An Improved Emergency Blow Theoretical Model for Naval Submarine Blowing System and Experimental Verification

Abstract

An improved emergency blow model is proposed, which is based on the traditional emergency blow model and takes into account the influence of compressed air overflows from flood holes in the later stage of blowing. In order to verify the prediction accuracy of the improved emergency blow model for tank blowing, the full-scale model experiment of tank blowing was conducted to investigate the effects of air source volume, air source initial pressure, and flood holes diameters on blowing. The process of air release from bottle and main ballast tank drainage can be accurately simulated by the improved emergency blow model, and the prediction error of tank air peak pressure is shown to be <10%. Additionally, it is found that the air source volume has no effect on the tank’s air peak pressure or tank drainage rate. By analyzing the dynamic characteristics of tank air pressure, it is found that the dynamic change trend of air pressure differs between flood holes with small and large diameters. In the small diameter conditions, the air pressure reaches the maximum when the compressed air just enters the tank; however, under large diameter conditions, the peak pressure comes before the accumulated air pressure is released. The experiment and simulation demonstrate that increasing the area of the flood holes has a decreasing effect on the amount of air accumulated in the tank, and that the decreasing effect becomes more pronounced as the air source initial pressure increases. To carry out military operations, submarines are deployed both underwater and close to the open surface. About 170 submarines have sunk since they were originally created as a result of an accident, such as a fire, explosion, malfunction, grounding, or collision (Park & Kim 2017). Submarines run the risk of losing safety control in these critical situations. The best method of self-rescue is emergency floating to the surface to prevent bottoming or going deeper than allowed (Liu et al. 2009). A key factor in emergency rising to the water’s surface is the compressed air blowing mechanism. In such an operation, supplying air to the main ballast tank and blowing out ballast water should be used to achieve positive buoyancy or recover a positive pitching moment, which can be used to restore the safe depth of the submarine. Emergency blow is the term used to describe the process of directly supplying air to the main ballast tank without using a high-pressure valve column. The emergency blow is explored in this work because its influence is significantly greater than that of usual blowing, or traditional blowing.