Laminar Flow Development Downstream of an Abrupt Circular Channel Expansion

Abstract

<p>This dissertation reports the development of a flow visualisation technique which was used to study the flow pattern generated by an abrupt expansion in a circular section conduit, Experiments were performed at Reynolds numbers (based on upstream tube diameter) ranging from 222 to 755 and for tube diameter ratios of 0.63, 0.79 and 0.93.</p> <p>Velocity profiles were obtained at each of two different stations beyond the vortex and these were used as upstream boundary conditions for the linearized axial Navier-Stokes equation for the purpose of predicting development lengths. A correlation was obtained for development length as follows:</p> <p>L/D = 0.27 Re⁰˙⁹⁴, D [1- (d/D)²˙⁷⁷] Measurements of vortex length were made for a tube diameter ratio of 0.63 and the results correlated in the form</p> <p>xR/h = 0.048 Re¹˙¹ d</p> <p>Hence both vortex length and development length increase almost linearly with Reynolds number.</p>