VISUALIZATION AND CHARACTERIZATION OF A LATERAL SWIRL FLOW STRUCTURE IN SINUSOIDAL CORRUGATED-PLATE CHANNELS

摘要

Curved surfaces interacting with fluid flow tend to produce swirl or secondary circulation, and such mechanisms in wavy-plate-fin channels have been investigated. The fluid recirculation or vortex structure in low Reynolds number flows in plate channels with sinusoidal corrugations is characterized by experimental flow visualization and Laser Doppler Velocimetry (LDV) measure-ments. The parametric effects of the wavy-plate geometry, described by its waviness aspect ratio γ (= 2 × amplitude/wavelength) and inter-plate spacing ratio ε (= spacing/2 × amplitude), are delineated. Wall-curvature-induced swirl is produced by fluid separation downstream of the wavy-surface peak, its reattachment upstream of the subsequent peak, and the consequent encap-sulation of lateral recirculating cells in the channel-wall concavities. The characteristic signature of these trough-region vortices is significantly altered with increasing flow rate, inter-plate spac-ing ε, and severity of wall waviness γ, when the swirl tends to grow spatially and envelop much of the core-flow region.