Passive active control of cavitating flows around ship hydrofoils

空化对船舶螺旋桨、方向舵、泵和其他机械的性能产生负面影响，因为它是侵蚀和能源效率损失的主要来源之一。在这方面，空化控制方法可以帮助改进推进和转向装置的设计。被动空化控制方法已成功应用，且成本较低，是较好的选择。然而，对于严重空化情况（例如，海上风力供应船的动态定位），仅使用被动控制方法很难实现云空化的缓解和控制。另一方面，对于不同的空化状态，只使用主动控制方法需要额外的能量，从而导致更高的成本。因此，被动-主动组合控制方法是有效抑制大范围空化和降低成本的首选。为此，主动控制方法仅用于严重的空化状态，而被动控制方法无法控制空化。在这个项目中，我们打算利用放置在水翼表面的微型涡发生器和离散准径向射流（注水）的组合来开发一种被动-主动控制方法。首先，我们将扩展和验证现有的多尺度欧拉-拉格朗日方法，以考虑空化流的可压缩性。其次，我们将使用扩展的多尺度欧拉-拉格朗日方法（基于pans方程）进行系统的数值研究。通过改变微型涡发生器的位置和注入速度，确定了该控制方法的优化配置，以抑制空化并减轻其负面影响。然后，我们将在我们的空化隧道中进行系统的实验调查，使用高速成像，力和压力传感器，水听器以及先进的处理程序和数据分析方法。

Cavitation negatively affects the performance of marine propellers, rudders, pumps, and other machinery as it is one of the major sources of erosion and energy efficiency lost. In this regard, cavitation control methods can help to improve the design of propulsion, and steering devices. Passive cavitation control methods were successfully used and are the preferable choice, because of the low costs. However, the mitigation and control of cloud cavitation for severe cavitation regimes (e.g., dynamic positioning of wind offshore supply vessels) can hardly be achieved using only a passive control methods. On the other hand, using only active control methods for different cavitating regimes requires extra energy and, consequently, leads to higher costs. Therefore, a combined passive-active control methods are the preferred choice to efficiently suppress cavitation for a broad range of cavitation regimes and reduce costs. For this aim, the active control method is only used for the severe cavitation regimes, where the passive control method is not able to control cavitation. In this project, we intend to develop a passive-active control method by using miniature vortex generators placed on the hydrofoil surface and a combination of discrete quasi radial jets (water injection). First, we will extend and validate an existing multi-scale Euler-Lagrange method to take into account compressibility of the cavitating flow. Second, we will perform systematic numerical investigations using the extended multi-scale Euler-Lagrange method (based on PANS-equations). Varying the positions of the miniature vortex generators and the injection rates, the optimized configuration of the proposed control method will be determined to suppress cavitation and mitigate its negative effects. We will then perform systematic experimental investigations in our cavitation tunnel using high-speed imaging, force and pressure sensors, and hydrophones together with advanced processing procedures and data analysis methods.