Experimental study of the evaporation characteristics of unsymmetrical dimethylhydrazine in a sub-supercritical environment

In this study, the temperature–pressure separation technique was used to successfully obtain the process of the unsymmetrical dimethylhydrazine droplet diameter variation with time during evaporation in subcritical, supercritical, and far-supercritical environments at temperatures and pressures of 473–773 K and 1–9 MPa, respectively. The results show that unsymmetrical dimethylhydrazine droplet evaporation has two characteristic stages, transient heating and steady-state evaporation, under low-pressure and low-temperature environments; the steady-state evaporation stage influences droplet evaporation life more than the transient heating stage. Under high-pressure and high-temperature environments, droplet evaporation shows only a single feature of steady-state evaporation, and the droplet expansion process in the transient heating stage disappears. The normalized droplet lifetime decreased exponentially with temperature and decreased linearly and monotonically with pressure. The evaporation rate constant increases linearly and monotonically with temperature and exponentially with pressure.