关键词: 螺旋通道, 涡发生器, 湍流, 流动阻力, 数值模拟

Abstract: Experimental and numerical methods have been employed to study the influence of winglet pair geometry parameters on fluid flow and vortices characteristics in helical channels with semicircular cross section. The curvature ratios of helical channels are within the range of δ=0.05~0.125. Simulated data of three dimensional velocities have good agreements with those obtained by Laser Doppler velocimeter when δ=0.067. The results showed that the longitudinal vortices induced by the wing pair developed spirally along the main flow and strengthened the vortices produced by centrifugal force to a certain extent. The larger the Reynolds number was, the closer of the vortices were to the centerline of the cross section. There may be additional vortices in the range of 7.09~13.04 times of wing height behind the winglet pair when δ≥0.1. The value of La/b was used to indicate the occurrence position of the additional vortices. La/b value increased with the increasing of Reynolds number and the aspect ratio of the winglet, but it decreased with the increasing of curvature ratio and attack angle. As curvature ratio and the aspect ratio of the wing increasing, the strength of the combined longitudinal vortices would be enhanced and the affecting range of combined vortices in the helical channel became larger at the same time. The maximum strength of the combined longitudinal vortices was 6.48 times that of the smooth helical duct in the studied range. The longest affecting range of combined vortices reached the length of about 20 times the wing height in the helical channel. The aspect ratio of the wing and dimensionless thickness had significant impacts on flow resistance.

Key words: helical channel, vortex generator, turbulent flow, flow resistance, numerical simulation