西安建筑科技大学学报(自然科学版)

跃温层厚度对内波破坏水体分层特性的影响

(1.西安建筑科技大学西北水资源与环境生态教育部重点实验室,陕西省环境工程重点实验室,陕西西安 710055;2.咸阳陶瓷研究设计院有限公司,陕西咸阳 712000)

Effects of vpycnocline thickness on characteristics of destratification by internal waves

SUN Xin¹,CHEN Xiaohan¹,LIU Xingshe¹, CHENG Zhiwen²,LI Qing²

(1.Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Shaanxi Key Laboratory of Environmental Engineering, Xi'an Univ. of Arch. & Tech., Xi'an 710055 China;2.Xianyang Research & Design Institute of Ceramics, Shaanxi Xianyang 712000, China)

Keywords：internal waves; destratification; pycnocline thickness; wave amplitude; mixing efficiency

DOI: 10.15986j.1006-7930.2019.02.018

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为探求人工诱导内波混合技术在实际大水深分层湖泊水库中的应用效果,采用自主研制的机械混合装置和分层水库物理模型,开展不同跃温层厚度条件下内波破坏分层的中试研究.机械混合装置出流形成水流循环,在水体分层状态下,出流动能转化为内波波能,环流减弱但依旧存在,在内波破坏水体分层过程中,变温层与等温层的水温差别逐渐减小,跃温层逐渐上移且厚度减小,直至水体分层被完全破坏.在跃温层温度梯度、水流扰动强度、水深均相同的条件下,随着跃温层厚度的增加,水体稳定系数增大,临界层内波波能损失减小,内波波幅和能流密度增加,混合效率提高,内波周期不变,波速稍有减小.实验说明内波混合水体技术应用于大水深水体中时将有更高的效率.

To explore the effectiveness of destratification by artificially-induced internal waves in practical deep-water stratified lakes and reservoirs, destratification experiments under different pycnocline thickness conditions were performed with a self-designed mechanical mixing device in a physical model of stratified reservoir. The outflow of the mechanical mixing device formed the flow cycle. When water was stratified, the outflow kinetic energy was converted into the internal wave energy, and the circulation weakened but still existed. In the destratification process by internal waves, the temperature difference between the epilimnion and hypolimnion decreased gradually, and the pycnocline became thin slowly and was impelled upwards until stratified water environment was completely destroyed. Under the same conditions of the temperature gradient of pycnocline, flow disturbance intensity and water depth, as the pycnocline thickness inereases, water stability coefficient increases; wave energy loss in critical layer reduces, the amplitude and wave energy of internal wave increase, the mixing efficiency increases, the internal wave period is constant, and the wave velocity decreases slightly. When applied to practical lakes and reservoirs, the outflow of mechanical mixing device can induce the internal waves to destroy the stratification with higher efficiency.