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Vortex generators configuration (R=vortex generators location, from the leading edge of the airfoil at 10% to 20% of the chord).
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The purpose of this work is to study, in turbulent flow conditions, the effect of tri-angular vortex generators placed on the upper surface of an airfoil, on its aerodynamic coef-ficients. Those vortex generators were used as passive flow control devices. In the experiments, different configurations of those devices have been studied. Their positio...
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Citations
... A new method is used for efficiency improvement and optimisation of Vertical axis wind turbine [14]. Experimental investigation of low Reynolds number aerofoil [15] with vortex generators was performed. NACA 0018 aerofoil was simulated using CFD code [16]. ...
Flow separation causes loss in performance of wind turbine blade. Investigation of S819 aerofoil through passive flow control technique is done using CFD code Fluent. In present work, numerical modelling and simulation of wind turbine blade aerofoil are performed. CFD simulation of S819 aerofoil is performed at various incident angles 0°–30°. To control the flow separation over S819 aerofoil, a new technique with leading edge hole is provided. CFD investigation is done for both types of aerofoil using k − ω turbulent equation. Comparison is made between simple aerofoil and controlled aerofoil where results show delay in flow separation and improvement in lift force at different angle of attacks while reducing the drag force.
... The use of a pair of counterrotating VGs placed at a 30°blade angle on an airfoil at low Re improved the maximum lift coefficient and increased the stall angle (Seshagiri et al., 2009). The different configurations of the VGs located at 10% C and 20% C on the upper surface of the Eppler 387 airfoil led to improved aerodynamic performance (Delnero et al., 2012). The aerodynamic characteristics of NASA's two-dimensional and three-dimensional common research models were studied by Koike et al. (2015) with corotational VGs for multiple intervals and heights. ...
... The use of a pair of counterrotating VGs placed at a 30°blade angle on an airfoil at low Re improved the maximum lift coefficient and increased the stall angle (Seshagiri et al., 2009). The different configurations of the VGs located at 10% C and 20% C on the upper surface of the Eppler 387 airfoil led to improved aerodynamic performance (Delnero et al., 2012). The aerodynamic characteristics of NASA's two-dimensional and three-dimensional common research models were studied by Koike et al. (2015) with corotational VGs for multiple intervals and heights. ...
A numerical investigation was carried out to study the effectiveness of vortex generators on the aerodynamic performance of the NACA 63-215 airfoil. The Reynolds averaged Navier-Stokes (URANS) equations with the SST k-ω Turbulence Model were solved in these simulations to investigate the effects of the vortex generators (VGs) height and length. Two Different configurations of VGs were studied. In the first one, a validation of an experimental study of an airfoil with VGs placed at 10% of the leading edge was carried out. Second a novel configuration was used in which the length and the height of the VGs are increased to enhance the aerodynamic performance. The predicted aerodynamic coefficients agreed well with the experimental results. The results showed that the novel configuration improves the maximum lift coefficient of the NACA 63-215 airfoil with a decrease in the drag coefficient at high angles of attack, in addition, the lift / drag ratio was also increased. Furthermore, the obtained pressure distribution, the velocity contours and streamlines illustrate how the VGs enhance the aerodynamic performance of the NACA 63-215 airfoil.
... Their results revealed that the reasonable combination of a flap and VGs can significantly improve the aerodynamic performance of the airfoil, providing an ideal form of combined control. In 2012, Delnero et al. [28] experimentally investigated the effects of triangular VGs on airfoil aerodynamic performance. The VGs were located 10% and 20% away from the airfoil leading edge. ...
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%.
... Another cause for flow separation is when a bubble stays in the leading edge zone and grows enough to cause a soft stall from flow separation on the trailing edge. All this clearly depends on the Reynolds number and the turbulent flow proper-ties, most influenced by the turbulent intensities and characteristic scales (Delnero et al., 2005(Delnero et al., , 2012. ...
... The tests were conducted in the wind tunnel of the UIDET-LaCLyFA at the National University of La Plata (Delnero et al., 2012). It is a closed-circuit wind tunnel, with a test section of 1.4 m x 1.0 m x 7.5 m and Vmax = 20 m/s. ...
The objective of this study is to experimentally determine the fluid dynamic configuration of the dynamic stall of an airfoil in turbulent flow. Wind tunnel tests were carried out in order to characterize the airfoils behavior in static and static after a quick change in the angle of attack (“dynamic case”) using flow visualization, loads and hot-wire anemometry measurements at different Reynolds numbers and with one rate of change for the angle of attack. In all the tests, a Worthmann FX 63-137 airfoil model was used. First, with the visualizations made using a paint technique, for the different configurations, some differences in the flow pattern were found and points of interest in the airfoil were chosen. In those points, the sensors for the velocity measurements were placed. With the velocities acquired using a hot-wire system, autocorrelations, turbulence intensities, density power spectrums and wavelet maps were calculated and compared between the static and the dynamic case; different results were found and explained. Additionally, differences were traced in the turbulent intensities in the wake of the airfoil. Furthermore, a wavelets analysis was performed, and the flow scales obtained show differences for the same conditions analyzed before.
... En los ensayos mostrados para un cambio brusco en el ángulo de ataque, se observa como existe un patrón de flujo diferente comparando el caso estático con el dinámico (Figura 3 y Figura 4). En dichas figuras se observa claramente una burbuja de recirculación en el borde de ataque para el caso estático, donde este fenómeno es típico en los perfiles de bajo Reynolds a estos números de Reynolds [11], [12], [13]. En el caso del cambio brusco de 10° a 19° la burbuja no se observa y el desprendimiento en el borde de fuga sobre el extradós se encuentra retrasado con respecto al caso estático. ...
RESUMEN El presente trabajo representa la continuación de los trabajos de análisis experimental del efecto conocido como pérdida dinámica sobre un perfil aerodinámico bajo condiciones de flujos turbulentos incidentes. En particular, el perfil ensayado es un Wortmann FX 63-137 utilizado ampliamente en palas de aerogeneradores. El objetivo del trabajo consiste en determinar la configuración fluidodinámica general en la pérdida dinámica del modelo. En trabajos previos se caracterizó el perfil mediante un ensayo de cargas en el túnel de viento de capa límite del LaCLyFA. A partir del ensayo se obtuvieron las curvas características del perfil para diferentes números de Reynolds, obteniéndose parámetros significativos como: C lmáx , ángulo de pérdida, etc. Luego, se implementó un mecanismo neumático para generar cambios bruscos de ángulo de ataque del perfil. Una vez realizado, se procedió a los diferentes ensayos de visualizaciones del flujo para los diferentes Reynolds y diferentes velocidades de cambio de ángulo de ataque. Con la determinación cualitativa de la configuración fluidodinámica realizada en dicho trabajo más las mediciones de anemometría realizadas, se seleccionaron las zonas donde se midieron nuevamente velocidades a través de anemometría de hilo caliente con tres sensores de dos componentes en simultáneo (sobre el perfil y en la estela del mismo). Del análisis de los resultados de los ensayos se observan diferencias en los patrones de flujo resultante, luego de la entrada en pérdida del modelo. Se plantean análisis y discusiones sobre los posibles efectos. Palabras clave: Doble pérdida, FX 63137, visualización doble pérdida, pérdida dinámica.
... Jirásek [14] investigated the vortex generators with various shapes. Delnero et al. [15] investigated the low Reynolds number airfoil with vortex generators experimentally. Seshagiri et al. [16] studied the control effects of steady and unsteady vortex generator on airfoil. ...
A new flow control approach called split blade is applied on the S809 airfoil in the present study. S809 airfoil was investigated experimentally and numerically with different operating conditions including cascade without control, cascade with slots that generate jets with AOAs of 0 degrees, 10 degrees, 15 degrees and 20 degrees. Good agreement was obtained between the comparison of the experimental and numerical results. The results show that the separation area increases with increase of the AOA and the large separation area appears on the airfoil suction surface at AOA equal to 20 degrees. Numerical results show that the control method has little negative influence on the airfoil performance at small AOAs. Smaller vortices are filled with the large separated area which is divided by the jet generated by split when the AOA is 20 degrees. The analysis on the lift coefficient and drag coefficient shows that the flow is improved with the control. The lift coefficient and drag coefficient do not change in the comparison between the cases before and after control when AOA is 0 degrees and 10 degrees. However, the lift coefficient increases and drag coefficient decreases when AOA is 15 degrees and 20 degrees.
Two-wheeler vehicles are having challenges in adopting advanced after-treatment devices due to their compactness and lightweight. Swirl and tumble motion inside the cylinder is considered to be the desired way to improve combustion efficiency and reduce engine emissions. The present study investigates the effect of swirl and tumble motion on combustion characteristics of gasoline–methanol blend in the SI engine. This study presents a new approach to calculate the motion of the flow, including swirl and tumble during both the intake and the compression strokes using 3D-CFD simulation. The effects of the swirl and tumble variations were evaluated in terms of the swirl and tumble ratios, the turbulent kinetic energy, and the vortex motion characteristics at intake valve closing (IVC). The numerical simulations are conducted at different engine speed, and the effect of engine speeds on the in-cylinder fluid motions are analyzed and presented. Four different methanol–gasoline blends (M05, M10, M15, and M20) are used to investigate the effect of different blends on engine performance and emission. A model of 2D cylinder piston cavity is used for combustion simulation at different speeds of the engine for different swirl and tumble ratios. It was found that the swirl and tumble ratios mainly vary with the position of crank angle. The cylinder pressure increases with the increase in methanol percentage. Additionally, the turbulent kinetic energy increases with the increase of speed and swirl and tumble ratio, which leads to the completeness of combustion and improves the performance of the engine.
