Numerical Study Of Spray Cooling With Suddenness Blast-off Of The Rocket Motor In A Magazine

There are lots of different ammunition in the magazine of the warship. The safety ofmagazine is a very important factor of the warship. If the accidental ignition occurs, the hightemperature exhausted gas from the rocket motor will heat the other ammunition, whichpossesses the energetic materials, such as solid propellant and liquid propellant, which is verysensitive to fire and may explode. It is very dangerous to the warship. Therefore, it is essentialto make the magazine cooling rapidly. The exhausted gas flow fields are simulated with theFluent Software in the case of accidental ignition of the rocket motor in the magazine ofwarship. The component transport and the DPM are used to simulate the spray coolingprocess and the exhausted gas physical fields in the magazine. The main contents of thisdissertation are as followed.Firstly, The atomization mechanism of swirl pressure nozzle is analyzed in details. Thechange of the velocity and pressure distribution in the swirl pressure nozzle are calculated bythe numerical methods. And the results show that the pressure of atomization, nozzle diameterand cone angle are the main factors to the droplet size distribution.Secondly, The force and motion, broken of the droplet, as well as the performance of theheat and mass transfer are introduced in the paper. Evaporation of single droplet isinvestigated with different velocities and diameters in different temperature conditions. Andthe results show that the vaporization time of the droplet is controlled by the parameters ofdroplet, such as temperature, diameter and velocity.Finally, numerical simulation, covering the aspects of such characteristics as thepositions of the spray nozzles and their number, the starting spray, intensity, the cone angle ofthe spray and the water temperature, are carried out to study their effect on the spray coolingin the magazine. The results of simulation show that the temperature in the magazine dropssignificantly after the spray cooling and the temperature in the most area of the magazinedeclines below400K within3seconds, after which the temperature reduces slowly. Incontrast, the cooling effect in the zone of impinging jets is not ideal, thus the magazinebackplane requires special thermal insulation. Considering the randomness of the fire source,it is beneficial for the liquid distribution in the magazine so that the cooling efficiency will beimproved correspondingly after such application as the nozzles arranges as evenly as possible, a suitable number of nozzles, and a larger cone angle of the spray. Besides, when the sprayintensity increases to a certain extent, the cooling efficiency in the magazine will slowlyapproach a constant if the spray intensity continues to enhance.