Huang Chenguang

A Scaled Underwater Launch System Accomplished by Stress Wave Propagation Technique

A scaled underwater launch system based on the stress wave theory and the slip Hopkinson pressure bar (SHPB) technique is developed to study the phenomenon of cavitations and other hydrodynamic features of high-speed submerged bodies. The present system can achieve a transient acceleration in the water instead of long-time acceleration outside the water. The projectile can obtain a maximum speed of 30 m/s in about 200 mu s by the SHPB launcher. The cavitation characteristics in the stage of acceleration and deceleration are captured by the high-speed camera. The processes of cavitation inception, development and collapse are also simulated with the business software FLUENT, and the results are in good agreement with experiment. There is about 20-30% energy loss during the launching processes, the mechanism of energy loss is also preliminary investigated by measuring the energy of the incident bar and the projectile.

Shedding phenomenon of ventilated partial cavitation around an underwater projectile

A new shedding phenomenon of ventilated partial cavitations is observed around an axisymmetric projectile in a horizontal launching experiment. The experiment system is established based on SHPB launching and high speed photography. A numerical simulation is carried out based on the homogeneous mixture approach, and its predicted evolutions of cavities are compared with the experimental results. The cavity breaks off by the interaction between the gas injection and the re-entry jet at the middle location of the projectile, which is obviously different from natural cavitation. The mechanism of cavity breaking and shedding is investigated, and the influences of important factors are also discussed.

A Novel Micro-Scale Plastic Deformation Feature on a Bulk Metallic Glass Surface under Laser Shock Peening

Laser shocking peening is a widely applied surface treatment technique that can effectively improve the fatigue properties of metal parts. We observe many micro-scale arc plastic steps on the surface of Zr47.9Ti0.3Ni3.1Cu39.3Al9.4 metallic glass subjected to the ultra-high pressure and strain rate induced by laser shock peening. The scanning electronic microscopy and atomic force microscopy show that the arc plastic step (APS) has an arc boundary, 50-300 nm step height, 5-50 mu m radius and no preferable direction. These APSs have the ability to accommodate plastic deformation in the same way as shear band. This may indicate a new mechanism to accommodate the plastic deformation in amorphous metallic glass under high pressure, ultra-high strain rates, and short duration.

Studies on the Dynamic Buckling of Circular Plate Irradiated by Laser Beam

The dynamic buckling of thin copper plate induced by laser beam, was analyzed with the numerical integration and disturbance methods of controlling equation. The buckling and post-buckling of thin plate were shown, with the consideration of the temperature distribution, inertia effect and initial deflection. At last, the buckling criterion about the circular plate was obtained and used to investigate the relation between the critical laser intensity and the ratio of thickness and diameter of the plate. The results fit the experimental observation and the FEM simulation very well, and benefit to the understanding of failure phenomenon of structures irradiated by laser beam.

Study on maneuvering characteristics of blended wing body vehicle

Blended wing body vehicle with its unique shape and mobility has become an important direction of future development of the ocean, but people do not know much about sailing characteristics of it. In this paper, semi-relative method is adopted to calculate the maneuvering characteristics of blended wing body vehicle, the main influence parameters are got based on dimensional analysis. The tail vortex will change with the rotation radius at in a horizontal turning at given speed. The asymmetric of vortex is greater when the rotating radius is small. The vortex separation position is same with the constant rotating radius. The maneuvering characteristics in vertical turning is better than in horizontal turing, which means than the blended wing body vehicle has more advantages in changing depth maneuver operation.