Showing papers on "Ullage published in 1969"
01 Sep 1969
TL;DR: In this paper, a ramp pressurization test was conducted with gaseous helium in a thick-walled liquid hydrogen tank with the shape and approximate volume of a Centaur liquid hydrogen flight vehicle tank.
Abstract: Ramp pressurization tests were conducted with gaseous helium in a thick-walled liquid hydrogen tank with the shape and approximate volume of a Centaur liquid hydrogen flight vehicle tank. The helium requirements were obtained at two pressure levels above liquid hydrogen saturation pressure, at four tank ullages, and for various ramp times. For all except small ullages there was good agreement between the experimentally determined helium requirements and the requirements predicted by an analytical program developed at the Lewis Research Center.
10 citations
01 May 1969
TL;DR: In this article, a fuel fog system is proposed to maintain the ullage fuel rich by employing some of the liquid fuel itself in the form of a fog, which acts as if it were in the vapor state, adding to the natural fuel vapor concentration.
Abstract: : 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.
2 citations
TL;DR: This long, continuous, high-velocity fluorine injection probably created a hole in the Z/H2 that reached from the injector to the ullage along the tank centerline, which could explain the fact that efficiency remained uniform and high.
Abstract: rate, fluorine injection. Long prepressurization times (23 sec) were required to reach 100 psig, and this long, continuous, high-velocity fluorine injection probably created a hole in the Z/H2 that reached from the injector to the ullage along the tank centerline. The vapor in this ullage extension was heated by injection in the same way that US mode injection heats the ullage, which gave a high initial pressurization efficiency that is comparable to that of the US mode. Further, at this high tank pressure, the LH2 outflow rate was quite high, so that the drain from an ullage fraction of 44-78% (shown as the straight solid line) took place in only 6.6 sec. This short time gives little opportunity for heat transfer and could explain the fact that efficiency remained uniform and high. Again, with large ullage volume (and empty tank), all of the injection modes tend to an efficiency value of about 50% of the ullage heating prediction.
1 citations