Optical Methods for Data Processing in Heat and Fluid Flow

13

A Study of the Flow Structure in the Near-wall Region of a Complex-shaped Channel using Liquid Crystals

G M Zharkova, V N Kovrizhina, and V M Khachaturyan

Abstract

In the present work, results are reported of a study of the structure of a forced convective flow in a complex-shaped channel performed using cholesteric liquid crystals (LC). The model under study was a channel formed by two corrugated surfaces pressed closely together. To measure the temperature fields on the model surface, a thermochromic LC coating was used. To visualize the shear-stress distribution over the model surface the texture transition method based on the use of LC insensitive to temperature was used. The obtained data permit reconstruction of the vortex flow pattern in the near-wall region.

13.1 Introduction

The problem of heat-transfer intensification in various apparatus is a most important one from a practical viewpoint (1, 2). To make a proper choice of the method for raising the heat-transfer rate (or that of the configuration of the heat-exchanging surface for a particular application), it is necessary to possess exact information as to the flow structure and conditions in the channel. In many cases, most suitable surfaces have an intricate shape for which analytical design is impossible. The complexity and great diversity of the possible shape of heat-exchanging surfaces and channels formed by these surfaces require direct experimental studies of the flow structure in such channels to be carried ...