Numerical Modeling of the Vapour Vortex Formation in the Short Heat Pipes

Abstract

The results of the numerical studies of vortex formation inside short heat pipes (HP's) with profiled vapour channel in the Laval-liked nozzle form are presented. For the first time, it was found that the vapour vortex of moist compressible vapour flow in the cooled part of vapour channel changes its rotational motion direction. The rotation direction of the toroidal vapour vortex, obtained by solving the Navier Stokes equations is dependent on the heat power value, entering to the HP's evaporator. With low heat power loads the rotational direction of the circular toroidal vapour ring due to the Coanda effect and sticking moving vapour jets to the channel's walls occurs from the periphery to the longitudinal axis of the vapour channel. While the heat power load increasing, the direction of the circular toroidal vapour ring rotation changes to the opposite, from the longitudinal axis to the periphery of the vapour channel. The thickness of the formed working fluid condensate film located under the toroidal vapour vortex also related to the evaporator heat power load and the associated toroidal vapour vortex rotation direction. The numerical thickness calculation of the formed working fluid condensate film located under the toroidal vapour vortex was compared with experimental values, obtained by capacitive sensors. The thickness values of the calculated condensate film thickness and experimentally measured values using capacitive sensors are close in magnitude order.