Mass Loading Effects on Fuel Vapor Concentrations in an Aircraft Fuel Tank Ullage

摘要

This report discusses experiments performed within a simulated fuel tank211u001eapproximately 1/20 the size of a typical B-747 center wing fuel tank (CWT). The 211u001evapors generated within the ullage of this tank were analyzed under different 211u001emass loadings in an effort to determine the effects of the mass loading and fuel 211u001edistribution. It was determined from these tests that in order to have a 211u001esubstantial effect on the flammability of the vapor within the CWT, the mass 211u001eloading would have to be somewhere between 0.08 and 0.15 kg/cu m. A substantial 211u001eeffect was defined as a minimum 20% decrease in the maximum hydrocarbon count 211u001ewhen compared to the average of all tests conducted with larger mass loadings. In 211u001eaddition, it was found that while the distribution of the fuel has no effect on 211u001ethe peak flammability (vapor composition) that is reached, it does have a 211u001esignificant effect on how long it takes to reach the final state. The less 211u001edispersed the liquid fuel is, the longer it will take the vapor to reach its 211u001emaximum flammability point.