Ethylene–air detonation in water spray

• DOI: 10.1007/s00193-016-0679-3
• Publication Date: 2016-07-21T04:32:46Z
• Authors: G. Jarsalé; F. Virot; A. Chinnayya
• Keywords: 02 engineering and technology; 0204 chemical engineering

Detonation experiments are conducted in a 52 $$\hbox {mm}$$ square channel with an ethylene–air gaseous mixture with dispersed liquid water droplets. The tests were conducted with a fuel–air equivalence ratio ranging from 0.9 to 1.1 at atmospheric pressure. An ultrasonic atomizer generates a polydisperse liquid water spray with droplet diameters of 8.5–12 $$\upmu \hbox {m}$$ , yielding an effective density of 100–120 $$\hbox {g}/\hbox {m}^{3}$$ . Pressure signals from seven transducers and cellular structure are recorded for each test. The detonation structure in the two-phase mixture exhibits a gaseous-like behaviour. The pressure profile in the expansion fan is not affected by the addition of water. A small detonation velocity deficit of up to 5 % was measured. However, the investigation highlights a dramatic increase in the cell size ( $$\lambda $$ ) associated with the increase in the liquid water mass fraction in the two-phase mixture. The detonation structure evolves from a multi-cell to a half-cell mode. The analysis of the decay of the post-shock pressure fluctuations reveals that the ratio of the hydrodynamic thickness over the cell size ( $$x_{{\mathrm {HT}}}/{\lambda }$$ ) remains quite constant, between 5 and 7. A slight decrease of this ratio is observed as the liquid water mass fraction is increased, or the ethylene–air mixture is made leaner.