Hydrodynamic Analysis Of Submerged Body During Emergency Surfacing

Submerged body contains submarine, diving vehicle, and other underwater vehicles. The submarine is a naval important deterrent, whose most important performance indexes is the mobility, stealth and emergency safety performance. With the increasing speed of submarine and diving depth growing, the submarine's movement under the water has been the space of 6 Degrees Of Freedom (6-DOF) movement. Submarine underwater will not be able to keep sailing in constant depth and may be in danger if encounters unexpected events, such as the longitudinal trim caused by equipment breakdown and the submarine's off the cliff resulted from the sudden change of sea water. In order to prevent the submarine, which is at risk,exceeding the extreme diving depth or being run down the bottom of the sea, the most effective means is blowing out water of the ballast tank quickly, even abandon the ballast,implement emergency ascent. This dissertation looks into the numerical calculation method of submerged body emergency ascent, the computational fluid dynamics (CFD) simulation of submerged body emergency ascent, and the emergency ascent experiments of submerged body model. The content as follows:Firstly, establishing the submerged body of emergency ascent mathematical model of the 6-DOF, and putting forward a feasible numerical calculation method according to the characteristics of the submerged body's floating movement, including RANSE control equations and Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm,, the Volume Of Fluid (VOF) and overset mesh technique, selects turbulence model, the grid division of compute domain, boundary conditions and so on.Secondly, With computational fluid dynamics (CFD) method, numerical simulation of the emergency floating process of opened hole water submerged body in 9 meters depth,which has better predicts the opened hole water submerged body do forward motion, the backward movement and close to the vertical movement of the hydrodynamic performance in the process of emergency ascent in 9 meters depth,and analyzes the effect of the different buoyancy center position on the submerged body emergency ascent.Thirdly, based on previous theoretical research results, completing the submerged body underwater tilt test, pitch and roll test, and underwater emergency ascent experiment of the submerged body in different conditions. The comparative analysis of Experiment data and CFD simulation validates the accuracy of numerical calculation theory,and summarizes a set of effective emergency floating scheme of the submerged body.Finally,using the verified feasible numerical calculation method,numerical predicts the movement rule of submerged body emergency ascent when drain holes is closed. And it analyzes the factors to hydrodynamic performance of submerged body emergency ascent,such as whether submerged body has drain holes or not,the different diving depth,the different buoyancy center position and so on.