In the course of the computations, key geometric parameters of the model (the angle of attack of a flat plate generating the wake and the shape and the angles of attack of liner foils creating the pressure gradient) were varied in a wide range. The purpose was to find the parameters ensuring desirable features of the flow, namely, a considerable wake curvature and its strong deceleration leading to formation of a large stagnation or even a reversal flow region, on the one hand, and no flow separation either from the flat plate or from the surfaces of the liner foils, on the other hand. As a result, the design satisfying all these demands has been found. This design will be implemented and studied in the framework of recently launched joint German-Russian project “Complex Wake Flows” which presents a continuation of an earlier similar project devoted to symmetric wakes.

Calculation of Transition in Adverse Pressure Gradient Flow by Conditioned Equations

1996 ◽  
Author(s):  
J. Steelant ◽  
E. Dick
Keyword(s):  
Pressure Gradient ◽  
Transport Equation ◽  
Stokes Equations ◽  
Growth Parameter ◽  
Gradient Flow ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations

Conditionally averaged Navier-Stokes equations are used to describe transitional flow in adverse pressure gradient combined with a transport equation for the intermittency factor γ. A transport equation developped in earlier work has been modified to eliminate the use of a distance along a streamline. An extension of the correlations is proposed to determine the spot growth parameter in adverse pressure gradient. This approach is verified against flows over a flat plate with an elliptical leading edge.

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