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Aircraft Fuel Tank Inerting by Means of Fuel Cell Fuel Fogging
Final rept. 1 Jul 1968-Jan 1969
MCDONNELL AIRCRAFT CO ST LOUIS MO DESIGN ENGINEERING POWER AND FLUID SYSTEMSDEPT
Pagination or Media Count:
Inerting of aircraft fuel tanks to eliminate fires and explosions can be accomplished by a number of methods. Oxygen dilution with inert gases, flame arresting with open cell foam and chemical quenching using halogenated hydrocarbons are some of the more successful methods. Another approach, the subject of this report, is to maintain the ullage fuel rich by employing some of the liquid fuel itself in the form of a fog. The fuel fog system works on the principle that finely divided liquid fuel fog acts as if it were in the vapor state, adding to the natural fuel vapor concentration. The system consists of a distribution manifold with fog nozzles located to produce a uniform fog throughout the fuel cells under all degrees of ullage and dynamic flight conditions. Since the fuel itself is the inerting material weight, volume and logistic penalties are low. The first phase of the program was to define the fuel fog concentration and distribution with respect to various nozzle configurations, grouping and flow rates. Qualitatively, it was concluded that a uniform fog distribution is no problem due to the high turbulence observed in the visualization chamber. Ignition studies have defined the dynamic flammability zones for JP-4 using the most effective fog inerting nozzle with three ignition sources 14 joule capacitance spark, 23 joule induction spark, and incendiary, equivalent in weight and energy to a .50 caliber A.P.I. Pre- termination of the gunfire tests and the comparison of the subject system with other candidate systems was mutually agreed upon due to the limited inerting capabilities shown by the fuel fog system.
APPROVED FOR PUBLIC RELEASE