scholarly journals Aerodynamic performance of several passive vortex generator configurations on an Ahmed body subjected to yaw angles

2021 ◽  
Vol 43 (3) ◽  
Author(s):  
H. Viswanathan
Keyword(s):  
Experimental Data ◽  
Vortex Generator ◽  
High Energy ◽  
Aerodynamic Performance ◽  
Vortex Generators ◽  
Leeward Side ◽  
Data Sets ◽  
Slant Angle ◽  
Delta Winglet ◽  
Ahmed Body

AbstractWe evaluate the aerodynamic performance of several passive vortex generators (VGs) placed on a standard Ahmed body, with a slant angle (α = 35º), subjected to different yawing angles (β) using RANS-based models. Rigorous validation of the numerical results is performed with previously published experimental data for (β ≤ 8º) for the Ahmed body. Our model results depict a good overall agreement with several experimental data sets. An array of different vortex generators such as the delta-winglet (DVGs), the cylindrical (CVGs) and trapezoidal (TVGs) types are introduced on to the validated model. The introduction of CVGs and DVGs tends to have a beneficial aerodynamic performance for (β = 0º). In contrast, the TVGs tend to impair the performance by producing massive flow separation over the slant for (β = 0º). Conversely, for (β > 0º), a swift transition happens with TVGs wherein the high-energy streamwise vortices that are produced tend to improve the pressure footprint, thereby reducing the overall drag. A deterioration in the performance of DVGs is predicted during (β > 4º), wherein the ‘c’-pillar vortex on the leeward side interferes with the streamwise vortical structure, which adversely influences the flow over the roof-slant edge. Overall, a maximum of ~ 8.5% and ~ 7.7% drag reduction appears to be possible with the designed CVGs and TVGs at smaller vehicle yawing conditions.

Fluid Flow and Heat Transfer Behavior for Turbulent Flows in a Tube With Vortex Generator Pairs for an Efficient Heat Exchanger

2018 ◽  
Author(s):  
Md. Islam ◽  
Z. Chong ◽  
S. Bojanampati
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Turbulent Flows ◽  
Flow Behavior ◽  
Vortex Generator ◽  
Tube Diameter ◽  
Vortex Generators ◽  
Blockage Ratio ◽  
Delta Winglet

Various technologies have been developed to enhance flow mixing and heat transfer in order to develop an efficient compact heat exchanging devices. Vortex generators/turbulent promoters generate the vortices which reduce the boundary layer thickness and introduce the better mixing of the fluid to enhance the heat transfer. In this research experimental investigations have been carried out to study the effect of delta winglet vortex generator pairs on heat transfer and flow behavior. To generate longitudinal vortex flow, two pairs of the delta winglet vortex generators (DWVG) with the length of 10mm and winglet-pitch to tube-diameter ratio (PR = 4.8) are mounted on the inner wall of a circular tube. The DWVG pairs with two different winglet-height to tube-diameter ratios (Blockage ratio, BR = 0.1 and 0.2), three attack angles (α = 10°, 20°, 30°) and three spacings between leading edges (S = 10, 15 and 20mm) are studied. The experiments were conducted with DWVGs pairs for the air flow range of Reynolds numbers 5000–25000. The influence of the DWVGs on heat transfer and pressure drop was investigated in terms of the Nusselt number and friction factor. The experimental results indicate that DWVG pair in a tube results in a considerable enhancement in Nusselt number (Nu) with some pressure penalty. It is found that DWVG increases Nu up to 85% over the smooth tube. It is also observed that Nusselt number increases with Re, blockage ratio and attack angle. Friction factor decreases with Re but increases with blockage ratio, spacing and attack angle. And 30° DWVG pair with S = 20mm, BR = 0.2 gets the highest friction factor. The Highest thermal performance enhancement (TPE) was noticed for α = 10°, S = 20mm, BR = 0.2 for turbulent flows. To obtain qualitative information on the flow behavior and vortex structures, flow was visualized by laser sheet using smoke as a tracer supplied at the entrance of the test section. The generation and development of longitudinal vortices influenced by DWVG pairs were clearly observed.

Numerical Simulation of Flow Around a Simplified Car Body

2003 ◽  
Author(s):  
Emmanuel Guilmineau
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Boundary Conditions ◽  
Turbulence Models ◽  
Test Case ◽  
Slant Angle ◽  
Acceptable Limit ◽  
Numerical Errors ◽  
Car Body ◽  
Ahmed Body

Simulations have been carried out for the generic car body (Ahmed body) for 25° and 35° slant angle. At a previous Workshop [1, 2], the results of different groups showed significant variations, even when the same turbulence models were used. This indicates that either the grids used in the investigation are too coarse to reduce the numerical errors below an acceptable limit, or that other factors, like boundary conditions, model implementation had a significant effect on the simulations. In any case, the results of the simulations were inconclusive, leading to a revaluation of this test case. In this study, we investigate numerically the flow around the Ahmed body for 25° and 35° slant angle. Results are compared with experimental data of Becker et al. [3].

Thermal enhancement of triangular fins based on spanwise distance of vortex generators

2016 ◽  
Vol 231 (13) ◽  
pp. 2554-2566
Author(s):  
Azize Akcayoglu ◽  
Celal Nazli
Keyword(s):  
Turbulence Model ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Local Flow ◽  
Flow And Heat Transfer ◽  
Inclined Surfaces ◽  
Thermal Enhancement ◽  
Flow Interactions ◽  
Delta Winglet ◽  
Global And Local

In this study, the influence of spanwise positions of vortex generators on the fin performance is determined numerically by considering global and local flow and heat transfer fields. The vortex generators are located on the inclined surfaces of equilateral triangular fins and the spanwise distances between them are altered as much as possible depending on the extents of the triangular duct. “RNG k-ɛ” turbulence model with “Enhanced wall treatment” option is determined as the best turbulence model to predict the flow fields inside the triangular fins with built-in vortex generators, for Reynolds number of 5000. It is found that the best performance is achieved when the spanwise distance between the common flow up and common flow down type vortex generator pairs and the triangular duct base are equal to 0.23 and 1.11 times the vortex generator length, respectively. The optimum spanwise distance between the vortex generators is determined as 0.88 times the vortex generator length. The determined values reinforced the secondary flow interactions including mixing of hot and cold fluids, generation of turbulence, swirling motion of vortices, and interaction of vortices with the main flow. The obtained results are useful in designing triangular heat exchangers with built-in delta-winglet type vortex generators.

scholarly journals Comparison of Different Fin and Tube Compact Heat Exchanger with Longitudinal Vortex Generator in CFU-CFD Configurations

2021 ◽  
Vol 39 (5) ◽  
pp. 1523-1531
Author(s):  
Katherine Barquín ◽  
Alvaro Valencia
Keyword(s):  
Heat Exchanger ◽  
Vortex Generator ◽  
Hydraulic Performance ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Tube Heat Exchanger ◽  
Tube Arrangement ◽  
First Case ◽  
Delta Winglet ◽  
Oval Tube

Over the last decades several studies have searched for improved Fin and Tube Heat Exchanger (FTHE) designs capable of providing the best thermo-hydraulic performance. The present study aims at quantifying and comparing the thermo-hydraulic performance of different FTHE configurations. Six different designs were analyzed. The first FTHE consisted of an in-line circular tube arrangement and the last one was a FTHE with staggered oval tube with two pairs of Delta Winglet Vortex Generators (DWVG) in common flow up–common flow down (CFU-CFD) configuration. The best performance was obtained using DWVG in CFU-CFD orientation. This configuration enabled a 90% increase of the thermal performance factor when compared with the first case, using only two pairs of vortex generator´s per tube.

scholarly journals Heat Transfer Characteristic on Wing Pairs Vortex Generator using 3D Simulation of Computational Fluid Dynamic

2021 ◽  
Vol 3 (2) ◽  
pp. 215-224
Author(s):  
Petrus Setyo Prabowo ◽  
◽  
Stefan Mardikus ◽  
Ewaldus Credo Eukharisto ◽  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Vortex Generator ◽  
Transfer Characteristic ◽  
Vortex Generators ◽  
Working Fluid ◽  
Longitudinal Vortices ◽  
Delta Winglet ◽  
Fluid Flow Characteristics

Vortex generators are addition surface that can increase heat transfer area and change the fluid flow characteristics of the working fluid to increase heat transfer coefficient. The use of vortex generators produces longitudinal vortices that can increase the heat transfer performance because of the low pressure behind vortex generators. This investigation used delta winglet vortex generator that was combined with rectangular vortex generator to Reynold numbers ranging 6,000 to 10,000. The parameters of Nusselt number, friction factor, velocity vector and temperature distribution will be evaluated.

Investigate aerodynamic performance of wind turbine blades with vortex generators at the transition area

2021 ◽  
pp. 0309524X2110385
Author(s):  
Zhou Wu ◽  
Tao Chen ◽  
Haipeng Wang ◽  
Hongwei Shi ◽  
Mingzhou Li
Keyword(s):  
Wind Turbine ◽  
Flow Separation ◽  
Turbine Blades ◽  
Simulation Method ◽  
High Energy ◽  
Aerodynamic Performance ◽  
Vortex Generators ◽  
Geometrical Parameters ◽  
Wind Turbine Blades ◽  
Transition Area

The transition area of the blade had a large relative thickness of airfoil, which was prone to the flow separation. The vortex generators (VGs) could restrain the flow separation. In this paper, the VGs were installed at the transition area of the WindPACT 1.5 MW wind turbine blades. The numerical simulation method was used to investigate the effects of the VGs on the aerodynamic performance of the blade. The high-energy vortexes were generated at the tail by the VG. It could change the energy distribution and flow characteristics of the airflow in the boundary layer. There were influences by the geometric parameters of the VGs. The VGs could change the aerodynamic performance at the transition area of the blade. A satisfactory result was obtained for reasonable geometrical parameters of the VGs. It also could restrain the flow separation of the blade surface and improve the torque.

Application of Jets and Vortex Generators to Improve Air-Cooling and Temperature Uniformity in a Simple Battery Pack

2018 ◽  
Vol 11 (2) ◽  
Author(s):  
Seham Shahid ◽  
Martin Agelin-Chaab
Keyword(s):  
Vortex Generator ◽  
Vortex Generators ◽  
Battery Pack ◽  
Maximum Temperature ◽  
Air Cooling ◽  
Temperature Uniformity ◽  
Numerical Studies ◽  
Battery Packs ◽  
Computational Fluid Dynamics Cfd ◽  
Delta Winglet

Abstract In this paper, the problem of air cooling and temperature nonuniformity at the cell and pack level is addressed. Passive techniques are developed by integrating jet inlets and vortex generators (VGs) in a simple battery pack with the goal to achieve an effective cooling, and the desired temperature uniformity at the cell and pack level to less than 5 °C, without an increase in the required mass flow and power requirements. Moreover, various configurations of the developed techniques are assessed and compared. In order to achieve the objectives, computational fluid dynamics (CFD) is used to conduct numerical studies on the battery packs. The results concluded that by adding both the delta winglet (DW) vortex generator arrays and jet inlet arrays in the same configuration, improvements in temperature reduction and uniformity can be achieved. The results showed that the maximum temperature of the battery pack was reduced by ∼6% and the temperature uniformity at the pack level was increased by 24%. Additionally, a ∼37% improvement in the temperature uniformity at cell level was achieved.

scholarly journals 3D Simulative Investigation of Heat Transfer Enhancement Using Three Vortex Generator Types Surrounding Tube in Plate Fin Heat Exchanger

2019 ◽  
Vol 130 ◽  
pp. 01027
Author(s):  
Stefan Mardikus ◽  
Petrus Setyo Prabowo ◽  
Vinsensius Tiara Putra ◽  
Made Wicaksana Ekaputra ◽  
Juris Burlakovs
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Pair Type ◽  
Tube Heat Exchanger ◽  
Performance Of Heat Transfer ◽  
Delta Winglet ◽  
The Heat Transfer Coefficient

Vortex generator is a method to enhancing of heat exchanger performance but still have some disadvantages when the heat transfer performance increase. One of the disadvantage using vortex generator is high pressure drop. This investigation will be compared three type vortex generators to result the overall performance of heat transfer around tube in plate fin heat exchanger. The three types of vortex generator to investigate are rectangular winglet type, delta winglet type, and trapezoidal winglet type in laminar flow. The result showed that using the kind of trapezoidal winglet pair type in the plate fin and tube heat exchanger consist of six rows of round tube with two neighboring fins form a channel better performance than two types vortex generators such as rectangular winglet type and delta winglet type. The heat transfer coefficient when use trapezoidal winglet type was increased almost same with rectangular winglet type and pressure drop was decreased more than delta winglet type.

Impact of Delta-Winglet Pair of Vortex Generators on the Thermal and Hydraulic Performance of a Triangular Channel Using Al2O3–Water Nanofluid

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Hamdi E. Ahmed ◽  
M. Z. Yusoff
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Volume Fraction ◽  
Vortex Generator ◽  
Attack Angle ◽  
Vortex Generators ◽  
Triangular Channel ◽  
Delta Winglet ◽  
The Heat Transfer Coefficient

This paper presents the laminar forced convection of Al2O3–water nanofluid in a triangular channel, subjected to a constant and uniform heat flux at the slant walls, using delta-winglet pair (DWP) of vortex generator which is numerically investigated in three dimensions. The governing equations of mass, momentum, and energy are solved using the finite volume method (FVM). The nanofluid properties are estimated as constant and temperature-dependent properties. The nanoparticle concentrations and diameters are in ranges of 1–4% and 25–85 nm, respectively. Different attack angles of vortex generators are examined which are 7 deg, 15 deg, 30 deg, and 45 deg with range of Reynolds number from 100 to 2000. The results show that the heat transfer coefficient is remarkable dependent on the attack angle of vortex generators and the volume fraction of nanoparticles. The heat transfer coefficient increases as the attack angle increases from 7 deg to 30 deg and then diminishes at 45 deg. The heat transfer rate remarkably depends on the nanoparticle concentration and diameter, attack angle of vortex generator and Reynolds number. An increase in the shear stress is found when attack angle, volume fraction, and Reynolds number increase.

Effects of Vortex-Vortex Interaction in a Compressor Cascade With Vortex Generators

2015 ◽  
Author(s):  
Tan Zheng ◽  
Xiaoqing Qiang ◽  
Jinfang Teng
Keyword(s):  
High Speed ◽  
Vortex Generator ◽  
Aerodynamic Performance ◽  
Extensive Study ◽  
Vortex Generators ◽  
Separation Flow ◽  
Vortex Interaction ◽  
Compressor Cascade ◽  
Corner Separation ◽  
Flow Phenomena

This paper presents a numerical investigation to explore the effects of vortex generators on a high speed compressor cascade. Secondary flow effects like the corner separation vortex have an influence on the performance of a compressor cascade such as leading to increased losses. In order to control the corner separation vortex and reduce losses, an extensive study of vortex generators applied to a compressor cascade is conducted. A preliminary study by steady 3D RANS simulations is performed using the Spalart-Allmaras turbulence model. The aerodynamic performance as well as the behavior of the corner separation vortex is investigated in the compressor cascade without vortex generators. Then, a vortex generator is added to the cascade, which is numerically simulated. Various configurations are considered, which are decided by the height and installation angle of the vortex generator. Comparison of the performance attained by these configurations results in an optimum scheme that has minimum losses. Furthermore, unsteady 3D DES simulations are performed with the optimum configuration. This method that predicts the flow field more precisely could help verify the accuracy of the RANS results. Finally, by analyzing all the resulting aerodynamic performance and numerical flow phenomena, the mechanism of vortex-vortex interaction is presented and discussed, which could be a criterion to reduce the corner separation flow and enhance the performance of axial compressors.

Sign in / Sign up

Export Citation Format

Share Document