Calculation of a twisted gaseous screen in a cylindrical channel

Abstract

The effectiveness of a twisted gaseous screen in a cylindrical channel and heat and mass transfer under such conditions were studied experimentally in [1-3], where a number of characteristic features, as compared with the nontwisted screen, determined by the rotation of the peripheral part of the flow were established. In particular, it is shown in [i] that increasing the injection parameter of the inert gas m = PsWs/p0w0 in the presence of twisting, unlike the nontwisted screen, intensifies the mass transfer processes. At the same time, flows with partial peripheral twisting differ from completely twisted flows. The main difference consists of the fact that in the presence of peripheral twisting of the flow a typical jet circulation profile with two characteristic zones the zone near the wall and an exterior zone develops. In the part of the circulation profile near the wall (y 0) and the turbulent transport by centrifugal forces is suppressed, which can reduce heat flows from the core of the flow to the wall [i]. This phenomenon is widely employed for thermal shielding of walls and stabilization of arcs in plasma reactors [5]. So, the magnitude of the heat flux in channels with peripheral twisting is determined primarily by two factors intensification of heat transfer in the pare of the boundary layer near the wall and suppression of the external part in it. C0rrespondingly, depending on the specific conditions, the rotation of the peripheral flow can both increase and decrease the coefficients Of turbulent heat and mass transfer on the surface of the channel.