CFD Analysis of Jet Fire
CFD can be used to evaluate the benefit of installing thermal hazard mitigation measures such as the use of thermal radiation barriers to protect against flame impingement.
An example is given below for a 2-inch methane jet flame test conducted by BakerRisk. The fuel was released into an area with a matrix of pipes designed to form a congestion zone. The wind speed at the time of the experiment was estimated to be 5 m/s with cross wind at an angle close to 45° relative to the fuel release direction. The source pressure was 250 psig and its temperature was ambient.
The figure below shows images of the flame taken from different angles during the test. The height of the congestion structure surrounding the flame is 6 ft, which indicates that the combined visual dimension of the flame (horizontal length and vertical height) is around 45 ft from the point of release (which is 10 ft upstream of congestion structure).
The Figure to follow shows the CFD results in the form of a 3D envelope of fuel concentration >0.1% mass fraction that defines the flame boundary. A comparison between the Figures 5 & 6 clearly shows that the predicted flame shape, height and length agree reasonably well with the test results. The test was performed in an open atmosphere and wind conditions were not controlled during the test period.
The testing efforts at BakerRisk in Jet Fire Research have led to significantly improved thermal radiation contour assessment methods.