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An experimental investigation of a NACA 0012 wing-tip vortex flow in a subsonic wind tunnel / Benjamin Gulcu 

Public ISBD Titre : An experimental investigation of a NACA 0012 wing-tip vortex flow in a subsonic wind tunnel Type de document : Travail de fin d'études Auteurs : Benjamin Gulcu, Auteur ; Xiaofeng Liu, ; Laurent Bricteux, Editeur : ECAM Année de publication : 2017 Note générale : University of San Diego Langues : Anglais (eng) Index. décimale : TFE - Electromécanique Résumé : Wing-tip vortex flow, a natural phenomenon occurring at the tip of a finite wing, is important for scientific research and practical applications. When a wing generates lift, the pressure is high at the bottom of the wing and low on top of the wing. As a result, the flow rolls up at the tip of the wing forming the so-called wing-tip vortex. This wing-tip vortex forms the primary component of wing wake turbulence, reducing the wing’s capacity to generate lift, altering the airflow around the tip and generating downwash behind the wing. Furthermore, downwash induces additional drag component, which further increases the amount of fuel consumption of the aircraft. Wing-tip vortex features concentration of vorticity shed from the surface of the wing. This study aims to document the streamwise evolution of the vorticity dynamics and the associated unsteadiness and spectral composition. To this end we design, build and mount a NACA 0012 airfoil, investigating wingtip vortices and analyzing their aerodynamic behavior in a subsonic wind tunnel at San Diego State University. The NACA 0012 airfoil was made by 3D printing and has a chord length of 8 inches, wingspan of 18.5 inches. The wing is mounted vertically in the test section by means of a threaded rod in a rotating plate to set different angles of attack. The San Diego State University Subsonic Wind Tunnel has a test section of 45 inches wide, 32 inches high and 68 inches long. This test section presents viewing windows in Plexiglas on both side walls allowing optical visualization. Experiments are conducted at angles of attack of 4°, 8° and 12°, with corresponding Reynolds numbers of 1.34x?10?^5, 2.69x?10?^5 and 4.04x?10?^5, respectively. To characterize the structure of the vortex wandering phenomenon as well as its frequency and amplitude, we use Stereo-PIV (Particle Image Velocimetry) to measure the velocity distribution and use Hot-Wire Anemometer to investigate the frequency composition in the tip-vortex flow. An experimental investigation of a NACA 0012 wing-tip vortex flow in a subsonic wind tunnel [Travail de fin d'études] / Benjamin Gulcu, Auteur ; Xiaofeng Liu, ; Laurent Bricteux,  . - ECAM, 2017. University of San Diego Langues : Anglais (eng) Index. décimale : TFE - Electromécanique Résumé : Wing-tip vortex flow, a natural phenomenon occurring at the tip of a finite wing, is important for scientific research and practical applications. When a wing generates lift, the pressure is high at the bottom of the wing and low on top of the wing. As a result, the flow rolls up at the tip of the wing forming the so-called wing-tip vortex. This wing-tip vortex forms the primary component of wing wake turbulence, reducing the wing’s capacity to generate lift, altering the airflow around the tip and generating downwash behind the wing. Furthermore, downwash induces additional drag component, which further increases the amount of fuel consumption of the aircraft. Wing-tip vortex features concentration of vorticity shed from the surface of the wing. This study aims to document the streamwise evolution of the vorticity dynamics and the associated unsteadiness and spectral composition. To this end we design, build and mount a NACA 0012 airfoil, investigating wingtip vortices and analyzing their aerodynamic behavior in a subsonic wind tunnel at San Diego State University. The NACA 0012 airfoil was made by 3D printing and has a chord length of 8 inches, wingspan of 18.5 inches. The wing is mounted vertically in the test section by means of a threaded rod in a rotating plate to set different angles of attack. The San Diego State University Subsonic Wind Tunnel has a test section of 45 inches wide, 32 inches high and 68 inches long. This test section presents viewing windows in Plexiglas on both side walls allowing optical visualization. Experiments are conducted at angles of attack of 4°, 8° and 12°, with corresponding Reynolds numbers of 1.34x?10?^5, 2.69x?10?^5 and 4.04x?10?^5, respectively. To characterize the structure of the vortex wandering phenomenon as well as its frequency and amplitude, we use Stereo-PIV (Particle Image Velocimetry) to measure the velocity distribution and use Hot-Wire Anemometer to investigate the frequency composition in the tip-vortex flow.

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Experimental investigation of the horseshoe vortex around the base of a wall-mounted cylinder / Vincent Dhondt 

Public ISBD Titre : Experimental investigation of the horseshoe vortex around the base of a wall-mounted cylinder Type de document : Travail de fin d'études Auteurs : Vincent Dhondt, Auteur ; Xiaofeng Liu, ; Xavier Van den Dooren Editeur : ECAM Année de publication : 2017 Note générale : University of San Diego Langues : Anglais (eng) Index. décimale : TFE - Electromécanique Résumé : This report aims to conduct quantitative experimental investigation of the behavior of the horseshoe vortex which is created when a boundary layer encounters the base of an infinite wall-mounted cylinder. The mechanism of formation of the horseshoe vortex will be analyzed. Additionally, the distribution of the different velocities upstream of the obstacle as well as the location of the separation point compared to the stagnation point will be discussed. The comprehension of the behavior of the horseshoe vortex is important in several engineering applications. For example, the high stress beneath the horseshoe vortex can create erosion around the base of a bridge pier. Flow around a cylinder can also occur in practical situation like in turbomachinery, in an aircraft landing gear or in high rise building. Likewise, the modern measurement technologies allow to obtain accurate results. The cylinder is placed vertically in a wind tunnel and the measurements are made thanks to the stereo – PIV (Particle Image Velocimetry) and the hot – wire anemometer. The diameter of the cylinder (6 inches / 152.4 mm) and the free stream velocity (10 m/s) give a Reynolds Number of ReD=1x105. The test section of the tunnel is 45x32x68 inches (1143x813x1727 mm). A horizontal plate is inserted in the middle of the axis of the cylinder. In this way, the new “base” of the cylinder can be seen by the cameras. This plate has a 3:2 semi-elliptic leading edge, covered by distributed roughness. The goal of this profile is to create a turbulent boundary layer upstream the cylinder. Experimental investigation of the horseshoe vortex around the base of a wall-mounted cylinder [Travail de fin d'études] / Vincent Dhondt, Auteur ; Xiaofeng Liu, ; Xavier Van den Dooren . - ECAM, 2017. University of San Diego Langues : Anglais (eng) Index. décimale : TFE - Electromécanique Résumé : This report aims to conduct quantitative experimental investigation of the behavior of the horseshoe vortex which is created when a boundary layer encounters the base of an infinite wall-mounted cylinder. The mechanism of formation of the horseshoe vortex will be analyzed. Additionally, the distribution of the different velocities upstream of the obstacle as well as the location of the separation point compared to the stagnation point will be discussed. The comprehension of the behavior of the horseshoe vortex is important in several engineering applications. For example, the high stress beneath the horseshoe vortex can create erosion around the base of a bridge pier. Flow around a cylinder can also occur in practical situation like in turbomachinery, in an aircraft landing gear or in high rise building. Likewise, the modern measurement technologies allow to obtain accurate results. The cylinder is placed vertically in a wind tunnel and the measurements are made thanks to the stereo – PIV (Particle Image Velocimetry) and the hot – wire anemometer. The diameter of the cylinder (6 inches / 152.4 mm) and the free stream velocity (10 m/s) give a Reynolds Number of ReD=1x105. The test section of the tunnel is 45x32x68 inches (1143x813x1727 mm). A horizontal plate is inserted in the middle of the axis of the cylinder. In this way, the new “base” of the cylinder can be seen by the cameras. This plate has a 3:2 semi-elliptic leading edge, covered by distributed roughness. The goal of this profile is to create a turbulent boundary layer upstream the cylinder.

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