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

Temperature, Deg. F.
40
35
30
25
20
15
10
5
0
Thermocouple
Error
FID Error
Fuel Temp
Measured THC
Calculated THC
0 1000 2000 3000 4000 5000 6000
Time, seconds
Figure 5.5. Isooctane fuel vaporization at atmospheric pressure and reduced ambient temperature,
M.L.=31.5 kg/m 3 .
5.2 JP-8 Tests at Constant Ambient Pressure
5.2.1 Atmospheric Pressure
Figures 5.6 and 5.7 show experimental and computed results at constant (atmospheric)
pressure, for two tests with similar liquid fuel heating profiles. As was previously
mentioned, the computed results were for two different fuel compositions (115°F and
120°F flashpoint from ref [21]) with flashpoints bracketing the measured test fuel
flashpoint of 117°F. There was good agreement between experimental and calculated
results, as the calculated ullage vapor concentrations using the two different fuel
compositions bracketed the measured ullage vapor concentration. Likewise, figure 5.8
shows the results from the intermittent sampling test. Good agreement is again found
between the calculated and measured ullage vapor concentrations.
It was necessary to compare the methods to determine if intermittent sampling
could be used in the place of continuous sampling when necessary; i.e., at simulated high
altitudes. Unfortunately, the comparison of the two methods couldn’t be performed at
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
% Propane Equivalent
37