PIV experimental investigation of the outflow temperature from nonlinearly stratified reservoir regulated by floating intake

Abstract

Floating intake is an effective facility of selective withdrawal to regulate the outflow temperature from thermally stratified reservoirs. The outflow temperature was the result of the interaction among temperature field, flow field and artificial regulation.To characterize them, three influencing factors (i.e., temperature distribution, outflow rate and submerged depth) were chosen. Experiments were conducted to investigate the response of outflow temperature to influencing factors in a nonlinearly stratified fluid with the particle image velocimetry (PIV) technique. Results showed that the withdrawal layer was formed near the level of floating intake inhibited by the density gradient, and its thickness was proportional to stratification intensity. The withdrawal layer ascended with the decrease in submerged depth, and the thickness also changed due to the variation in density gradient. Although the outflow temperature increased, the variation amplitude depended on the temperature gradient between the two submerged depths. However, enlarging the outflow rate within a certain range had relatively small influence on the withdrawal layer thickness and the outflow temperature. Considering the experimental results, a formula was developed for predicting the outflow temperature based on dimensional analysis and energy conservation.