In order to better and faster calculate nozzle performance, a program for calculating the chemical dynamic flow field of two dimensional nozzles is developed by using the method of characteristic and boundary layer correction. The nozzle field corresponding to different for a liquid oxymethane engine, and the influence of different design parameters on nozzle efficiency are studied, the design parameters include thrust, chamber pressure, nozzle area ratio and nozzle outlet angle, etc. Geometric loss, boundary layer loss and chemical dynamic loss are considered in the calculation of nozzle efficiency. The results show that the program can obtain the number important for engineer quickly and accurately, improve the simulation efficiency greatly, and can be used to optimize the nozzle contour.

Aiming to study the wave effects on the water-exit process of aquatic-aerial vehicles, a hemispherical-head axisymmetric vehicle are simulated to exit through different irregular waves based on the P-M spectrum. Both kinetic and dynamic profiles of the vehicle are extracted. The results demonstrate that the normal force mainly originates from the asymmetric pressure distribution on the cylinder part of the vehicle, and the pitching moment from the asymmetry on the head and the tail. Concerning the horizontal displacement of the gravity center and the pitching angle, the magnitudes are entwined with the height difference between the crest and trough that the vehicle encounters, while the directions with the stage of the crest/trough transition.

The tilting of the rotor of constant speed hydraulic motor driven by high pressure kerosene (hydraulic motor for short) is introduced, and the tilting mechanisms are analyzed. According to the causes, the tilting phenomenon is grouped into initiative tilting and passive tilting. The research on initiative capsizing is carried out emphatically, the mathematical expression is derived based on the mechanics analyzing of the rotor and pistons, and the dimensionless tilting safety factor is introduced to quantify the tilting risk. The causes of passive capsizing are analyzed, and the corresponding solutions are proposed. The initiative tilting and passive tilting should be avoided during the product designing process.

In order to investigate the evolution of vertical water-entry cavity of a sphere, a numerical simulation for modeling the vertical water-entry of a sphere was performed, which is based on Navier-Stokes equations, volume of fluid model and dynamic mesh. It showed that numerical results compared favorably with the experimental results, which verified the accuracy of the simulation method. In addition, during the early period of the water entry, there was a high impact load on the sphere and a splash rose from the surface, and then a water-entry cavity which was open to the atmosphere formed. The cavity experienced development, closure and collapse periods after its formation. Pressure acting on the cavity was the main cause of the deep closure, and high speed up-jet and down-jet appeared after the closure.