离心喷嘴脉冲工作动态特性实验研究

The specific impulse of the bipropellant thruster decreases significantly under short pulse conditions. In order to find out the reason from the perspective of propellant atomization，a cold flow test platform for pulsed working swirl injectors was set up，and a hydrodynamic mechanical pulsator was used to make the injector work in pulse mode. The dynamic pressure drop of the swirl injector and the oscillation of the Sauter mean diameter（SMD）over time were measured. Transient images of the spray field and the flow inside the injector were captured by a high-speed camera. The oscillation of the spray cone angle was measured by the method of extracting the image boundaries，and the time proportion distribution of different SMD values over a period was calculated. Transient images and SMD measurement results show that columnar jet or thick liquid ring formed by the Klystron effect will appear during pulse working conditions for the swirl injector，resulting in larger droplets in the spray field. The measurement results of spray cone angle show that the liquid sheet does not shrink directly with the drop of the pressure，but keeps a large angle for a certain time. The analysis of SMD shows that the smaller the pulse width is，the greater the proportions of unsteady spray time in a pulse，resulting in a worse atomization quality. According to the research results of this paper，in order to improve the atomization performance of the swirl injectors at narrow pulse width，it is necessary to eliminate the influence of columnar jet and the Klystron effect.