Pulse Frequency Effect on the Flow Structure and Heat Transfer in an Impinging Gas-Saturated Turbulent Jet

Abstract

The turbulent flow structure and the heat transfer in an unsteady bubbly round impinging jet is numerically simulated for different pulse frequencies. The mathematical model is based on the Eulerian approach for describing the flow dynamics and heat transfer in the disperse phase (air bubbles). The problem is considered in the axisymmetric formulation; the system of unsteady Reynolds-averaged Navier—Stokes equations is solved. The turbulence of the carrier phase (liquid) is described invoking the model of the transport of the Reynolds stress components with account for the bubble effect on turbulence production. The pulse supply frequency effect on the flow structure and the heat transfer in an impinging gas-liquid jet is investigated. The pulsed nature of the jet causes both a considerable (almost twofold) increase in the liquid turbulence and heat transfer during the pulse interval and a considerable suppression of these parameters, when the jet is flow-off, as compared with the case of a steady impinging bubblyjet at the same time-average jet flow fluid rate.