An Approach for the Analysis of Collapse Onset in Elastic Tube Flows

Abstract

An experimental study conducted for the determination of the onset of collapse of an elastic tube of a Starling resistor conveying air is presented herein. The collapse was induced under the action of external pressure p e applied to the tube walls. The influence of length L, thickness h, and modulus of elasticity E of the tube on collapse were determined by using a variety of silicone rubber and latex-Penrose tubes. The experiments were conducted under the presence of constant upstream head with the absence of a longitudinal strain of the tube in a range of flow Reynolds number (Re) 16750 < Re < 70280. At each air flow rate Q through the tube, p e was increased gradually. The inlet and exit pressures of the tubes p 1 and p 2 were measured. The variation of Q with p e was used to determine the onset of collapse. The magnitude of p e at the onset of collapse was defined as p e,c. The visually observed collapse was associated with a flow rate reduction, followed by so-called oscillating and non-oscillating cases. The experimental data at the onset of collapse were expressed in terms of a correlation between Re (h/L) and a non-dimensional pressure parameter defined as (p e,c − p 2)/K p including circumferential bending stiffness of the tube K p.