大型水库帷幕水温分层取水效果研究

Effect of Temperature Control Curtain on Selective Water Withdrawal in Large Reservoirs

为探索减缓已建水库对下游产生的低温水不利影响的新措施,以某已建大型水库为例,开展不同帷幕布设方式对改善下泄低温水效果的研究。采用立面2维数学模型计算某大型水库坝前垂向水温结构及下泄水温过程,设计不同遮挡高度、淹没深度及距坝轴线距离等6个帷幕方案,并对各方案的流场及温度场进行对比分析。结果表明:帷幕设置将显著影响库区的浮力流动及垂向温度分布,3种局部遮挡方案下取水口的抽吸作用导致底层低温水体绕过帷幕被较多地引用,均不能有效提高下泄水温,底部全遮挡方案的设置对提高水库下泄水温效果明显,但同时由于持续取用表层温水,库区水温显著降低。淹没水深应结合取水层厚度确定,当淹没水深与帷幕上层取水层厚度相近时有较好的低温水改善效果。坝前1 km范围内帷幕轴线位置对下泄水温的影响不明显。建议水温控制帷幕的设计采用底部全遮挡,中底部全遮挡帷幕方案的下泄水温5—8月较无措施时分别升高了3.4、2.1、1.1、0.4℃,帷幕提高下泄水温效果明显。

In order to explore new measures to relieve the effects of thermal stratified reservoirs.By taking a built large reservoir as an example,a temperature control curtain was used to improve the effects.Laterally 2-D water temperature model was applied to compute water temperature of vertical stratified reservoir and selective water withdrawal.Six curtain plans were designed which included different height,submerged depth and location of curtain.Water temperature and flow field were also analyzed.The results showed that water temperature profiles and flow field were noticeably influenced by curtain.The bottom water was inhaled more in the 3 partial shield plan,these three plans could not improve temperature of withdrawal.However,bottom full shield plans improved the water temperature obviously,a large amount of surface water was taken,which made the temperature of reservoir reduced evidently.Submerged depth should be determined by the thickness of water intake layer.There would be a better effect when submerged depth was near the thickness of water intake layer.The effect of curtain position on the withdrawal water temperature was not obvious.Compared with no curtain,the water temperature raised 3.4,2.1,1.1,0.4 ℃,respectively between May to August.