In this paper, the atomization characteristics of an effervescent atomizer were investigated. The velocity, Sauter Mean Diameter (SMD) and atomization cone angle of the droplets were measured using the Phase Doppler Analyzer (PDA) to discuss the effect of different design parameters. The results showed that the atomization was unstable at a small Gas-Liquid Rate (GLR) while the atomization proved gradually by increasing the GLR. The optimal atomization region was at a GLR=0.1. In the atomization process, there existed a typical velocity distribution for the swirl atomizer. The design parameters of atomizer provided a great influence on the Sauter Mean Diameter (SMD) and atomization cone angle. The experiment results showed that some droplets had negative velocities.
In certain industries, such as the Chinese pharmaceutical pill preparation medicines, the occurrence of satellite droplets and the inconsistent diameters of the main droplets lead to wasted resources and affect the normal operation of the production system. So it is necessary to investigate the formation process of main droplets and the elimination method of satellite droplets in the jet process. In this paper, the effects of the liquid level height, dropper inner diameter, and glycerin mass fraction on the formation of the droplets are revealed, and the optimal frequency for eliminating satellite droplets is explored. The results show that the diameter of the main droplets increases as the liquid level height and the dropper inner diameter increase and decreases as the glycerin mass fraction increases. The fracture length has a growing trend as the liquid level, dropper inner diameter, and glycerin mass fraction increase. With the increase in the dropper inner diameter and glycerin mass fraction, the generation period increases. However, the increase in the liquid level height has an opposite influence on the other parameters. The optimal frequency for eliminating satellite droplets increases as the liquid level height and dropper inner diameter increase and decreases as the liquid becomes more viscous. However, the diameter and generation period of the main droplets decrease when a longitudinal disturbance is added to the jet system.
The combustion instability in a propulsion system is a ubiquitous problem. The radial baffles usually installed on the injector faceplate eliminate the combustion instability (acoustic pressure oscillation) in the propulsion system. In this article, the longitudinal baffles are installed on the inner surface of the combustor wall to control the combustion instabilities. The first-order and second-order tangential modes are induced in the experiments. The effects of the parameters of the baffle on the acoustic pressure oscillation in the cylindrical combustor are investigated. The effect of the combustor nozzle on the tangential modes has been systematically investigated. It is concluded that the eigen-frequency and amplitude of the first-order tangential mode decline with the increase in the longitudinal baffle number and height. For the second-order tangential mode, the eigen-frequency and amplitude monotonically increase until a maximum value (four baffles), subsequently decrease with the increase in the baffle number and height. The combustor without the nozzle obtains a lower frequency than that with the nozzle, especially for the low baffle height in the combustor.
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