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

Arkady Vladimirovich Seryakov

doi:10.4236/jhepgc.2019.51013

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.

Highlights

Experimental results on the diethyl ether condensate film thickness measurements depending on the heat power value, entering to the heat pipes (HP’s) evaporator are shown in Figure 7 [7] [8] [9]
If the toroidal rotation direction of the vapour vortex due to the Coanda effect occurs from the periphery to the longitudinal axis of the HP’s vapour channel as shown in Figure 2, the vortex due to the surface friction slow down the diethyl ether film moving to the periphery, and its thickness δf in the near-axis area on the HP’s upper cover will have inflated values
The origin of the coordinate system is placed at the junction central axis of the vapour channel with a HP’s flat cover, the z coordinate is measured in the opposite direction to the vapour jet direction

Summary

Introduction

Heat pipes (HP’s) are very interesting heat transfer devices, currently widely used in almost all cases of heat-stressed cooling of spacecraft and satellites, mili-. Together with the wide practical application, the HP’s are of great interest for the scientific study of moist vapour currents, the occurrence of pulsations in the vapour channel during the intermittent vaporization operation of the capillary-porous evaporator, the formation of toroidal vortices near the cooled condensation surface and many other interesting effects [1] [2] [3]. The numerical analysis of the vapour flows in the profiled vapour channel shows the occurrence of toroidal vortex formations near the cooled HP’s surface [7] [8] These vapour vortices are of great interest because their toroidal rotation direction depends on the thermal power entering the HP’s evaporator and affects the thickness of the condensate film of the working fluid.

Experimental Results

Numerical Modeling Results

Analytical Results

Conclusions