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Buoyancy effects on combustion products from high-pressure hydrogen jet flames

Wijesekere, Thushadh LU orcid ; Runefors, Marcus LU orcid and Wilkens Flecknoe-Brown, Konrad LU orcid (2026) In Fire Safety Journal 159.
Abstract
Due to the lower radiative fraction and typically higher storage pressures, gas temperatures can often result in longer safety distances compared to radiative heat transfer for hydrogen jet flames. The high temperatures, however, also lead to a low density causing the flow to rise at a certain distance from the release. Unfortunately, a model to determine this distance, similar to what is available for unignited releases, is currently not available which this paper aim to provide. An experimental study was conducted investigating the buoyancy effect on ignited horizontal hydrogen jet releases with different release diameters. The invisible hydrogen plume was visualized using a Background Oriented Schlieren technique (BOS). The transition... (More)
Due to the lower radiative fraction and typically higher storage pressures, gas temperatures can often result in longer safety distances compared to radiative heat transfer for hydrogen jet flames. The high temperatures, however, also lead to a low density causing the flow to rise at a certain distance from the release. Unfortunately, a model to determine this distance, similar to what is available for unignited releases, is currently not available which this paper aim to provide. An experimental study was conducted investigating the buoyancy effect on ignited horizontal hydrogen jet releases with different release diameters. The invisible hydrogen plume was visualized using a Background Oriented Schlieren technique (BOS). The transition of the initial momentum-driven jet into a fully buoyancy-driven jet was estimated by following the gradient of the centerline of the plume. A model based on the Froude number of the release similar to the model for unignited releases was developed and the distance showed a very similar dependence on the Froude number, but giving consistently approximately 39% shorter distances. (Less)
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Background oriented Schlieren (BOS), Jet fires, Plumes, Safety distances
in
Fire Safety Journal
volume
159
publisher
Elsevier
external identifiers
  • scopus:105022612378
ISSN
0379-7112
DOI
10.1016/j.firesaf.2025.104587
language
English
LU publication?
yes
id
2369dd25-2b3f-49fc-94bd-fd47e91a3413
date added to LUP
2025-12-10 16:02:43
date last changed
2025-12-15 10:45:17
@article{2369dd25-2b3f-49fc-94bd-fd47e91a3413,
  abstract     = {{Due to the lower radiative fraction and typically higher storage pressures, gas temperatures can often result in longer safety distances compared to radiative heat transfer for hydrogen jet flames. The high temperatures, however, also lead to a low density causing the flow to rise at a certain distance from the release. Unfortunately, a model to determine this distance, similar to what is available for unignited releases, is currently not available which this paper aim to provide. An experimental study was conducted investigating the buoyancy effect on ignited horizontal hydrogen jet releases with different release diameters. The invisible hydrogen plume was visualized using a Background Oriented Schlieren technique (BOS). The transition of the initial momentum-driven jet into a fully buoyancy-driven jet was estimated by following the gradient of the centerline of the plume. A model based on the Froude number of the release similar to the model for unignited releases was developed and the distance showed a very similar dependence on the Froude number, but giving consistently approximately 39% shorter distances.}},
  author       = {{Wijesekere, Thushadh and Runefors, Marcus and Wilkens Flecknoe-Brown, Konrad}},
  issn         = {{0379-7112}},
  keywords     = {{Background oriented Schlieren (BOS); Jet fires; Plumes; Safety distances}},
  language     = {{eng}},
  month        = {{01}},
  publisher    = {{Elsevier}},
  series       = {{Fire Safety Journal}},
  title        = {{Buoyancy effects on combustion products from high-pressure hydrogen jet flames}},
  url          = {{http://dx.doi.org/10.1016/j.firesaf.2025.104587}},
  doi          = {{10.1016/j.firesaf.2025.104587}},
  volume       = {{159}},
  year         = {{2026}},
}