(151a) Hydrogen Jet Vapor Cloud Explosion: New Tests, Blast and Fireball Models

Delayed ignition of a hydrogen jet release from vents and accidental releases can lead to a Jet Vapor Cloud Explosion (JVCE) with damaging blast loads and thermal hazards from the initial fireball and subsequent jet fire. Such hazards should be accounted for when developing vent stack design and separation distances and when performing an overall facility risk assessment. The authors, with others, have previously presented a model for predicting the JVCE blast overpressure for high-pressure choked hydrogen releases. Subsequent real-world incidents have shown the JVCE phenomenon occurring for lower pressure non-choked releases, with an initial fireball that may extend downwards below the release elevation.

To investigate non-choked JVCE and fireball phenomenon, Air Products and BakerRisk conducted more than 20 delayed ignition hydrogen jet release tests over a wide range of release velocities and temperatures. This paper presents the new test data, comparison with computational fluid dynamics (CFD) predictions, and new engineering models for blast load and fireball predictions. Comparison of the test jet fire results with a previously published Air Products model will be presented in a subsequent paper.