基于相似理论的海洋温跃层模拟水池研究

为模拟海洋温跃层环境,检验所设计的水下热滑翔机在温跃层中的水动力性能,根据相似理论分析了温度梯度为0.2℃/m及水深10 m以下的海洋温跃层模拟水池的各项特征:缩尺比、水池主尺度、温度场和动力相似数。采用数值计算和理论计算方法,预测了设计水池中的待试模型与实体水下热滑翔机的阻力,并对二者进行比较,验证了所设计的水池模拟的水动力效果。以传感器阵列测量水池的温度梯度,验证了温度场相似的设计目标。通过研究和试验,验证了海洋温跃层模拟水池的可行性和可靠性。研究表明:用于水下热滑翔机水动力及相变性能研究的海洋温跃层模拟水池,其水流温度梯度需为实际温跃层温度梯度的缩尺比的平方倍;模拟海洋温跃层的室内水池通过选取合理的几何尺寸,可以抑制阻塞效应、浅水效应及池壁效应的不良影响。

A Design for Ocean Thermocline Simulation Pool Based on the Similarity Theory

In order to simulate the thermocline characteristics of ocean environment and investigate the hydrodynamic performance of an underwater thermal glider navigating within, various characteristics of the ocean thermocline simulation pool are analyzed in this paper, based on the similarity theory. The pool is first designed to simulate the underwater thermocline layer with a depth no less than 10 meters and a temperature gradient of 0.2 Celsius degrees per meter. The technical parameters of the pool include the scaling factor, principal dimensions, temperature field and dynamical similarity coefficient. Next, the resistances of the glider model tested in the pool and that of the actual glider in the ocean are obtained using a numerical simulation approach and ITTC＇ s experiential formula of drag, respectively. Comparison between the results shows a difference less than 5 percent. Meanwhile, the temperature gradient of the pool is measured with a linear series of temperature sensors. The result also indicates a difference less than 3.5 percent com- pared with real data, which again validates the feasibility and reliability of the pool. It is found out that the temperature gradient ratio of the simulation pool to the ocean thermocline layer should be determined by the square of the scaling factor. Moreover, the adverse effects such as the blocking effect, shallow water effect and side wall effect could be well restrained by choosing an appropriate dimension of the pool.