Recent Federal Aviation Administration research has illustrated that fuel tank inerting could be practical in the commercial fleet for the protection of center wing or body style tanks. The effect of pressure differences on the release of dissolved oxygen in a fuel load on an inert fuel tank ullage was studied. A test article was constructed and experiments were conducted to quantify the potential increase in oxygen concentration in an adjacent inert ullage as a result of gases in fuel during sea level stimulation, as well as at reduced atmospheric pressure. Different methods of stimulating the release of gases from the fuel were examined during laboratory experiments in an attempt to quantify the increase in oxygen concentration in an inert aircraft fuel tank ullage. This data was compared with flight test data in an attempt to gage the ability of laboratory tests and simple calculations to predict the resulting change in oxygen concentration of an inert commercial airplane fuel tank during a flight cycle. The oxygen evolution from different fuel loads was measured to determine the resulting oxygen concentration on an adjacent ullage. At sea level, the increase in oxygen concentration can be as great as 7 percent for an ullage inerted to 6 percent with an 80 percent fuel load that was stimulated. Increasing altitude allows for an additional increase in the oxygen concentration of the ullage even if the ullage was at equilibrium at sea level. Inerting the ullage through fuel has the effect of scrubbing the fuel to some rudimentary level of protection that reduces or eliminates the increase in oxygen concentration due to fuel air evolution, depending upon fuel load. Flight test data illustrated a relatively small amount of oxygen evolving from fuel compared to the theoretical amount available. Any effect of oxygen concentration increase due to fuel tended to be obscured by the more dominant effect of air entering the vent due to fuel consumption. Oxygen concentration flight test data with consumed fuel loads and inert ullages were best duplicated in laboratory experiments by not stimulating the fuel. Calculations of oxygen concentration increase have poor agreement with flight test data, but the flight test oxygen concentrations results fall within the band of 0 and 100 percent oxygen evolution.
Effect of Fuel on an Inert Ullage in a Commercial Transport Airplane Fuel Tank
2005
40 pages
Report
No indication
English