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冰凌下潜是冰塞形成和发展的基础,控制冰凌的下潜对于保证输水工程的安全和输水能力有重要的意义。本文采用VOF方法追踪自由水面,结合RNGk-ε紊流模型,对浮冰块底面水压差分布进行了数值模拟。通过与Dow Ambtmand的物理模型试验数据的对比,验证了该数值模拟方法的合理性和可靠性。基于冰块底面的水压差分布特征,分析冰块的下潜力矩Mu,研究冰凌下潜的临界条件。发现冰块下潜的临界条件涉及到冰块前缘形状和由冰块厚度(δ)、长度(L)与冰块上游水深(H)构成的特征几何尺寸(δ/H、δ/L):同条件下前缘矩形断面冰块较前缘圆形断面冰块易下潜;δ/L一定时,δ/H越大,冰凌下潜临界冰厚弗劳德数Ftcr越小,临界水流弗劳德数Frcr越大;δ/H一定时,δ/L越大,则Ftcr和Frcr均越小。根据数值模拟和力矩平衡分析的研究结果,提出了天然冰凌下潜的判断准则。
Icy ice diving is the formation and development of the basis for the ice, the control of the ice dive for ensuring the safety of water transport and water transport capacity is of great significance. In this paper, the VOF method is used to track the free water surface. The RNGk-ε turbulence model is used to simulate the water pressure distribution on the bottom of the ice floe. The comparison with the physical model test data of Dow Ambtmand verifies the rationality and reliability of the numerical simulation method. Based on the distribution of water pressure difference at the bottom of the ice, the ice’s mulling moment Mu is analyzed to study the critical condition of the ice diving. It is found that the critical condition of ice submergence relates to the shape of ice front and the geometric features (δ / H, δ / L) of ice thickness (δ), length (L) and water depth (H) : Under the same conditions, the front edge of the rectangular section of the ice easier to dive than the front edge of the circular section of the ice; δ / L a certain, δ / H the greater ice ice submerged critical ice thickness Ftcr the smaller the critical flow Froude number Frcr greater; δ / H a certain time, δ / L the larger, then Ftcr and Frcr are smaller. According to the results of numerical simulation and moment balance analysis, the judgment criterion of natural ice diving is proposed.