Main geometrical features of horizontal buoyant jet fire and associated radiative fraction

Abstract

High momentum release of jet fire can be very intense, and the released heat can be very high, depending on the source capacity. One of the key parameters in characterizing the jet fire is the radiative fraction. The previous study has correlated the radiative fraction to the source using a Froude number basis. Nevertheless, the flame mechanism and associated geometrical features gave significant effects on the global radiative heat flux to some extent. Therefore, the characterization of the main geometrical features, particularly on jet flame structures at higher momentum release conditions and its correlation with the radiative fraction, are valuable to be investigated. In this work, propane was used as fuel and released through a 9.8 mm circular nozzle with the exit velocities were set ranging between 27 and 65 m/s. It was found that the liftoff length estimation from this work is in a good agreement with the jet fire release under sub-atmospheric pressure in a vertical orientation. Furthermore, the flame projected length and height were characterized by momentum-driven length (Lm) and buoyancy-driven height (Lb) by the dimensionless characteristics length (Ʌ). The experimental observations indicate that as the Ʌ ≥ 0.0001, the radiative fraction shows a decreasing trend.