Speaker
Description
Understanding the combustion processes under transcritical or supercritical conditions is vital for optimizing combustion systems and advancing our knowledge of fluid dynamics under extreme conditions. In this study, we have investigated the phase change characteristics of cyclopentane, a surrogate fuel, under varying conditions near the critical point, using a high-pressure spray chamber within the framework of the dtec.bw project MaST - Macro/Micro-simulation of Phase Separation Phenomena in the Transcritical Regime. The experiment involved three distinct scenarios, characterized by different pressure and temperature conditions. Focused shadowgraphy enabled detailed observation of droplet behavior. Our findings highlight varying phase change processes, depending on the experimental conditions. While in a typical evaporation process the droplet maintains a spherical shape and gradually diminishes, under supercritical conditions, the droplet exhibits significant distortion and eventually diffuses into the surroundings due to zero surface tension. Interestingly, in a high heat transfer environment, the droplet undergoes vibration and an explosive "supernova" like behavior, potentially due to internal nucleate boiling. These observations significantly contribute to the understanding of phase separation phenomena in the transcritical regime and provide useful data for future simulations and theoretical models. Further quantitative experiments and numerical simulations are recommended for a detailed exploration of these diverse phase change regimes.
References
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| Keywords | Phase change, Droplet, Near critical condition, Focused shadowgraphy |
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