Measurement of Joule-heating flow convection induced by internal heat generation using ultrasound velocity profiler in glycerin fluid

Abstract

Joule-heating flow behavior in a square cavity was experimentally investigated by means of Ultrasonic Velocity Profiler (UVP). Two electrode plates are placed on opposing side walls and connected a constant AC voltage. Chaotic unstable flow occurs in the square cavity which was volumetrically heated, mainly by electric current as Joule-heating while top surface was cooling by constant temperature. Besides, the other walls are under adiabatic condition. The quantitative investigation of chaotic flow was become more difficult with increasing the internal heat source. Thus, an ultrasonic velocity profiling method was used to observe chaotic flow by giving the spatiotemporal flow pattern. UVP method was appropriated for this kind of flow because of its capability for opaque flow and instantaneous velocity profile measurement. The spatiotemporal behavior of chaotic flow in a cubic Joule-heating cavity was observed as a temporal variation of the velocity profile. The accurate of UVP measurement system was confirmed with PIV (Particle Image Velocimetry) method for the two-dimension of velocity distribution. As a result, the comparison of vertical velocity profile between UVP and PIV method presents less than 5% error. The Joule-heating flow was observed continuously when electrodes connected with AC voltage. The chaotic level with increasing the internal heat source was investigated quantitatively by analyzing the fluctuation frequency of velocity using Fast Fourier Transform (FFT).