旋成体高速入水可压缩性影响研究

针对目前高速（≥100 m/s）跨水-气体界面多相流数值模拟中空化效应和水介质可压缩性影响等问题，建立一套高速入水数值模拟方法。以旋成体为计算模型，采用剪应力传递(SST) k-ω、 标准(Standard)k-ε、重整化群(RNG)k-ε及可实现(Realizable) k-ε 4种湍流模型进行数值模拟，得到速度衰减与入水深度随时间变化的结果及入水1 ms时的空泡形态，并与理论解比较。基于SST k-ω湍流模型与文献［15，17］实验开展对比研究，选取入水速度50 m/s、100 m/s、200 m/s、400 m/s、800 m/s进行计算。研究结果表明：采用SST k-ω湍流模型的数值模拟结果与理论解一致性最好，入水速度衰减、空泡发展与实验结果基本一致，证明该方法的有效性；在入水速度≤100 m/s时， 液体可压缩性对入水冲击载荷基本没有影响；在入水速度≥200 m/s时，随着入水速度增加，液体可压缩性对入水冲击载荷影响越大，会弱化入水冲击载荷及延缓最大载荷出现的时间；在考虑液体可压缩性时，空泡形态有收缩现象；入水速度越大，入水过程速度衰减越快，加速度值在入水初期较大；在计算模型周围被超空泡包裹的航行阶段，随着入水深度增加，加速度逐渐减小，加速度的变化逐渐平缓。

Effect of Fluid Compressibility on High-speed Water-entry of Revolutionary Body

A set of simulation methods for high-speed (≥100 m/s) water-entry is developed for both cavitation and compressible effects in the numerical simulation of multi-phase flow at water-air interface. The revolutionary body is used as a computing model, and the turbulence models, including SST k-ω, Standard k-ε, RNG k-ε, and Realizable k-ε, are utilized for simulation. The change results of velocity damping and water-entry depth with time are obtained. The cavitation configuration at 1 ms is outlined. The simulated results are compared with the theoretical solutions, and the simulated results by SST k-ω agree with the theoretical solutions. The set of methods is used for the reference experiments in Refs. ［15］ and ［17］. Compared with experimental results, the set of methods is validated in terms of velocity damping and cavitation development. Some different water-entry velocities, including 50 m/s, 100 m/s, 200 m/s, 400 m/s and 800 m/s, are regarded as initial condition to be computed. The compressibility of water has no effect on the water-entry impact basically when water-entry velocity is less than 100 m/s. Beyond that, the compressibility of water has much effect on the water-entry impact, which can lessen the impact and delay the time of peak value. In addition, the cavitation configuration has shrunk, especially in the water-air area. With the increase in water-entry velocity, the velocity damping becomes quicker. The acceleration is relatively higher in the beginning of water-entry. During the period of the model covered by supercavitation, the acceleration gradually declines and changes gently with the increase in water-entry depth. Key