Influence of Immersed Conductive Objects on Quasi-Steady Burning Behavior of Fuel Slick in Turbulent Waters

Abstract

ABSTRACT In situ burning (ISB) is an effective technique for burning oil spills that occur in oceans. The need for enhancing the burning characteristics and advancing the technique of burning fuels on the water sublayer has been identified. Following this, the study analyzes the steady burning behavior of a fuel layer floating on a turbulent water surface. The turbulent water surface is generated using an experimental platform comprising an axisymmetric upward-pointing submerged jet, an approach used in studies of free-surface turbulence. The turbulence is isotropic in the horizontal plane and bulk-flow free, with a turbulence intensity equal to 1.7 cm/s comparable to water turbulence in a calm ocean. The turbulent boundary condition causes an increase in heat extraction from the bottom of the fuel layer, thereby reducing the mass burning rate by 45% compared to a case with no turbulence. To improve the burning under turbulent water sublayer condition, a 10 mm conductive object is immersed at different depths in the fuel. The copper rod collects the flame’s heat and transmits it into the fuel layer via conduction, thereby increasing the burning rate by more than 1.4 times. A heat transfer model shows that the case with a small rod immersion depth (~10 mm) in a 40 mm fuel layer is best at improving burning because the heat losses from the object to the water sublayer are the lowest. The model also shows that the heat from the flame transmitted by the rod is primarily distributed in a region close to the surface of the fuel, where nucleate boiling is observed around the rod surface. As more of the rod is immersed in the fuel layer, the heat dissipation to the turbulent water increases nearly five times, thereby reducing the bubbling around the rod surface and the burning rate. The implications of burning fuel slicks for fast, slick cleanup during in-situ burning in turbulent water conditions are espoused.