EXPERIMENTAL STUDY ON EVAPORATION AND MICRO-EXPLOSION CHARACTERISTICS OF OXYGEN-CONTAINING DROPLETS ON HIGH-TEMPERATURE WALL

Oxygen-containing fuel droplet is taken as the research object in this article, a high-temperature wall droplet evaporation test platform is built, and the consistency of the test system is verified. On this basis, the evaporation and micro-explosion characteristics of three oxygen-containing fuels, namely ethanol-biodiesel, polymethoxy dimethyl ether diesel (PODE-diesel), and ammonium dinitramide (ADN) solution, were studied at boiling point temperature and Leidenfrost temperature. The results show that the evaporation and micro-explosion characteristics of the three fuels exhibit different phenomena at two specific temperatures: unlike at boiling point temperature, ethanol-biodiesel droplets bounce or move mostly on high-temperature wall at Leidenfrost temperature, resulting in significantly longer delay and duration of droplet micro explosion, and relatively higher droplet micro-explosion intensity; At the Leidenfrost temperature, PODE-diesel droplets do not spread out significantly during the final evaporation process, and they basically disappear during wall bouncing or movement. The delay time and duration of droplet micro-explosion are relatively shorter, but the droplet micro-explosion intensity changes less; At the Leidenfrost temperature, ADN droplets will continuously bounce or move until the droplets completely disappear. The droplet micro-explosion has a small impact on the droplet volume (equivalent evaporation rate is 0), the delay time of droplet micro explosion becomes shorter, and the droplet micro-explosion intensity decreases to a certain extent. In addition, by comparing the micro-explosion characteristics of three types of fuels, it was found that at the boiling point temperature, ADN droplets not only produce bubbles during evaporation, but also undergo intense pyrolysis reactions between internal components, leading to ignition until the droplets disappear. The delay time of micro-explosion is relatively short, and the percentage of micro-explosion duration to droplet survival time is also the smallest, but the micro-explosion intensity of droplets is relatively large; The delay time of micro-explosion of PODE diesel droplets at boiling point temperature is relatively long, and the percentage of micro-explosion duration to droplet survival time is also large.