Multiphase marine ramjet using liquefied gas as a source of bubbles

Herman D. Haustein, Alon Gany*, Ezra Elias

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


An innovative variant of a multiphase marine ramjet is investigated analytically and experimentally. Pressure liquefied gas (LG) is injected, boiling under superheat conditions in the water stream within the propulsion unit, and serving as an on-board bubble source necessary for the ramjet operation. Experiments were conducted in a 10 m diameter tow pool at a speed range of 7-18 m/s (approximately 14-35 knots). For the laboratory concept demonstration and process characterization, two liquefied gases, butane and R134a (synthetic refrigerant gas), were employed. In practical applications, non-polluting LGs such as liquid air may be used. The results reveal the overall performance comparable to the operation with pressurized air, with some thrust advantage of the LG at high-speed tests, attributed to the volume increase of gas during phase change, in accordance with the thermodynamic power cycle analysis.

Original languageEnglish
Article number710
JournalJournal of Marine Science and Engineering
Issue number9
StatePublished - Sep 2020


  • Boiling expansion work
  • Bubbly jet
  • Liquefied gas
  • Marine ramjet
  • Phase transfer propulsion
  • Two phase jet propulsion
  • Underwater propulsion


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