Abstract
The study of unsteady aerodynamic phenomena in wind tunnels is supported by gust-generating devices capable of generating adjustable magnitude and periodicity velocity fluctuations in a flowfield. Gusts are typically generated actively by introducing moving vanes to direct the flow, or passively by tailoring the boundary layer growth and shape in the tunnel. The flow facility used here is a student-built closed-return low-speed wind tunnel, with a test section size of 750 mm × 750 mm and a maximum speed of 25 m/s. A two-vane gust generator utilizing NACA0018 airfoil sections of 150 mm chord length was designed and installed upstream of the test section. The flowfield was mapped with the installed vanes with and without gust actuation, utilizing a hot wire system. The tunnel with gust vanes exhibits a spatially uniform baseline turbulence intensity of 5%, with a steady state velocity deficit of 1 m/s in the vane–wake region. Upon introducing the gusting conditions at vane deflection angles of up to ±45°, velocity differences of up to 4 m/s were attained at 18 m/s freestream velocity at oscillation frequencies ranging between 1 Hz and 2 Hz.
Highlights
Gust generators have been widely used to study the unsteady aerodynamic effects of atmospheric flows by modeling natural wind turbulence [1,2]. They constitute important instruments in a wide range of applications that range from the experimental exploration of gusts on uncrewed aerial vehicles (UAV’s) [3,4], to gust responses of high aspect ratio wings [5,6], to high speed vehicle environmental effects [7], and atmospheric and building related flows [8,9]
Gust generation is the unsteady modification of the boundary conditions at the inlet, tunnel test section walls, or on the model of interest [10]
The tandem oscillating vane generator [13] and Makita active grid [12] are the only gust generators capable of producing atmospheric turbulence conditions, as well as large wind gusts used for aerodynamic model testing
Summary
Gust generators have been widely used to study the unsteady aerodynamic effects of atmospheric flows by modeling natural wind turbulence [1,2]. Gust generation is the unsteady modification of the boundary conditions at the inlet, tunnel test section walls, or on the model of interest [10] This can be achieved either by a passive method or by the active deflection of aerodynamic surfaces in the flow [11]. The tandem oscillating vane generator [13] and Makita active grid [12] are the only gust generators capable of producing atmospheric turbulence conditions, as well as large wind gusts used for aerodynamic model testing. A power spectrum plot of the observed frequencies closes the results section, followed by overall conclusions
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