Effects of ambient pressure on the instability of a liquid boiling explosively at the superheat limit

The effect of ambient pressure on the intrinsic instability of rapid vaporization in single droplets boiling explosively at the limit of superheat has been studied experimentally and theoretically. In a series of experiments with pentane, isopentane and ethyl ether in a bubble-column apparatus it has been shown that the baroclinic interfacial instability may be suppressed by increasing the ambient pressure. High-speed microphotography shows that, while at atmospheric pressure bubble boundaries are rough and opaque, at elevated pressure the liquid-vapor interface is smooth and transparent. Pressure measurements show that the radiated pressure field is two orders of magnitude smaller from stabilized bubbles than from unstable. At intermediate pressures bubble growth occurs in two stages, first stable then unstable. The transitional regime between unstable and stable vaporization provides convenient conditions or exhibiting many features of unstable vaporization.