Abstract: Selective withdrawal is widely implemented to moderate the effect of thermal stratification in large reservoirs and to solve the problem caused by the changes of hydrodynamic and thermal characteristics after the construction of dam. An experimental study was conducted to investigate the temperature and flow fields in front of the temperature-control curtain (TCC) set in thermal structure for selective withdrawal. Impacts of hot-cold water flow ratio, distance from the curtain to water intake, water intake position and water retaining proportion were systematically investigated in the experiments. Outflow temperature was also measured. The results indicated that thermocline thickness upstream side of TCC decreased while thermocline intensified, thus inhibiting water mixing. The thermocline thickness increased obviously, and the vertical diffusion of water was promoted downstream of TCC. When hot-cold water flow ratio, height of water intake and water retaining proportion reduced, the thickness of thermocline increased while the intensity of thermocline attenuated. In addition, the outflow temperature climbed with the augments of hot-cold water flow ratio, position of water intake and water retaining proportion.

Key words: water temperature stratification, temperature control curtain, selective withdrawal, thermocline, outflow temperature