Abstract
This paper describes an experimental and a numerical study of a recently developed high-efficiency, low-resistance launching method for an underwater launcher. The so-called gas-curtain launch method overcomes the problems of poor safety and low muzzle velocity in traditional fully submerged launchers. By introducing part of the gas inside the chamber to the front of the projectile, the water inside the barrel will be driven out. A low-resistance gas passage is then provided for projectile motion in the bore, thus delivering better interior ballistics performance than that in fully submerged launchers. Experiments are carried out using a 12.7-mm underwater launcher. A pressure sensor is used to record the chamber pressure, and high-speed video recordings allow the projectile motion around the muzzle to be determined. The experimental results show that the muzzle velocity is 172.8 m/s and the maximum chamber pressure reaches 116.0 MPa in a fully submerged launch, compared with a maximum chamber pressure of only 41.8 MPa and a muzzle velocity of 177.5 m/s when the gas-curtain launch method is adopted. The significant drag reduction effect of the gas-curtain launch greatly improves the interior ballistics performance, reducing the maximum chamber pressure by about 64.1% while retaining a similar muzzle velocity. Following the experiments, a numerical model is established and simulations are performed under various ventilation mass rates. The results clarify the drag reduction mechanism and the partial characteristics of the flow field in the gas-curtain launch.
Highlights
It is difficult for underwater vehicles such as torpedoes and submarines to attain high speeds due to the huge level of water resistance
This paper has described an experimental and a numerical study of a drag-reduction method for an underwater launcher
The maximum chamber pressure can, be reduced by about 64.1% while retaining a similar muzzle velocity when compared with the fully submerged launch
Summary
It is difficult for underwater vehicles such as torpedoes and submarines to attain high speeds due to the huge level of water resistance. drag reduction has become a key technology for underwater vehicles. The ideal drag reduction effect for underwater submerged launchers would involve the barrel being filled with gas during the shooting process. This can be achieved in two ways. Stace proposed sealing the launcher muzzle with a complicated device to prevent water from entering the barrel. This involves the use of a sealing baffle and a member that is fixed to the muzzle. There have been few reports on the interior ballistics characteristics of underwater launchers On this basis, an experimental launch system based on a 12.7-mm machine launcher is designed to carry out experimental research on the proposed drag reduction method for underwater submerged launchers. The advantages of the gas-curtain launch compared with the traditional fully submerged launch are verified
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