NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Piloted Ignition of a Slick of Oil on a Water Sublayer: The Effect of Weathering.


pdf icon Piloted Ignition of a Slick of Oil on a Water Sublayer: The Effect of Weathering. (758 K)
Wu, N.; Kolb, G.; Torero, J. L.

Combustion Institute, Symposium (International) on Combustion, 27th. Proceedings. Volume 2. August 2-7, 1998, Boulder, CO, Combustion Institute, Pittsburgh, PA, 2783-2790 pp, 1998.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

combustion; oil spills; pilot ignition; water; temperature measurements; flow visualization; ignition delay; crude oil; weather effects

Abstract:

Piloted ignition of a slick of oil on a water sublayer has been experimentally studied. The objective of this work is to provide a tool that will serve to assess a fuel's ease to ignite under conditions that are representative of oil spills. The fuel is exposed suddenly to external radiation to increase its temperature until ignition occurs. The strength and geometrical placement of the pilot were chosen to minimize gas-phase induction time and heat feedback from the pilot to the fuel surface. Temperature measurements, flow visualization, and ignition delay time are used to characterize piloted ignition, and an existing one-dimensional heat transfer model is used to correlate the experimental results. Two different crude oils and SAE 3OW oil were used for these experiments. Crude oils were tested in their natural state and at different levels of weathering. It was observed that the ignition delay time is a strong function of the flow structures formed both in the liquid and gas above the pool. Piloted ignition is inhibited by premature boiling of the water sublayer, and weathering significantly increases the ignition delay time. It was determined that a critical heat flux for ignition could be obtained and better serve as a parameter to characterize the fuel propensity to ignite in the presence of a strong pilot. The minimum heat flux that will permit ignition before boiling of the water sublayer occurs also needs to be considered.