The Performance And Mechanism Of Bionic Structures On Submarine-launched Vehicle To Weaken Wave Impact And Enhance Desorption During Its Water-exit Process

Submarine-launched weapons have excellent maneuverability,concealment,and survivability,and are an important guarantee for national defense.Therefore,they have become important equipment for the development of major military powers.During the process of the submarine-launched vehicle(SLV)starting to contact the water-air interface at its head,crossing the water-air interface,and exiting the water,wave force impact and attached water loads(including tail plume)are two important factors that affect the stability of the SLV during its water-exit process.Strong coupling between the fluid and the wall can easily destabilize it,and even lead to its launch failure.Therefore,studying flow control techniques to reduce wave impact and reduce the attached water load(accelerating tail plume detachment)has important practical significance for improving the stability of the SLV.Inspired by the rapid and robust water-exit of humpback whales in wave conditions and the rapid and excellent desorption ability of kingfishers,experiments and numerical simulations were conducted to investigate the performance of the macro grooves at the head of the SLV in weakening wave impact,which simulates the groove of the belly of the humpback whale,and the ability to accelerate the desorption of surface adhesive water by constructing a surface patterned kingfisher feather microchannel structure,and reveal the relevant functional mechanisms.The main research contents are as follows:(1)Aiming at the problem that wave forces affect the stability of the SLV during its water-exit process,based on the morphological characteristics of macro grooves arranged orderly in the belly of humpback whales,regular macro grooves are constructed at the head of the SLV to reduce the impact of wave forces during its waterexit process.Using curved surface response design,taking the included angle of the groove edge line and the included angle of the adjacent groove centerline as factors,and using the aerodynamic force obtained from numerical simulation as an index,the influence of bionic groove parameters on the aerodynamic performance of the SLV is clarified,and it is determined that the bionic structure at a macro scale does not increase the aerodynamic resistance of the SLV.An orthogonal experimental design was used to develop a water-exit test scheme for the SLV in wave conditions,and a test platform for water-exit of the SLV in wave conditions was established.The effects of three factors of the groove structure at the head of the SLV(the inclination angle of the groove surface,the included angle of the groove edge line,and the included angle of the adjacent groove center line)on the wave force weakening performance were analyzed.The results show that the inclination angle of the groove surface has the greatest impact on the test index(maximum deflection angle),the included angle of the groove edge line takes the second place,and the included angle of the adjacent groove centerline has the smallest impact,moreover,the maximum deflection angle of the No.1 bionic SLV is 47.13% smaller than the prototype.Finally,in response to the phenomenon that the bionic structure of the head of the SLV in the experiment resulted in changes in the morphology of bubbles attached to its shoulder during its water-exit process(carried out from the launcher rather than formed by cavitation),a multi-angle water-exit test was conducted on the prototype and the No.1 bionic SLV in calm water.The results show that the morphological changes of the attached bubbles on the shoulder caused by the bionic structure of the SLV have little impact on the angular deflection during itswater-exit process.(2)A numerical simulation method based on VOF model and dynamic grid technology,combined with boundary wave generation method,was used to simulate the water-exit process of four types of the SLVs(prototype of SLV and three bionic SLVs in different states)in wave conditions.The results show that there is a small difference in the displacement of the centroid in the vertical and lateral directions between the prototype and the three bionic SLVs during their water-exit process,but the deflection angle of the three bionic SLVs after exiting the water is reduced by at least 58% compared to the prototype.During the water-exit process of the SLV,the pressure difference between the wave-exposed side and the protected side of the bionic SLV is smaller than that of the prototype.The grooves in the head of the bionic SLV weaken the impact of wave forces by reducing the "interference torque" of the SLV in the early stage of its water-exit process,and enhancing the "correction torque" of the bionic SLV in the later stage of its water-exit process.(3)Inspired by the ability of Kingfisher to quickly desorb the adhesive water on the body surface after predation and quickly complete a go-around,the hydrophobic surfaces with a micro groove mimicking kingfisher feathers were prepared.A test rig was built to test and analyze the desorption behavior of liquid droplets impacting the rapidly moving hydrophobic surface.The results show that the movement of the hydrophobic surface can reduce the contact time when the droplet impacts on the hydrophobic surface,and the contact time when the droplet impacts on the surface like kingfisher feather is 11.4%～37.7% less than that of the smooth surface at the same movement speed;when a droplet impacts on a hydrophobic surface at the same speed,its contact time slightly increases with the increase in the movement speed of the hydrophobic surface.The numerical simulation results based on the MPS method show that the micro grooves on the bionic hydrophobic surface can induce changes in the direction of particles inside the droplets,thereby promoting the redistribution of droplet mass,combined with the "ejection effect" caused by the liquid soaked in the micro grooves,the droplet detachment is accelerated.(4)SLV models with hydrophilic and hydrophobic surfaces were designed and manufactured,and a test rig was designed and built to test the water-exit process of the SLV under constant power traction.Water-exit tests were conducted on the SLVs with hydrophilic and hydrophobic surfaces under three constant power traction actions.The results show that adding a hydrophobic surface layer to the surface of the SLV can effectively reduce the detachment time of the adhesive water by 15.2% to 24% during the water-exit process.The numerical simulation results based on VOF model and dynamic grid technology show that when the SLV exits the water at a constant speed,the surface hydrophobic layer of the SLV reduces the desorption time of the adhesive water by 12.7% to 21%,and the hydrophobic layer causes the adhesive liquid film to break and fall off in advance,further reducing the negative pressure zone at the tail of the SLV,accelerating the wake separation.(5)Using the idea of combinatorial bionic design,a bionic hydrophobic SLV model with macro bionic grooves on its head and micro grooves on its main body surface that mimics kingfisher feathers was designed and fabricated,and its water-exit tests under constant power traction was conducted.The results show that compared with hydrophobic SLV,the breaking effect of the liquid film during the water-exit process of the bionic hydrophobic SLV is significantly improved,and the additional resistance caused by the adhesive liquid film is reduced.The wake separation time of the bionic superhydrophobic SLV is further reduced by 4.7%.