Influence of the mass flow rate and void fraction on the vibration of a horizontal U-bend subjected to an upwards flowing air/water-mixture

U-bends are a common geometry in heat exchangers. In this paper, a U-bend is considered with horizontal straight pipes subjected to an initially stratified water/air flow which moves upwards against gravity. The flow is analyzed with an Unsteady Reynolds-Averaged Navier- Stokes Volume-Of-Fluid approach. For low mass flow rates, large gas bubbles are naturally formed at the entrance of the bend. The transient force on the tube allows to determine precisely the moments of bubble initiation and thus to quantify the bubble frequency. Firstly, the tube is assumed to be rigid and the dependence of force oscillation on the inlet conditions is investigated. Secondly, a Fluid-Structure Interaction calculation is applied in order to determine the vibration amplitude of the tube.

Jaar van publicatie:2018

Toegankelijkheid:Closed