Research On Supercavitation Flows Characteristics Of Complex Surface Shape And Successive Projectiles

With the developing and application of the supercavitation technology,high-speed underwater weapons such as the projectiles,the torpedoes and the vehicles et al,have been launched recently.That the density of water is 800 times that of air,leads the information transmission limited,target range and positioning accuracy low.Apart from high-speed photography to record and the sonar to detect,there is a lack of other means to detection.So the research of high-speed(above 100m/s)underwater vehicles by experimental methods is extremely difficult.The best method to research the high-speed supercavitation is numerical simulation.So far,the research on supercavitaion flow has made great progress,but there are many problems in application and mechanism of cavitation,which are not solved well.For example,how to reduce the drag of projectile furthest,the supercavitation of projectiles which are launched continuously and the supercavitaion of projectiles across medium or disturbance domains.Based on the above problems,the supercavitation flow is studied by the theoretical,numerical simulation and experimental comparison methods in this paper.The specific content of the article is as follows:(1)In order to study the maximum reduction drag mechanism of the supercavitation flow,the underwater projectiles with different grooves in the disc cavitators are chosen as the object of research.Based on the FLUENT commercial software and VOF(Volume of fraction)multiphase flows model.The three-dimensional supercavitation is simulated numerically.Besides,the three-dimensional characteristic of the supercavitating flows and the hydrodynamic are analyzed around underwater projectiles.The numerical simulation is effectively consistent with the theoretical analysis by comparing the numerical simulation result with the Principle of Independence of the Cavity Sections Expansion result.With the different grooves in the disc cavitators,the supercavitations are classical shape and the supercavitations with different cross section shape have the perfect self-repairing ability,which can be repaired to a smooth spheroid in a short time.(2)The mechanism of the interaction of a continuous projectiles supercavitation flow is studied numerically.Using the dynamic grid technology and UDF function,numerical calculation is carried out for supercavitation flow characteristics of two continuous and three continuous projectiles.Not only the interaction of continuous projectiles and the rule of supercavitation shape changed are summarized,but also the main factors of supercavitation flows of continuous projectiles,the drag coefficient curves of projectiles and the contour of velocity and the distribution of vortex et al.(3)In order to study the mechanism of multiphase medium interact with supercavitation,using the dynamic grid technique and Patch function to set flows field as the disturbance area,the supercavitation flows of projectiles across the disturbance area(multiphase medium)are simulated.It mainly includes two aspects: the single projectile across the disturbance areas with different widths and the continuous projectiles across the disturbance area.The projectile supercavitation flows acting on disturbance area and the interaction of supercavitation flows are studied.According to the results,the supercavitation in through the disturbance area will be completely suppressed with the increase of the width of the disturbance area,which is effectively consistent with the experimental results.It gives a comprehensive analysis about the high-speed vehicle supercavitation reduction drag,the interaction of continuous projectiles supercavitation flows and the supercavitation projectiles across disturbance area.The conclusion of this article can be referenced for the continuous projectile supercavitation and the projectiles across the disturbance area in experimental study and numerical simulation.