Experimental investigation of isolated acetone droplets at ambient and near-critical conditions, injected in a nitrogen atmosphere

¹ Institut für Thermodynamik der Luft- und Raumfahrt Universität Stuttgart Pfaffenwaldring 31, 70569 Stuttgart, Germany
² FG Reaktive Strömungen und Messtechnik, Maschinenbau Center of Smart Interfaces, TU Darmstadt Petersenstraße 32, Darmstadt 64287, Germany

Abstract

A new experimental setup is presented to investigate free falling acetone droplets at ambient to near-critical temperatures, injected in a heated and pressurized nitrogen atmosphere. Important considerations for the design are: a high reproducibility of the experiments, control of the temperature of the generated droplet independent from that of the chamber, and the homogeneity of the surroundings. In the reported experiments, chamber temperatures range from 293 to 523 K, chamber pressures from 1 to 60 bar and acetone injection temperatures from 293 to 466 K. The reproducibility of all experiments is found to be excellent when the chamber temperature is low (318 K or less). The droplet diameters under these circumstances are reproducible within 1%, even at the highest pressure of 60 bar. The droplet detachment time relatively to the external trigger is also very reproducible, within 0.5 ms. At higher chamber temperatures, the droplets are more sensitive to disturbances, but can still be created “on-demand.” The novel experimental setup is thus capable of generating reliable and comparable experiments at high pressures and temperatures up to supercritical chamber conditions.