Abstract
To decrease the launching resistance of underwater guns, a new gas-curtain formation method is proposed based on the gas-curtain launching principle, which is setting up several rectangular grooves on the internal wall of the barrel to guide the gas flow to the front of the projectile and form a gas curtain. A three-dimensional unsteady two-phase flow model of the drainage is established. The formation and drainage characteristics of the gas curtain are studied under the different number of grooves with a constant injection area and 10 MPa injection pressure. The results indicate that the circumferential and radial converging effects of multi-gas jets are enhanced, but the axial expansion is enhanced first and then weakened when the number of grooves increases from 4 to 12. The vortex scale in the Taylor cavity increases with the increase in the number of grooves, but the distance moving downstream is shortened. The gas volume fraction in the tube increases with the increase in the number of grooves. However, the drainage efficiency of the gas curtain on the warhead increases first and then decreases with the increase in the number of grooves, while the change of the gas efficiency–cost ratio is just the opposite.
Highlights
Missiles and guns are important components of naval combat equipment
A three-dimensional unsteady two-phase flow model is established, and the drainage process of multi-wall gas jets in a 30 mm liquid-filled tube is simulated in this work
The formation and drainage characteristics of the gas curtain under different numbers of grooves are studied with the constant injection and 10 MPa injection pressure
Summary
May cause extremely high-motion resistance and chamber pressure because of the water column in the barrel. Its principles are guiding part of the gunpowder gas behind the projectile flow to the front before the projectile moves, forming a gas curtain for drainage, changing the medium in the barrel from water to gas, and launching the projectile in the gas channel. The empirical relationship between the axial expansion displacement of the gas curtain and the time is obtained within the range of injection pressure (12–18 MPa) through the experiments On this basis, Zhou and Yu15,16 designed a new porous structure, which changed the nozzle from the planar distribution on the projectile into conical distribution, and found that decreasing the lateral jet could reduce the average pressure on the radial direction section but will prolong the drainage time. The new method guides the gas flow from the back of the projectile to the front by several rectangular grooves designed on the inner wall of the barrel. It is expected to promote the engineering application of gas-curtain launching of underwater guns
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