Under-expanded supersonic CO ₂ freezing jets during champagne cork popping

Abstract

During champagne cork popping, the CO2/H2O gas mixture initially under pressure in the bottleneck freely expands into ambient air and experiences adiabatic cooling. A comparison between the condensation phenomena accompanying cork popping from bottles stored at 20° and 30°C was made. The initial headspace-to-ambient-pressure ratio much exceeded the critical ratio needed for the gas mixture to reach Mach 1, thus forming under-expanded supersonic CO2 freezing jets expelled from the throat of the bottlenecks. It was emphasized that, after adiabatic cooling and with a saturation ratio for gas-phase CO2 about twice higher for the bottles stored at 30°C, dry ice CO2 clusters grow bigger and reach the critical size needed to achieve the Mie scattering of light. Moreover, during the very first millisecond following cork popping, evanescent normal shock waves (or Mach disks) were unveiled in the jets, until the reservoir-to-ambient-pressure ratio goes below a critical ratio.

Computational fluid dynamic simulation of the supersonic CO2 flow during champagne cork popping

“…5 Even more recently, a ACCEPTED MANUSCRIPT/ CLEAN COPY 3 comparison between the condensation phenomena accompanying cork popping from bottles stored at 20 and 30 °C was made. 6 The initial bottleneck-to-ambient-pressure ratio (7.5 for the bottles stored at 20 °C, compared to about 10 for those stored at 30 °C) much exceeded the critical ratio needed for the CO2/H2O gas mixture to reach Mach 1. In these cases, under-expanded supersonic jets got expelled from the throat of the bottlenecks.…”

“…Moreover, during the very first millisecond following the cork popping process, evanescent normal shock waves were identified in the plumes, until the reservoir-to-ambient-pressure ratio went below a critical value needed for their formation, which were de facto seen vanishing. 6 In fact, the expansion of a high-pressure gas due to sudden exposure to a lowpressure environment gives rise to a so-called free jet, as opposed to a jet confined by the walls of a duct. The free jet acquires supersonic speed when the sonic state gets reached at the outlet that separates the high-and low-pressure areas.…”

Standing shock prevents propagation of sparks in supersonic explosive flows

“…Upstream of the Mach disk the gas expands supersonically, dropping in pressure by 2 orders of magnitude and temperature to below 50 K. While the simulation does not account for phase changes such as heating due to condensation, this cooling is large enough for the argon to reach temperatures and pressures corresponding to the liquid-vapor phase interface 24 . In this case the presence of particles should enhance inhomogeneous nucleation, making it reasonable to assume that the condensation visible in the images is due to argon condensing 25 . The Mach disk is surrounded by supersonic flows bounded by the shear layer between the expanding gas and the background atmosphere.…”

Culinary fluid mechanics and other currents in food science

“…This uncorking process is also accompanied by the formation of a small fog cloud just above the bottle opening. It has been shown recently that uncorking champagne creates supersonic CO 2 freezing jets [272]. What is the underlying physical principle behind these interesting phenomena?…”