Experimental research on natural gas leakage underwater and burning flame on the water surface

Abstract

This paper presents an experimental investigation into the flow rate of natural gas released underwater from a pipe orifice and the associated combustion behavior on the water surface in an aerodynamic channel. A stainless-steel pipeline with a diameter of 25 mm was placed in a water tank of 1 m (height) ×0.5 m (width) ×0.5 m (length). Methane gas was released from a cylinder controlled by a flow meter and pressure gauge. Ten k-type thermocouples, fixed in two directions, were used to measure the temperature profile. The variation parameters of orifice diameter (1 mm, 3 mm, 5 mm), pressure range (0.02 to 0.55 MPa) and gas release depth (0.4 m, 0.6 m, and 0.8 m) were varied to study the flame geometry and temperature profile. A digital CCD camera and an infrared camera are employed to record the visible and temperature distribution, respectively. Results show that flame temperature decreases vertically; an initially high temperature region in the core flame quickly decreases in the plume region. Flame oscillation behavior is due to gas diffusion and flame turbulence. The stability of a burning flame is dependent on an increase in leakage pressure and large orifice diameter; shallow water depths provide greater flame stability. A new correlation is proposed to characterize the flame height to diameter ratio and the dimensionless heat release rate Q*.