Controlled and impulsive compression of an entrapped air bubble during impact

Utkarsh Jain, Devaraj van der Meer

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

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Abstract

Wave slamming onto a structure is often accompanied by the entrapment of an air pocket. A large scale impact typically has a rapidly evolving and disturbed liquid-gas interface, such that several bubbles are entrapped upon impact. While it is largely understood how the peak pressure is created by liquid coming into contact with the solid structure, it is more challenging to ascertain how an isolated air pocket is pressurised by an impulsive impact, and how the maximum impact pressure inside this bubble evolves. We study such a Bagnold-type impulsive compression of an air bubble by performing well-controlled experiments, where we use an inverted, hollow cone as an impactor. The cone is kept immersed throughout in a water bath, such that it encloses an air bubble of known and controlled volume. A high-sensitivity sensor measures pressures at the vertex of the cone. Using high-speed imaging we show how incoming liquid deforms the air bubble enclosed in such a geometry, and how an impact peak is registered inside the bubble, which can be traced back to the impact of a liquid jet onto the pressure sensor. We compare the measured pressures to a Bagnold model, and discuss the dominant resonances in the bubble. From visualisations of the deforming bubble, we also discuss the air-pocket’s deformations, resulting from the presence of surrounding rigid geometry (such as corrugations in an LNG containment membrane).

Original languageEnglish
Title of host publicationProceedings of the 32nd International Ocean and Polar Engineering Conference, ISOPE 2022
PublisherInternational Society of Offshore and Polar Engineers
Pages2270-2278
Number of pages9
ISBN (Print)9781880653814
Publication statusPublished - 2022
Event32nd International Ocean and Polar Engineering Conference, ISOPE 2022 - Shanghai, China
Duration: 5 Jun 202210 Jun 2022
Conference number: 32

Publication series

NameProceedings of the International Offshore and Polar Engineering Conference
ISSN (Print)1098-6189
ISSN (Electronic)1555-1792

Conference

Conference32nd International Ocean and Polar Engineering Conference, ISOPE 2022
Abbreviated titleISOPE 2022
Country/TerritoryChina
CityShanghai
Period5/06/2210/06/22

Keywords

  • adiabatic bubble compression
  • Bagnold impact
  • gas pocketed impact

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