Scheme: Newton Advanced Fellowship
Organisation: Ulster University
Dates: Mar 2015-Feb 2018
Summary: Reserach area: combustion physics and flame dynamics in ambient air flows having applications for fire
The blow-out limits of nonpremixed turbulent jet flames in cross flows were studied, especially concerning the effect of ambient pressure, by conducting experiments at atmospheric and sub-atmospheric pressures. The combined effects of air flow and pressure were investigated by a series of experiments conducted in a specially built wind tunnel in Lhasa, a city on the Tibetan plateau where the altitude is 3650 m and the atmospheric pressure condition is naturally low (64 kPa). This is the first work reveals that the flame is harder to be stabilized or easier to be blown-out in a sub-atmospheric pressure than that in normal pressure. It was found that the blow-out limit of the air speed of the cross flow first increased (“cross flow dominant” regime) and then decreased (“fuel jet dominant” regime) as the fuel jet velocity increased in both pressures; however, the blow-out limit of the air speed of the cross flow was much lower at sub-atmospheric pressure than that at standard atmospheric pressure whereas the domain of the blow-out limit curve (in a plot of the air speed of the cross flow versus the fuel jet velocity) shrank as the pressure decreased. A new physical model based on Damköhler number for blow-out behavior with combined effects due to cross flow and sub-atmospheric pressure was brought forward. All these pioneer unique efforts contribute a big forward step to advance the understanding of our community on the stabilization of nonpremixed turbulent jet flames, from commonly in quiescent air and normal pressure condition in the past to a new field in cross flow and sub-atmospheric pressure conditions.