【作者】 熊永亮；

【导师】 郜冶； 王革；

【作者基本信息】 哈尔滨工程大学 ， 热能工程， 2006， 硕士

【摘要】 当水高速流过物体时，物体表面压力会下降到此时的饱和压力，此时水会低温汽化形成空泡，空泡的产生和溃灭引起的力学效应在工程上会产生很重要的影响。但超空泡的形成对水下航行体减阻具有极其重大的意义。空泡问题带来的强非线性关系使得空泡理论研究的重大突破具有很大难度。文中以描述泡泡的瑞丽方程为起点，合理得出空泡与水之间的质量输运关系，同时用有限容积法求解纳维—斯托克斯方程组与描述湍流的k、ε方程组。由于空泡两相流不满足各向同性假设，很难找到比较适用于这种流动的湍流模型，标准k-ε二方程模型在空泡产生区会过高估计湍流粘性比，因而在计算中改变了原有标准k-ε二方程湍流模型湍流粘性系数的定义，修改后的湍流模型对纯液相和纯汽相与标准k-ε二方程模型一致，对于两相混合区域做了一定的修正。运用所采用方法得出的计算结果与经典实验对比相一致。同时利用动网格技术对某超空泡航行体模型进行仿真，结果证明了超空泡具有很强的减阻特性。对于空泡问题的无量纲数也展开进行了研究，结果表明不同参数变化引起的不同空泡数对流场中空泡的结构有一定的影响。几何外形是引起空泡的一个重要原因，因而文中对三种不同外形的空化器做了研究，结果也反映了它们对空泡有不同影响，另一方面，通过计算中改变航行体的长度发现空化器是引起空泡的主要因素，其后的长度对空泡影响甚微，在空泡数较小时航行体长度对阻力系数的影响较小。更多还原

【Abstract】 The pressures around the objects fall below the saturated vapor pressure at the temperature when the water flows around them. The process of rupturing the liquid by a decrease of pressure at constant temperature is called cavitation. The generation and disappearance of cavity result in important mechanical effects along with the cavity. However, it is very important to decrease the drag force for the submarine vehicle. The nonlinear relation was caused by cavitations which make it too difficult to achieve its analytic solution.A rational relationship of mass transport between water and vapor was concluded on the basis of Rayleigh-Plesset equation. The finite volume method is employed to solve the Navier-Stokes equations and the k , ε equations. For the anisotropy of the multiphase flows, it was hard to find an exact turbulence model. In the cavity zone, turbulence viscosity ratio was over-predicted in standard k-e turbulence model. So an evaluation turbulence model was proposed. In fully cavity zone and pure water zone, the model was in consistent with the standard k-e turbulence model. The turbulent viscosity coefficient in mixing zone was revised in the model. The result by adopted method is in good accord with the experiment data. A simulation of submarine vehicle shows that supercavitation has the good performance in drag reduction. Cavitation number is affected by several variables, each of them affects the flow field differently, and it is necessary to study the influence by each of them. On the other hand, the geometry of vehicle also plays an important role in cavitation multiphase flow. Three kinds of cavitor was simulated in the paper, the result shows that the disk cavitor cause the largest cavity and drag coefficient and the other way round , the cone cavitor cause the smallest cavity and drag coefficient. The simulation result indicated that the length of vehicle was unimportant compared with the cavitor both in cavity zone and drag efficient on the status of supercavitation.更多还原