Leveraging CFD to Effectively Evaluate Sensitivity to Ignition Location When Designing for Explosion Loads

Vapor cloud explosions are among the most dangerous high consequence events that can occur at petrochemical facilities. As the size and complexity of facilities increase, designs must consider the potential adverse effects associated with vapor cloud explosions in large congested areas. When evaluating facility siting issues such as building locations or blast ratings, it is critical to understand the variables that may affect the results—otherwise there is a risk of producing suboptimal results that could impact the safety of those at the facility.

Among the factors that are generally not well studied during facility siting evaluations is the sensitivity of explosion pressures to ignition location. Depending on the size of cloud and particular arrangement of congestion, there can be significant differences in the pressure measured at nearby buildings when varying the ignition position by just a few meters or with changes in elevation. Typical CFD studies consider only a few ignition locations and may only minimally explore the effects of ignition elevation. Further, phenomenological models are not suitable for investigation of the sensitivity to ignition location.

This paper will explain via a series of case studies the importance of evaluating sensitivity to ignition location in more detail. The paper will also demonstrate a novel technique that can be used to visualize the sensitivity of specific targets to ignition location—thus making it easier to communicate results and identify areas of concern.