Vaporization of JP-8 Jet Fuel in a Simulated Aircraft Fuel Tank ...

pump that could draw samples from altitudes as high as 35,000 feet. However, when
sampling from altitudes lower than 35,000 feet, the pump would draw more than the
necessary amount required by the FID, which would just be wasted by dumping into the
laboratory air. Also, by drawing a continuous sample at a high flow rate, hydrocarbon-
free air would be drawn in to the ullage through the vents, which would dilute the sample
and cause the FID readings to be false. It was for these reasons that an intermittent
sampling method was devised for tests to be performed at sub-atmospheric pressures.
The FID had a very high response time of 0.2 seconds, so a sample time of 30 seconds
every ten minutes was agreed upon taking into consideration the analyzer response time,
the flow rate of the sample pump and the length of the sample lines.
4.2 Flight Profiles
A flight profile is the temporal pressure and temperature variation for the duration of the
test. Before a flight profile test was run the fuel was loaded into the tank and allowed to
equilibrate. A flight scenario was created that simulated an airplane on the ground for
about an hour at ambient sea level temperature and pressure with heating of the fuel tank
to about 30°F above the initial liquid temperature. Quasi-steady equilibrium was attained
after about an hour, then the airplane began ascent at 1,000 feet per minute until the
cruising altitude was reached. The airplane would cruise at altitude for an hour then
begin decent at –1,000 feet per minute. The test was complete after the airplane was back
on the ground. Ambient temperatures at high altitudes were obtained from Unisys
weather constant height plots. Ambient temperatures of 20°F, -10°F, and -50°F were
used at altitudes of 10,000 feet, 20,000 feet, and 30,000 feet, respectively. A linear
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