Paper 23: A Study of the Effect of Space Variable Heat Release on Fluid Flow in a Duct

Abstract

A theoretical and experimental investigation into the effect of non-uniform heating on low-speed fluid flow is reported here. In the theoretical analysis the three-dimensional behaviour of an inviscid, compressible fluid is predicted and a simple expression for the displacement of a streamline is derived. The quasi-two-dimensional flow of air through a rectangular duct, subject to non-uniform heating, is examined and streamline deflections are calculated for various types of flow.

Experiments are described in which air flowing through a rectangular duct is subject to a heat flux which varies across the direction of flow. The characteristics of the flow are determined from flow-visualization observations and from measurements of the mass-velocity distribution upstream and downstream of the heated section.

The experimental results indicate that streamline deflections may be produced by non-uniform heating. The magnitude of the results showed reasonable agreement with those predicted for the ducted flow of air in the turbulent region, but were generally smaller than those based on the inviscid flow of a compressible fluid. The simplified results of a previous analysis for small heat inputs (1)‡ were shown to be applicable when the total heat added was less than 5 per cent of the initial enthalpy of the flow.