Academic literature on the topic 'Vortex generator (VG)'
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Journal articles on the topic "Vortex generator (VG)"
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Gutierrez-Amo, Ruben, Unai Fernandez-Gamiz, Iñigo Errasti, and Ekaitz Zulueta. "Computational Modelling of Three Different Sub-Boundary Layer Vortex Generators on a Flat Plate." Energies 11, no. 11 (2018): 3107. http://dx.doi.org/10.3390/en11113107.
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Flow separation is the source of several problems in a wind turbine including load fluctuations, lift losses, and vibrations. Vortex generators (VGs) are passive flow control devices used to delay flow separation, but their implementation may produce overload drag at the blade section where they are placed. In the current work, a computational model of different geometries of vortex generators placed on a flat plate has been carried out throughout fully meshed computational simulations using Reynolds Averaged Navier-Stokes (RANS) equations performed at a Reynolds number of R e θ = 2600 based on local boundary layer (BL) momentum thickness θ = 2.4 mm. A flow characterization of the wake behind the vortex generator has been done with the aim of evaluating the performance of three vortex generator geometries, namely Rectangular VG, Triangular VG, and Symmetrical VG NACA0012. The location of the primary vortex has been evaluated by the vertical and lateral trajectories and it has been found that for all analyzed VG geometries the primary vortex is developed below the boundary layer thickness δ = 20 mm for a similar vorticity level ( w x m a x ). Two innovative parameters have been developed in the present work for evaluating the vortex size and the vortex strength: Half-Life Surface S 05 and Mean Positive Circulation Γ 05 + . As a result, an assessment of the VG performance has been carried out by all analyzed parameters and the symmetrical vortex generator NACA0012 has provided good efficiency in energy transfer compared with the Rectangular VG.
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Al-Akam, Aws, Hanan K. Kadhim, Sarmad Asi Ali, and Ameen M. Al Juboori. "Numerical Analysis for the Airflow Behaviour around Vortex Generators Used for Air-Cooling Technologies Considering Rotation." CFD Letters 17, no. 9 (2025): 127–44. https://doi.org/10.37934/cfdl.17.9.127144.
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This study investigates the airflow behaviour around vortex generators (VG) utilized in air-cooling technologies, considering the impact of rotation. The analysis encompasses a numerical approach to study the flow around vortex generators (conventional and curved delta winglet type) installed inside a duct with a heated wall. The vortex generators' set number effect on the heat transfer behaviour was investigated. Three sets of vortex generators were examined, two-VG set, four-VG set and six-VG set, equally aligned along the duct. The range of Reynolds numbers (Re) from 4000 to 12000, with the rotation number (Ro) fixed at 0.20 is covered. In this study, the thermal behaviour (measured by Nusselt Number (Nu)) and the flow behaviour (represented by) the friction factor (f)) were presented. Validation for the employed numerical model was performed based on the available experimental outcomes. The impact of using the vortex generator was evaluated and compared with the clean duct, the duct with conventional delta winglet and the curved one. The results revealed that installing the vortex generator increases the Nu (by 1.34 times at Re 4000 for four-VG and two-VG sets) and reduces the friction factor. Additionally, using the newly designed curved VG increased Nu by about 1.35. However, as the number of employed VGs enlarged, the rate of increase declined to about 0.9 of the Nusselt number value associated with the conventional VG. Furthermore, f (friction factor) reduces with the number of VG and increases with Re. In all cases, the rotation increases the Nu and f factor and using the curved VG showed a higher rate of increase. The newly designed VGs showed improved heat transfer behaviour, performing best with a four-VG set installed and worst with a six-VG set.
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Hansen, M. O. L., and K. Rogowski. "Investigation of a delta wing Vortex Generator." Journal of Physics: Conference Series 2265, no. 3 (2022): 032037. http://dx.doi.org/10.1088/1742-6596/2265/3/032037.
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Abstract The flow and the effect on a DU08-W-210 airfoil using a conventional and a delta wing vortex generator (VG) has been investigated numerically using ANSYS Fluent and STAR CCM+ CFD solvers. The numerical results from the two CFD programs are very consistent. Both VG geometries delay boundary separation at the trailing edge of the airfoil and thus increase the lift and lift to drag ratio. The overall aerodynamic loads on the airfoil are quite similar for the two different VG geometries, but the created vortices give a slightly different distribution of the skin friction in the wake behind the VGs. The vortex created by the delta wing VG for the same conditions and size as the conventional triangular VG is slightly stronger and probably caused by the fact that the surface creating the vortices is placed higher up in the boundary layer and thus experience a higher inflow velocity. A method to measure the strength and core radius of the created vortices using a Lamb-Ossen vortex is described.
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Ibarra-Udaeta, Iosu, Iñigo Errasti, Unai Fernandez-Gamiz, Ekaitz Zulueta, and Javier Sancho. "Computational Characterization of a Rectangular Vortex Generator on a Flat Plate for Different Vane Heights and Angles." Applied Sciences 9, no. 5 (2019): 995. http://dx.doi.org/10.3390/app9050995.
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Vortex generators (VG) are passive flow control devices used for avoiding or delaying the separation of the boundary layer by bringing momentum from the higher layers of the fluid towards the surface. The Vortex generator usually has the same height as the local boundary layer thickness, and these Vortex generators can produce overload drag in some cases. The aim of the present study was to analyze the characteristics and path of the primary vortex produced by a single rectangular vortex generator on a flat plate for the incident angles of β = 10 ∘ , 15 ∘ , 18 ∘ and 20 ∘ . A parametric study of the induced vortex was performed for six VG heights using Reynolds average Navier–Stokes equations at Reynodls number R e = 27,000 based on the local boundary layer thickness, using computational fluid dynamics techniques with OpenFOAM open-source code. In order to determine the vortex size, the so-called half-life radius was computed and compared with experimental data. The results showed a similar trend for all the studied vortex generator heights and incident angles with small variations for the vertical and the lateral paths. Additionally, 0.4H and 0.6H VG heights at incident angles of β = 18 ∘ and β = 20 ∘ showed the best performance in terms of vortex strength and generation of wall shear stress.
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Chung, Ping-Han, Po-Hsiang Chang, and Szu-I. Yeh. "The Aerodynamic Effect of an Alula-like Vortex Generator on a Revolving Wing." Biomimetics 7, no. 3 (2022): 128. http://dx.doi.org/10.3390/biomimetics7030128.
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An alula is a small structure of feathers that prevents birds from stalling. In this study, the aerodynamic effect of an alula-like vortex generator (alula-VG) on a revolving wing was investigated using the PIV technique in a water tank. The alula-VG was mounted on a rectangular wing model at two spanwise positions. The wing model with a revolving motion was installed at different angles of attack, which included pre-stall and post-stall conditions. The velocity fields around the wing model with/without an alula-VG were measured and analyzed, including the vorticity contour, the circulation of vortex structures, and the corresponding sectional lift coefficient, which are used to explain the aerodynamic effect induced by an alula-VG. The lift-off and bursting of the leading-edge vortex (LEV) affect the magnitude of the chordwise circulation and the section lift coefficient. The results show that compared to an alula-VG mounted fixed wing model, the flow interactions among the alula-VG induced spanwise flow, the inertial force caused by the revolving motion, and the wing-tip vortex play important roles in the vortex bursting and the resultant aerodynamic performance. The effect of an alula-VG on a revolving wing depends on its spanwise position and the angle of attack of a wing model, which need to be properly matched.
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Hansen, Martin O. L., Antonis Charalampous, Jean-Marc Foucaut, Christophe Cuvier, and Clara M. Velte. "Validation of a Model for Estimating the Strength of a Vortex Created from the Bound Circulation of a Vortex Generator." Energies 12, no. 14 (2019): 2781. http://dx.doi.org/10.3390/en12142781.
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A hypothesis was tested and validated for predicting the vortex strength induced by a vortex generator in wall-bounded flow by combining the knowledge of the Vortex Generator (VG) geometry and the approaching boundary layer velocity distribution. In this paper, the spanwise distribution of bound circulation on a vortex generator was computed by integrating the pressure force along the VG height, calculated using Computational Fluid Dynamics (CFD). It was then assumed that all this bound circulation was shed into a wake to fulfill Helmholtz’s theorem which then curls up into one primary tip vortex. To validate this, the trailed circulation estimated from the distribution of the bound circulation was compared to the one in the wake behind the vortex generator, determined directly from the wake velocities at some downstream distance. In practical situations, the pressure distribution on a vane is unknown and consequently other estimates of the spanwise force distribution on a VG must instead be applied, such as using 2D airfoil data corresponding to the VG geometry at each wall-normal distance. Such models have previously been proposed and used as an engineering tool to aid preliminary VG design. Therefore, it is not the purpose of this paper to refine such engineering models, but rather to validate their assumptions, such as applying a lifting line model on a VG that has a very low aspect ratio and is placed in a wall boundary layer. Herein, high Reynolds number boundary layer measurements of VG-induced flow were used to validate the Reynolds-Averaged Navier–Stokes (RANS) model circulation results, which were used for further illustration and validation of the hypothesis.
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Li, Xin-Kai, Wei Liu, Ting-Jun Zhang, Pei-Ming Wang, and Xiao-Dong Wang. "Experimental and Numerical Analysis of the Effect of Vortex Generator Installation Angle on Flow Separation Control." Energies 12, no. 23 (2019): 4583. http://dx.doi.org/10.3390/en12234583.
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In order to explore the effect of the installation angle of vortex generator (VG) on boundary-layer flow control, the vortex characteristics of plate VG and their effect on the aerodynamic characteristics of an airfoil was studied numerically and using wind tunnel experiments. The effects of five VG installation angles (β) of 10°, 15°, 20°, 25°, and 30° on the characteristics of vortices were studied. The results show that the strength of vortices on the leeward side of VG increases with an increased installation angle until, eventually, the vortex core breaks down. During the downstream development of the VG leading-edge separation vortices, these vortices deviate in the radial direction. The larger the installation angle, the larger this deviation distance in the radial direction becomes. The effects of installation angle on the aerodynamic performance of airfoils were studied in a wind tunnel using the same five VG installation angles. The results show that VG can delay flow separation on the airfoil suction surface, thereby increasing lift and reducing drag. The stall angle of the airfoil with VG was increased by 10°. When the installation angle of the VG was 20°, the maximum lift coefficient of airfoil increased by 48.77%. For an airfoil angle of attack (AoA) of 18°, the drag of the airfoil decreased by 88%, and the lift-drag ratio increased by 1146.04%. Considering the best overall distribution of lift-drag ratio, the positive effect of the VG was found to be when β = 20° and the worst VG effectiveness was observed at β = 30°.
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Syaiful, Imam Syarifudin, Maria F. Soetanto, and Myung-whan Bae. "Numerical simulation of heat transfer augmentation in fin-and-tube heat exchanger with various number of rows of concave rectangular winglet vortex generator." MATEC Web of Conferences 159 (2018): 02012. http://dx.doi.org/10.1051/matecconf/201815902012.
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The passive method by using a vortex generator (VG) is an effective method for the improvement of convective heat transfer. This study is focused on usage of concave rectangular winglet vortex generator (CRW VG) for improving convective heat transfer in a fin-and-tube heat exchanger using numerical simulation. Concave rectangular winglet pairs (CRWP) and rectangular winglet pairs (RWP) VGs were mounted inside the gap between fins (gas side) with variations of the number of VG pairs of rows. Inlet air velocity variations expressed by the Reynolds numbers were ranged from 364 to 689. Augmentation of heat transfer is indicated by the ratio value of heat transfer convection coefficient between cases using VG and that without using VG (baseline). The results show that the convection heat transfer coefficient for cases using CRWP VG is higher than that using RWP VG. Convection heat transfer coefficient increases up to 102% by mounting CRWP VG at Re = 364. However, the increase in convection coefficient is accompanied by a rise in pressure drop to 216.8%.
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Zainondin, Muhammad Amirul Hakimin, Izuan Amin Ishak, Mohd Fuad Yasak, Mohammad Arafat, Nor Atiqah Zolpakar, and Nurshafinaz Mohd Maruai. "Numerical Analysis on the Aerodynamic Characteristics of SUV Car Model Install with Vortex Generator." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 125, no. 1 (2024): 94–111. https://doi.org/10.37934/arfmts.125.1.94111.
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The investigation of automotive aerodynamics involves analysing several forces operating on a car while driving on the road, such as drag and lift forces. The flow separation at the vehicle's rear end is one of the primary causes of aerodynamic drag for automobile vehicles. It is feasible to improve fuel efficiency by lowering the drag force. The study focuses on the influence of a vortex generator (VG) on the aerodynamics of a sport utility vehicle (SUV) car. The study aims to simulate fluid flow analysis for an SUV car that uses VG and without VG, as well as to assess the impact of a different configuration of VG and a varying number and fillet radius of VG. The number of VG are 3, 5, and 9. The different fillet radius of VG are 5, 10, and 15 mm. Using the Reynold-Averaged Navier Stokes Equation (RANS) in the numerical simulation, the Reynolds number at the computational domain is 1.1391 × 107 and 1.4808 × 107, which is determined by the height of the model and the freestream velocity. The results show that aerodynamic characteristics are significantly influenced by the number of VG and various size radius fillets of VG. From the result, 9 number of VG and 5 mm fillet radius obtained the lowest value of coefficient of drag, Cd compared with the others which is Cd = 0.3747 for 27.78 m/s and Cd = 0.5031 for 33.33 m/s, respectively. Furthermore, the analysis of flow structures suggested the locations of vortex formation and wake turbulence at the rear of the vehicle. In contrast, the 9 number of VG with a 5 mm radius fillet of VG emerged as the most suitable VG for this scenario, exhibiting a Cd value closest to the base model and the lowest Cd value.
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Li, Xin-kai, Wei Liu, Ting-jun Zhang, Pei-ming Wang, and Xiao-dong Wang. "Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control." Applied Sciences 9, no. 24 (2019): 5495. http://dx.doi.org/10.3390/app9245495.
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During the operation of wind turbines, flow separation appears at the blade roots, which reduces the aerodynamic efficiency of the wind turbine. In order to effectively apply vortex generators (VGs) to blade flow control, the effect of the VG spacing (λ) on flow control is studied via numerical calculations and wind tunnel experiments. First, the large eddy simulation (LES) method was used to calculate the flow separation in the boundary layer of a flat plate under an adverse pressure gradient. The large-scale coherent structure of the boundary layer separation and its evolution process in the turbulent flow field were analyzed, and the effect of different VG spacings on suppressing the boundary layer separation were compared based on the distance between vortex cores, the fluid kinetic energy in the boundary layer, and the pressure loss coefficient. Then, the DU93-W-210 airfoil was taken as the research object, and wind tunnel experiments were performed to study the effect of the VG spacing on the lift–drag characteristics of the airfoil. It was found that when the VG spacing was λ/H = 5 (H represents the VG’s height), the distance between vortex cores and the vortex core radius were approximately equal, which was more beneficial for flow control. The fluid kinetic energy in the boundary layer was basically inversely proportional to the VG spacing. However, if the spacing was too small, the vortex was further away from the wall, which was not conducive to flow control. The wind tunnel experimental results demonstrated that the stall angle-of-attack (AoA) of the airfoil with the VGs increased by 10° compared to that of the airfoil without VGs. When the VG spacing was λ/H = 5, the maximum lift coefficient of the airfoil with VGs increased by 48.77% compared to that of the airfoil without VGs, the drag coefficient decreased by 83.28%, and the lift-to-drag ratio increased by 821.86%.
Dissertations / Theses on the topic "Vortex generator (VG)"
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Harris, Christopher A. "Acoustics and Fluid Dynamics Studies of High Speed Jet Noise Reduction Devices." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218687698.
Full textBook chapters on the topic "Vortex generator (VG)"
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Syaiful and M. Kurnia Lutfi. "Numerical Investigation of Heat Transfer and Fluid Flow Characteristics in a Rectangular Channel with Presence of Perforated Concave Rectangular Winglet Vortex Generators." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96117.
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The high thermal resistance of the airside of the compact heat exchanger results in a low heat transfer rate. Vortex generator (VG) is one of the effective passive methods to increase convection heat transfer by generating longitudinal vortex (LV), which results in an increase in fluid mixing. Therefore, this study aims to analyze the convection heat transfer characteristics and the pressure drop of airflow in a rectangular channel in the presence of a concave rectangular winglet VG on a heated plate. Numerical calculations were performed on rectangular winglet pairs vortex generators (RWP VGs) and concave rectangular winglet pairs vortex generators (CRWP VGs) with a 45° angle of attack and one, two, and three pairs of VGs with and without holes. The simulation results show that the decrease in the value of convection heat transfer coefficient and pressure drop on CRWP with three perforated VG configuration is 4.63% and 3.28%, respectively, of the three pairs of CRWP VG without holes at an airflow velocity of 2 m/s.
Conference papers on the topic "Vortex generator (VG)"
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BONIFACE, Jean-Christophe. "A Computational Framework for Helicopter Fuselage Drag Reduction Using Vortex Generators." In Vertical Flight Society 70th Annual Forum & Technology Display. The Vertical Flight Society, 2014. http://dx.doi.org/10.4050/f-0070-2014-9444.
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A computational framework has been developed for the CFD computation of a blunt helicopter fuselage equipped with vortex generators (VG). The VG are explicitly discretized in the CFD mesh, within the use of the overset grid method. A dedicated mesh generator developed at ONERA has been improved together with an all-in-one computational set-up, allowing parametric investigations for VG arrangement, shape, position, and size effects. The methodology has been applied to a down-scaled GOAHEAD-like wind-tunnel model, for drag reduction by passive flow control on the backdoor surface at cruise-flight conditions. A test-matrix has been completed and a reference VG configuration was identified as promising for an array of 2x8 counter-rotating VG with zero-thickness vane-type like planform. The VG were sized according to the approximated boundary-layer thickness following classical integral formulation for a longitudinal flow. At cruise conditions, the VG configuration achieves about 5% total drag reduction by strongly reducing the extension of the separated flow at the backdoor/tail boom junction. The proposed reference VG configuration will be tested during a wind-tunnel test campaign for the same GOAHEAD-like downscaled model.
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Onishi, Hajime, Haruka Yonekura, Yukio Tada, and Akira Takimoto. "Heat Transfer Performance of Finless Flat Tube Heat Exchanger With Vortex Generator." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23232.
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As the longitudinal vortex is known to be effective in enhancing heat transfer, a three-dimensional unsteady numerical analysis has been made especially for the flow and thermal fields in a unit element of flat tube heat exchanger with vortex generator (VG) in so-called middle Reynolds number range. Both staggered and in-lined arrangements of the tubes with VG are considered and results obtained from the case with VG are compared with those without VG. The study was aimed at the influence of Reynolds number and some geometrical parameters on the heat transfer and the pressure drop. Moreover, as little research has been considered the interaction between transverse vortices and longitudinal vortices in the literatures, the effect is also investigated. It is found that the longitudinal vortex plays an important role in enhancing the local heat transfer by exchanging the fluid from the tube surface region to the fresh fluid of the main flow region and lasts over long distances. Moreover, the longitudinal vortices restrain unsteady transverse vortex shedding. As a result, heat transfer rate for the flat tube with VG case is larger compared to that without VG case. From the view point of pressure drop, increase in pressure drop for the case with VG is not so much larger due to the restraint of transverse vortex shedding. Finally, heat transfer performance becomes higher for the flat tube with VG case compared to that without VG case for the same pumping power.
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Agarwal, Ruchika, Anand Dhamarla, Sridharan R. Narayanan, Shraman N. Goswami, and Balamurugan Srinivasan. "Numerical Investigation on the Effect of Vortex Generator on Axial Compressor Performance." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25329.
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The performance of the compressor blade is considerably influenced by secondary flow effects, like the cross flow on the end wall as well as corner flow separation between the wall and the blade. The present work is focused on the studying the effects of Vortex Generator (VG) on NASA Rotor 37 test case using Computational Fluid Dynamics (CFD). VG helps in controlling the inception of the stall by generating vortices and energizes the low momentum boundary layer flow which enhances the rotor performance. Three design configuration namely, Counter-rotating, Co-rotating and Plow configuration VG are selected based on the improved aerodynamic performance discussed in reference [1]. These VG are located at 90% span and 42% chord on suction side surface of the blade. Among the three configurations, the first configuration has greater impact on the end wall cross flow and flow deflection which resulted in enhanced numerical stall margin of 5.4% from baseline. The reasons for this numerical stall margin improvement are discussed in detail.
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Hussain, Sadam, and Xin Yan. "Implementation of Vortex Generator and Ramp to Improve Film Cooling Effectiveness on Blade Endwall." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59530.
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Abstract With the arrangements of vortex generators (VG) and ramp, film cooling effects on endwall near leading edge were numerically investigated at two blowing ratios (i.e. M = 0.5 and M = 1). To determine suitable numerical methods, mesh independency analysis and turbulence model selection were carried out based on the existing experimental data and LES results. With the numerical methods, flow fields near the leading edge were visualized to illustrate the influence of VG and ramp on coolant coverage on blade endwall. Film cooling effectiveness distributions on endwall and coolant trajectories near leading edge were compared among five different configurations with VG and ramp. The results show that the attachment of coolant on blade endwall is improved with the implement of VG between shaped-hole and leading edge. With the implementation of ramp on endwall between cooling hole and leading edge, the coolant spreads wider on endwall along pitchwise direction than the baseline case. With the implementation of VG and ramp, film cooling effect on endwall near leading edge is significantly improved as compared with the only ramp and only VG cases. Compared with the baseline case, pitchwise-averaged film cooling effectiveness on blade endwall near leading edge is increased by about 9%, and the film cooling effectiveness distributions on endwall along pitchwise direction become much uniform, for the case with both ramp and VG at M = 1.
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Wang, Wen, Jiahuan Cui, and Shaoxing Qu. "Large-Eddy Simulation of Film Cooling Performance Enhancement Using Vortex Generator and Semi-Sphere." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14787.
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Abstract Film cooling is an essential cooling method to prevent high-pressure turbine blade from melting down due to the high inlet temperature. In order to improve the film cooling efficiency, several flow control methods have been proposed. In this paper, large-eddy simulations are performed to study the effectiveness of a vortex generator (VG) and a semi-sphere installed downstream of the cooling jet. Before the detailed analyses, the numerical framework is validated against the available experimental data. Both the laminar and turbulent approaching boundary layers are considered. The turbulent boundary layer is generated by a numerical plasma actuator. After validation, the influence of VG and semi-sphere on the film cooling efficiency at various blowing ratios are analyzed. It is found that a counter-rotating vortex pair (CVP) is formed downstream and its strength increases with the blowing ratio in the configuration without VG/semi-sphere. When the VG is installed, it produces another vortex pair that rotates in the reverse direction of the CVP, which reduces the CVP strength and increases the lateral diffusion of the coolant. As a result, the film cooling efficiency is greatly improved, especially at a higher blowing ratio. For the case with a semi-sphere, the film cooling efficiency is also improved, especially at low–medium blowing ratios. However, it is not as effective as the VG in terms of enhancing cooling efficiency. In addition, the total pressure loss is calculated to examine the aerodynamic penalty associated with the VG and semi-sphere. It is found that the total pressure loss increased by only 1% due to the VG or semi-sphere, within the range of blowing ratio investigated in the current study. Considering the overall performance and the feasibility of being applied in practice, a semi-sphere installed downstream of the cooling hole is a promising method to improve the cooling efficiency.
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Rastan, Hamidreza, Tim Ameel, and Björn Palm. "Parametric Study of Vortex Generator Effects in an Additive Manufactured Minichannel Heat Exchanger." In ASME 2019 17th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/icnmm2019-4236.
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Abstract Heat exchangers with mini- and micro-channel components are capable of high energy exchange due to their incumbent large surface area to volume ratio. Concurrently, recent advances in additive manufacturing simplify the creation of metallic minichannels that incorporate turbulators for heat transfer enhancement. As part of the development of a minichannel heat exchanger with turbulators, this study analyzes the three-dimensional conjugate heat transfer and laminar flow in a minichannel heat exchanger equipped with rectangular winglet vortex generators (VGs) through numerical simulation. The minichannels have a hydraulic diameter of 2.86 mm and are assumed to be made from aluminum alloy AlSi10Mg. This material is one of the popular alloys in the additive manufacturing industry (three-dimensional (3D) printing) because of its light weight and beneficial mechanical and thermal properties. The working fluid is distilled water with temperature-dependent thermal properties. The minichannel is heated by a constant heat flux of 5 W cm−2 and the Reynolds number is varied from 230 to 950. The simulations are performed using the COMSOL® platform, which solves the governing mass, momentum, and energy equations based on the finite element method. The effect of the VG design parameters, which include VG angle of attack, height, length, thickness, longitudinal pitch, and distance from the sidewalls, is investigated. It is found that the generation of three-dimensional vortices caused by the presence of the vortex generators can notably boost the convective heat transfer, at the cost of increased pressure drop, potentially reducing the heat exchanger size for a given heat duty. A sensitivity analysis indicates that the angle of attack, VG height, VG length, and longitudinal pitch have the most significant effects on the heat transfer and flow friction characteristics. In contrast, the VG thickness and distance from the sidewalls only had minor influences on the heat exchanger performance over the studied range of design parameters.
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Nurizki, A., Md Islam, and Md Alam. "Experimental Study of Thermal Performance and Flow Behaviour With Winglets Vortex Generators in a Circular Tube." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4723.
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Abstract Vortex generator (VG) is one of the passive techniques which could improve the heat transfer with relatively low pressure drop. Vortex generators create streamwise longitudinal vortices which does not decay until far downstream that leads to have higher heat transfer with a lower pressure drop. The objectives of this experiment were to study the heat transfer and flow characteristics of fully developed turbulent flow due to different arrangement of VGs in a tube. The experiments were performed by using delta winglet vortex generators in a 52 mm circular copper tube. The flow regime varied from 6000 to 27000 Reynolds number. Four vortex generators with 45° angle of attack were used inside the circular tube. Different parameters of the VGs studied in this experiment such as lengths (L = 10, 15, and 20 mm) and arrangements (R = 0° to −15°). The results indicate that the length affected friction factor (f) and Nusselt number (Nu) significantly. L20 reached the highest f and Nu. The staggered arrangement concludes a significant drop on friction factor and a significant increase on Nusselt number. Consequently, the thermal performance of all staggered arrangement cases could reach a significant rise compared to the inline arrangement. The oil flow visualization could track down the trace of vortex behind the VG. The inline arrangement showed a strong vortex formed as a result of VG which was related to higher f while the staggered arrangement indicated a weak vortex.
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Agarwal, Ruchika, Sridharan R. Narayanan, Shraman N. Goswami, and Balamurugan Srinivasan. "Numerical Analysis on Axial Compressor Stage Performance With Vortex Generators." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43897.
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The performance of axial flow compressor stage can be improved by minimizing the effects of secondary flow and by avoiding flow separation. At higher blade loading, interaction of tip secondary flow and separated flow on blade surface is more near the tip of the rotor. This results in stall and hence decreases compressor performance. A previous study [1] was carried out to improve the performance of a rotating row of blades with the help of Vortex Generators (VGs) and considerable effects were observed. The current investigation is carried out to find out the effect of Vortex Generator (VG) on the performance of a compressor stage. NASA Rotor 37 with NASA Stator 37 (stage) is used as a test case for the current numerical investigation. VGs are placed at different chord wise as well as span wise locations. A mesh sensitivity study has been done so that simulation result is mesh independent. The results of numerical simulation with different geometrical forms and locations of VGs are presented in this paper. The investigation includes a description of the secondary flow effect and separation zone in compressor stage based on numerical as well as experimental results of NASA Rotor 37 with Stator 37 (without VG). It is also observed that the shape and location of the VG impacts the end wall cross flow and flow deflection [1], which result in enhanced stall range.
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Dong, Zulong, Badih Jawad, Liping Liu, and Hossam Metwally. "Vortex Generator Designs to Improve Flow for a Vehicle Side-View Mirror." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10669.
Full textAbstract:
Abstract The unsteady airflow over automotive side-view mirrors is a typical source of turbulence which creates extra drag force, aerodynamic noise and vibration. A CFD analysis is presented for vortex generators (VGs) application on the vehicle side-view mirrors for the purpose of flow improvement. Vortex generators are used to delay flow separation and increase the control surfaces which affect the drag force and down force of the vehicle. Reduced drag force can potentially increase fuel economy, and an increased downforce will increase vehicle grip force and improve vehicle stability which is essential for racing cars. This paper presents practical solutions for mitigating flow turbulence and adjusting down force for existing side-view mirrors. Four VG configurations were designed and numerically analyzed in combination with the baseline model at air speeds ranged from 15 to 80 miles per hour. This research investigated the effect of each VG configuration on the side-view mirror’s aerodynamic performance. The turbulent flow through the side-view mirror were analyzed by using standard K-epsilon (K-ε) Reynolds-averaged Navier-Stokes method. The drag and down forces results were obtained and compared with the baseline model. The CFD analysis concluded the following: (1) Setting the VGs with a 5 degree attack angle on the upwind face of the mirror slightly reduced the drag force. (2) Setting the VGs at the top of the mirror surface greatly increased the downforce with a large drag force increase.
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Manolesos, Marinos, Giorgos Papadakis, and Spyros G. Voutsinas. "On the Application of the Bay Model for Vortex Generator Flows." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75217.
Full textAbstract:
Today, Vortex Generators (VGs) are becoming an integral part of a Wind Turbine blade design. However, the challenges that are involved in the computation of the flow around VGs are yet to be dealt with in a satisfactory manner. A large number of VG models for flow solvers have been proposed and among them, the BAY model is one of the most popular for its ease of use and relatively low requirements for user input. In the present paper, a thorough investigation on the performance and application of the BAY model for aerodynamic Vortex Generator flows is presented. A Fully Resolved Reynolds Averaged Navier Stokes simulation is validated against experiments and then used as the benchmark for the BAY model simulations. The Benchmark case is the flow past a wind turbine airfoil at Reynolds number 0.87e6. When the grid related errors are excluded, it is found that in the model simulations, the generated vortices are weaker than in the fully resolved computation. The latter finding is linked to an inherent deficiency of the model, which is explained in detail. As the vortex generation mechanism is different between the fully resolved and the BAY model simulation, so is the vortex evolution and interaction, even on the same numerical mesh. With regards to grid dependence, the integral BAY force depends on both grid density and grid architecture.