a discussion of scaling the blue whirl

The blue whirl (BW) is a small, completely blue, soot-free flame that was originally seen as it evolved from small laboratory-scale fire whirl (FW) measurements of FWs burning liquid hydrocarbons on water. The BWs seen were about 2–2.5 cm in diameter and 6–8 cm in height and sat above the water. They were subsequently shown to be cleaner and safer than FWs. The suggestion, then, was that the soot-free nature of a BW would make it a perfect candidate for a clean energy source, and its burning efficiency could lead to better burners. The next questions, then, involve stability and scaling. Here we consider whether if and how the size of the BW might be changed to increase the rate of fuel consumption. A previous scaling analysis (Hariharan et al., Physical Review Fluids, 2020) based on the small BW data showed that a broad range of parameters could influence its formation and size. These include but are not limited to inflow velocity, type of inflow, fuel injection rate, and inlet area. We now show the implications of this scaling law and particular of the relation between vorticity and buoyancy in changing the size of the BW.