Study On The Underwater Ignition Process Of Solid Rocket Motor

Solid rocket motors have a simple structure,good maneuverability,and high reliability,making them one of the main power devices of modern high-speed weapons.The ignition process of solid rocket motors involves complex flow,heat transfer,chemical reactions.Underwater solid rocket motors operate in a liquid environment,resulting in significant differences in their operating characteristics compared to those in the atmosphere.Therefore,studying the underwater ignition process of solid rocket motors is of great significance for underwater launch,high-speed underwater vehicles,and so on.In order to study the underwater ignition process of solid rocket motors,this paper uses the commercial numerical simulation software FLUENT,uses the self compiled udf source term model to simulate the ignition process of solid rocket motors,uses the mixture model,the Realizable k-ε turbulence model,solves the high Reynolds number N-S equation,simulates the interaction between the gas jet and the water environment,and establishes the underwater ignition model of solid rocket motors,And compared with previous experimental studies,the accuracy of the model was verified.By calculating typical operating conditions,it was found that the engine experienced a pressure peak in the early ignition stage.After the plug was opened,the gas and water interacted violently,resulting in a typical phenomenon of bulging,radial contraction,and rebound.At the moment when the plug is opened,there is an additional thrust in the engine.Subsequently,due to the continuous expansion and contraction of the gas at the nozzle outlet,the engine thrust oscillates widely,resulting in thrust loss.Further research was conducted on the influencing factors of underwater ignition process,and it was found that the impact of different plug opening pressures on the engine is mainly reflected in the initial stage of gas jet,which has a significant impact on the internal flow field and gas jet evolution of the engine.The evolution process of the gas jet and the thrust characteristics of the engine are mainly influenced by the different depths of water and the different velocities of the projectile body.It was found that there are three different states of thrust characteristics during the underwater ignition process of the solid rocket.In the highly underexpanded state,the thrust is stable with almost no thrust loss.In the case of excessive height expansion,the thrust is relatively stable,but the loss of thrust is very serious.Between the two,there is a transition state.The combined action of water depth and missile body speed results in wide amplitude oscillation of engine thrust,and the thrust loss is between the first two.Propose the use of ventilated super-cavitation technology to improve engine thrust performance.The encapsulation of cavitation can reduce the impact of liquid on the nozzle.The ventilated cavitation adheres to the rear of the projectile to form a "protective layer" that isolates liquid and gas,keeping the nozzle thrust relatively stable and significantly increasing the average thrust.The thrust loss decreases significantly,reaching an acceptable value.A three-dimensional model was established to simulate the underwater ignition process of solid waste,and transient simulation was conducted.The three-dimensional calculation results were obtained to verify the feasibility of conducting water tunnel experiments,laying the foundation for further experimental research.