具有空化与通气效应的双曲率试件高速水上迫降
High-speed ditching of double curvature specimens with cavitation and ventilation
AI总结：
本文实验研究三种双曲率机身试件在高速入水时的压力、载荷及空化通气规律，揭示曲率、俯仰角和速度的影响，并评估平板载荷缩放与几何相交面积的适用性。
摘要：
本文通过实验研究了双曲率试件在高水平速度下的入水过程，该试件再现了飞机水上迫降期间首先与水接触的机身后部。研究分析了代表不同飞机类型的三种形状。研究进行了压力和载荷测量，并辅以水下高速可视化。在保持垂直速度与水平速度之比恒定的同时，分析了不同水平速度、俯仰角和曲率的影响。观察结果表明，纵向曲率在水动力学中发挥重要作用，在高速条件下可能导致试件后部出现空化和通气。横向曲率会影响前部和后部的压力与载荷，因为较小的横向曲率会增加流体从侧面逸出的可能性。俯仰角增大会导致载荷在幅值和分布两方面均增加。最后，水平速度提高会使前部载荷更高，同时也会影响后部的空化和通气形态。平板的载荷缩放规律在这些试件的前部仍然适用，但空化和通气的出现使其在后部失效。研究通过先进图像处理技术和压力数据分析，考察了空化区域与湿区面积随时间的演化。将其与试件和静止水面的几何相交面积进行比较，进一步揭示了入水过程中的水动力学现象。
英文摘要：
The water entry at high horizontal speed of double-curvature specimens, reproducing the rear part of the fuselage that first gets in contact with the water during aircraft ditching, is investigated experimentally. Three shapes are analysed, representing different aircraft types. Pressure and load measurements are taken, supported by underwater high-speed visualization. The effects of different horizontal speeds, pitch angles, and curvatures are analysed, while keeping a constant vertical-to-horizontal velocity ratio. It is observed that the longitudinal curvature plays a significant role in the hydrodynamics, potentially leading to cavitation and ventilation in the rear part of the specimen at high speeds. The transverse curvature affects the pressures and loads both at the front and at the rear, since a lower transverse curvature increases the possibility of the fluid to escape from the sides. An increase in pitch angle results in an increased loading, in terms of both amplitude and distribution. Finally, an increased horizontal speed leads to higher loads at the front but also affects the cavitation and ventilation modalities at the rear. The load scaling for flat plates also applies to these specimens at the front, but the occurrence of cavitation and ventilation invalidates it at the rear. The time evolution of the cavitation region and of the wetted area are examined through advanced image processing techniques and pressure data analysis. The comparison with the geometric intersection area of the specimen with the still water surface provides further insight into the hydrodynamic phenomena during the water entry.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
