分层水环境人工诱导内波的强化混合效果

Enhanced mixing by artificially induced internal waves in stratified water environments

针对目前国内外缺乏对内波和水流上涌对水体混合的相对强弱关系研究的现状,采用近似计算的方法,提出了一种区分内波和水流上涌对水体混合所做贡献的新方法,定量计算了内波和水流上涌对水体混合的贡献率.在温度梯度、跃温层厚度、曝气器出水口位置均相同的条件下,当曝气强度从62.5L/(h·m^3)增加到125L/(h·m^3)时,内波对水体混合的贡献从82%降到了50%;在温度梯度、曝气强度、曝气器出水口位置均相同的条件下,随着跃温层厚度的增加,内波对水体混合的贡献从78.5%增加到83.5%.无消波装置的水体混合的有效功率比有消波装置的水体混合有效功率增加了40%以上,影响内波混合最根本的原因是所形成内波的A/T.实验证明内波只需要很少的能量就具有强大的混合作用,而曝气产生的循环水流的混合作用却截然相反,即内波混合具有较高的能量利用率,利用内波破坏水库水体分层和改善水源水质具有广阔的应用前景.

Aiming at the present status of lacking the study on the relative strength between internal waves and water upwelling around the world,a new method of approximate calculation was proposed to calculate the relative contribution to mixing by the internal waves and water upwelling under various conditions.At the same conditions of temperature gradient,thickness of the thermocline and aerator outlet position,when the aeration flow rate increased from62.5L/(h?m3)to125L/(h?m3),the contribution rate of the internal waves to the artificial mixing dropped from82%to50%.At the same conditions of temperature gradient,aeration rate and aerator outlet position,with the increase of thermocline thickness,the contribution rate of the internal waves to the artificial mixing increased from78.5%to83.5%.Compared with the cases without the wave dissipation device,the effective power rates for mixing were increased by more than40%.A/T is the most fundamental factor which influences the mixing by the internal waves.Experimental results indicate that the internal waves only require very little energy to induce strong mixing,which is totally different to that of water upwelling induced by aeration,namely the mixing by internal waves was more efficient in energy consumption.There are broad prospects of applying the internal waves to destroy stratification and to improve water quality in stratified source water reservoirs.