Numerical modelling of the flow patterns induced by a push-pull ventilation system

Abstract

Open surface tanks used in industrial processes often need ventilating to remove harmful pollutants from the working environment. One method which can be used is the so-called push-pull ventilation system, in which a jet of air is blown (or pushed) from one side of the tank and collected (or pulled) by an exhaust hood on the opposite parallel side. Such systems can reduce the ventilation air flow requirements by up to 50%. In order to be able subsequently to examine the movement of pollutant around the system, we first need to understand the fluid flow patterns which are generated, and these are examined in this paper. The system is modelled using a commercial computational fluid dynamics package and the results compare favourably with the available experimental data. The geometry of the situation can lead to excessive computational time and so appropriate approximations to reduce the CPU time and simplify the problem are introduced and evaluated.