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Compressed natural gas (CNG) currently is used as an alternative fuel for internal combustion engines in motor vehicles. This paper presents results of an analysis of leaks from a model isolated section of CNG fuel system. Discharge of CNG was modeled as vent flow of a real gas hydrocarbon mixture through an orifice from a reservoir with finite volume. Pressures typically used in CNG fuel systems result in choked flow for gas venting directly to atmosphere, producing an under-expanded, momentum-dominated, turbulent free jet with well defined velocity and concentration fields. This paper presents results of analyses of reservoir pressure decay, and vent flow and concentrations fields for CNG venting from a pressurized reservoir into the atmosphere. A combination of empirically-derived analytical relationships and detailed two-dimensional high resolution computational fluid dynamic modeling was used to determine the velocity and concentrations fields of the resulting CNG jet.

A prototype fire suppression system was tested in one full-scale vehicle crash tests and three static vehicle fire tests. The prototype fire suppression system consisted of 2 Solid Propellant Gas Generators and two optical detectors. These components were installed on the hood of the test vehicle. A vehicle crash test and a series of static vehicle fire tests were performed to determine the effectiveness of this prototype fire suppression systems in extinguishing fires in the engine compartment of a crashed vehicle