Velocity measurements using UDV in rotating annulus subjected to quasi 2D temperature variations

Abstract

An experimental study was carried on in a rotating cylindrical annulus having temperature variation along both radial and vertical directions. The experiment set up comprises with an inner cylinder which is kept at cold temperature, outer cylinder and a bottom plate where heating is provided along periphery. This inner cooling and peripheral heating represent poles and equator respectively. This enables study on baroclinic instability in laboratory to have better understanding of effect of rotation on heat transport and turbulent convection in atmosphere. In this experiment, UDV (Ultrasonic Doppler Velocimeter) which works on Doppler principle was used to find velocity along the centre axis of cylinder (Z axis) and azimuthal velocity (Y axis). This study was carried out by providing different angular speed i.e. 8.46rpm, 12.9rpm and 17.34 rpm by using a VFD (variable frequency device) to table on which concentric cylinder are placed. By using 2D UDV, velocities at different vertical points were captured. By conducting this experiment it was found that fluctuation in velocity increases in z axis whereas it decrease in Y axis.