Experimental study on propane jet fire hazards: Comparison of main geometrical features with empirical models

• Geometry of the horizontal LPG jet flame is studied.
• Palacios correlation is a good fit for all nozzle exit velocities.
• Santos and Costa (2005) and Sonju and Hustad (1985) is found to fit well for low exit velocities.
• Existence of buoyancy dominated regime in all the jet fire trials.
• Linear relationship for the lift-off length.

An experimental study of jet fires is performed to understand the flame geometry of jet fires. Horizontal jet fire experiments are performed by varying the mass flow rate of fuel through a 19 mm nozzle. The exit velocities varied from 25 to 210 m/s, flame lengths from 1 to 6 m and Froude Numbers from 2 × 103 to 2 × 105. The experimental measurement includes the flame detection using standard CCD camera to capture the details of flame morphology. The frames obtained from CCD camera are reconstructed using image visualization technique to obtain the flame morphology like flame length and lift-off length. The modeling includes comparison of experimentally determined jet flames with empirical correlations. The flame length is well validated with three empirical correlations. The lift-off length is found to be under-predicted by all the models. With extended analysis on image processing, it is observed that lift-off length is sensitive to the threshold intensity value chosen for image processing, whereas, flame length parameter is independent of the threshold intensity value. The deviation between experimental and predicted values is also attributed to soot formation which affects the lift-off lengths and the heat radiated by jet fires. The flame area obtained from image visualization methods are compared to flame area obtained from empirical models. The effect of air entrainment is also studied on flame geometry. It is observed that the horizontal extent of visible flame length is affected by the wind flowing in the downwind direction of jet fire. The vertical extent of the jet fires is found to reduce with wind flowing in the crosswind direction.