Assessment of Flow Field Behind the Mechanical Vortex Generators at Mach 2.0

2021 ◽  
pp. 335-345
Author(s):  
C. Manisankar ◽  
S. B. Verma
Keyword(s):  
Flow Field ◽  
Vortex Generators

Heat Transfer Around Longitudinal and Parallel Arranged Wedge-Shaped Vortex Generators

2007 ◽  
Author(s):  
Marc Henze ◽  
Christopher Dietz ◽  
Jens von Wolfersdorf ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Rectangular Channel ◽  
Temperature Response ◽  
Vortex Pair ◽  
Reynolds Stress Model ◽  
Vortex Generators ◽  
Fluid Temperature ◽  
Thermochromic Liquid Crystal ◽  
Experimental Heat

In order to enhance convective heat transfer, turbulence promoters or vortex generators (VGs) are often used to manipulate the flow field and to benefit from their effect on thermal performance. The current investigation is directed towards a detailed understanding of the generated vortex flows and their impact on heat transfer for wedge shaped full-body VGs in internal flows. The main focus is on longitudinal and parallel arrangements of two or three VGs, where interaction of the induced flow field plays an important role. A single VG introduces a main vortex pair moving longitudinally downstream which is symmetric to the mid-plane of the turbulator itself. By using arrangements of several VGs it is possible to take advantage of the vortex interaction and define or deflect zones of enhanced heat transfer. In certain cases (e.g. due to manufacturing reasons) sharp edges on the elements cannot be realized. The effect of this discrepancy in the designated geometry is also investigated. Data for heat transfer behind a sharp-edged VG is compared with data for VGs manufactured with two different edge radii. In the present experimental setup the VGs are mounted on the bottom wall of a rectangular channel. For Reynolds numbers of 150,000 up to 550,000 the heat transfer coefficient is measured with the transient thermochromic liquid crystal (TLC) thermometry which is based on the measurement of the wall temperature response to a given step change in the fluid temperature. Numerical simulations using a Reynolds-Stress Model describe the flow field around the arrangements and are used for further interpretation of the experimental heat transfer distributions. Effects of vortex interactions on the heat transfer distribution are described for parallel and longitudinal arrangements. In the experimental data for elements with rounded edges a significant reduction in heat transfer can be observed.

scholarly journals Application of Vortex Generators in Flow Control of the Inlet

1985 ◽  
Author(s):  
Chen Xiao ◽  
Fang Liang-Wei
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Flow Separation ◽  
Dynamic Performance ◽  
Low Pressure ◽  
Transverse Flow ◽  
Vortex Generators ◽  
Flow Losses ◽  
Subsonic Diffuser ◽  
Selection Of

This paper introduces the features of using co-rotating vortex generators for controlling boundary layer and flow field in the inlet without flow separation. The principles of the arrangements of the blades and selection of constructional parameters of the generators that are applied to create the transverse flow between the high and low pressure regions and to reduce the secondary flow losses are analysed. The experimental results show that when the appropriate parameters of the co-rotating vortex generators are chosen for the inlet subsonic diffuser with apparent high and low pressure regions, not only the nonuniformity of the flow field is greatly improved but also the dynamic performance of the flow at exit is slightly improved.

558 Characteristics of Oscillation and Effect of a Flow Field of Flexible Vortex Generators in Supersonic Flows

2007 ◽  
Vol 2007.56 (0) ◽  
pp. 265-266
Author(s):  
Kanyu UEOKA ◽  
Kazuhiko YOKOTA ◽  
Motoyuki ITOH ◽  
Shinji TAMANO
Keyword(s):  
Flow Field ◽  
Supersonic Flows ◽  
Vortex Generators

The Effects of Vortex Structures on Heat Transfer and Flow Field behind Arrays of Vortex Generators

2009 ◽  
Vol 16 (2) ◽  
pp. 171-188 ◽  
Author(s):  
J. von Wolfersdorf ◽  
Bernhard Weigand ◽  
C. F. Dietz ◽  
S. O. Neumann ◽  
M. Henze
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Vortex Structures ◽  
Vortex Generators

Computational Investigation of a Race Car Wing With Vortex Generators in Ground Effect

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Yuichi Kuya ◽  
Kenji Takeda ◽  
Xin Zhang
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Flow Separation ◽  
Large Scale ◽  
Vortex Generator ◽  
Ground Effect ◽  
Experimental Results ◽  
Vortex Generators ◽  
Flow Physics ◽  
Large Scale Vortex

Vortex generators can be applied to control separation in flows with adverse pressure gradients, such as wings. In this paper, a study using three-dimensional steady computations for an inverted wing with vortex generators in ground effect is described. The main aim is to provide understanding of the flow physics of the vortex generators, and how they affect the overall aerodynamic performance of the wing to complement previous experimental studies of the same configuration. Rectangular vane type sub-boundary layer and large-scale vortex generators are attached to the suction surface of the wing, including both counter-rotating and co-rotating configurations. In order to provide confidence, Reynolds-averaged Navier–Stokes simulations using the Spalart–Allmaras turbulence model are validated against the experimental results regarding force, pressure, and wake characteristics, with the validation exhibiting close agreement with the experimental results. The streamwise friction shows the downwash induced by the generated vortex acts to suppress flow separation. The flow field survey downstream of the vortex generators features breakdown and dominance of the generated vortex in the flow. The vortex generated by the counter-rotating sub-boundary layer vortex generator grows in size and breaks down as it develops downstream, while the vortex generated by the counter-rotating large-scale vortex generator shows high vorticity even further downstream, indicating the persistence of the vortex in the flow. The flow field behind the co-rotating sub-boundary layer vortex generator is dominated by a lateral flow, having the spanwise flow component rather than a swirling flow, and the vortex quickly dissipating as it develops downstream. The results from this paper complement previous experimental measurements by highlighting the flow physics of how vortex generators can help control flow separation for an inverted wing in ground effect, and how critical vortex generator type and size are for its effectiveness.

Axis switching and spreading of an asymmetric jet: the role of coherent structure dynamics

1996 ◽  
Vol 316 ◽  
pp. 1-27 ◽  
Author(s):  
K. B. M. Q. Zaman
Keyword(s):  
Flow Field ◽  
Streamwise Vortex ◽  
Vortex Generators ◽  
Streamwise Vorticity ◽  
Vortical Structures ◽  
Vortex Pairs ◽  
Vorticity Dynamics ◽  
The Difference ◽  
Axis Switching

The effects of vortex generators and periodic excitation on vorticity dynamics and the phenomenon of axis switching in a free asymmetric jet are studied experimentally. Most of the data reported are for a 3:1 rectangular jet at a Reynolds number of 450 000 and a Mach number of 0.31. The vortex generators are in the form of ‘delta tabs’, triangular-shaped protrusions into the flow, placed at the nozzle exit. With suitable placement of the tabs, axis switching could be either stopped or augmented. Two mechanisms are identified governing the phenomenon. One, as described by previous researchers, is due to the difference in induced velocities for different segments of a rolled-up azimuthal vortical structure. The other is due to the induced velocities of streamwise vortex pairs in the flow. While the former mechanism, referred to here as the ωθ-dynamics, is responsible for a rapid axis switching in periodically forced jets, e.g. screeching supersonic jets, the effect of the tabs is governed mainly by the latter mechanism, referred to as the ωx-dynamics. Both dynamics can be active in a natural asymmetric jet; the tendency for axis switching caused by the ωθ-dynamics may be, depending on the streamwise vorticity distribution, either resisted or enhanced by the ωx-dynamics. While this simple framework qualitatively explains the various observations made on axis switching, mechanisms actually in play may be much more complex. The two dynamics are not independent as the flow field is replete with both azimuthal and streamwise vortical structures which continually interact. Phase-averaged measurements for a periodically forced case, over a volume of the flow field, are carried out in an effort to gain insight into the dynamics of these vortical structures. The results are used to examine such processes as the reorientation of the azimuthal vortices, the resultant evolution of streamwise vortex pairs, as well as the redistribution of streamwise vortices originating from secondary flow within the nozzle.

scholarly journals Using finite volume method for investigating the turbulent flow field and heat transfer of a non-Newtonian nanofluid in a channel with triangular vortex generators

2021 ◽  
Author(s):  
Muhammad Ibrahim ◽  
Tareq Saeed
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Field ◽  
Turbulent Flow ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Turbulent Flow Field ◽  
Volume Method

Abstract This study examines the turbulent flow field and heat transfer rate (HTR) of the non-Newtonian H2O-Al2O3-carboxymethyl (CMC) in a channel with vortex generators. The finite volume method and SIMPLE algorithm were employed for solving the partial differential equations. The mean Nusselt numbers (Num) and pressure drops were studied at angles of 30-60°, vortex generator depths of 1-3 mm, Reynolds numbers (Re) of 3000-30000, and nanoparticles volume fractions (φ) of 0.5% and 1.5%. According to the numerical results, the use of triangular vortex generators significantly incremented the Nusselt number (Nu) of the non-Newtonian nanofluid (NF), while it had a lower effect on the enhancement of pressure drop (DP). It was also indicated that a change in the vortex generator depth in the range of a few millimeters had no significant effects on the Nu and pressure drop. Moreover, a rise in the Re (i.e., more turbulent flow) significantly incremented HTR. An increase in the Re raised pressure drop; however, the Num incremented more than the pressure drop. Also, the variations of the local Nu indicated that the local Nu significantly incremented around vortex generators due to the formation of vortex flows. An enhancement in the volume fraction of the base fluid’s nanoparticles (NPs) from 0.5% to 1.5% significantly incremented HTR and the Nu.

THE EFFECTS OF VORTEX STRUCTURES ON HEAT TRANSFER AND FLOW FIELD BEHIND MULTIELEMENT ARRAYS OF VORTEX GENERATORS

Equipment ◽  
2006 ◽  
Author(s):  
C. F. Dietz ◽  
M. Henze ◽  
S. O. Neumann ◽  
J. von Wolfersdorf ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Vortex Structures ◽  
Vortex Generators
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