Accession Number:

ADA506284

Title:

The Effect of Variable Gravity on the Cooling Performance of a Partially-Confined FC-72 Spray

Descriptive Note:

Interim rept. 14 Sep 2004-5 Jun 2009

Corporate Author:

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE

Report Date:

2009-07-01

Pagination or Media Count:

214.0

Abstract:

This thesis discusses the effects of a variable-gravity environment on the performance of a subcooled partially-confined spray. An experiment, consisting of a test chamber, the associated flow loops, and instrumentation, was fabricated and flown on the NASA Reduced-Gravity Testing Platform. This modified KC-135 aircraft followed a parabolic flight path to provide various acceleration levels. The spray chamber contained two opposing nozzles spraying onto Thick Film Resistor TFR heaters, which were mounted on insulating glass pedestals. Only the upward facing heater was used during this testing. Thermocouples under the heater in the glass pedestal were used to determine the heater surface temperature. The glass pedestals were surrounded by an annular sump system, which was used to collect and remove the cooling fluid from the test chamber. The fluid used for this testing was FC-72, which is a non-toxic, non-flammable, and non-reactive refrigerant. Due to its dielectric nature, FC-72 was sprayed directly onto the electric thick film heaters. The parametric ranges of this experiment were as follows Heat flux to the spray, 21.1 less than or equal to qsp less than or equal to 69.0 Wattssquare centimeter acceleration field, 0.15 less than or equal to a less than or equal to 1.80 grams coolant volumetric flow rate, 6.18 less than or equal to V less than or equal to 8.94 milliliterssecond and coolant subcooling, 23.1 less than or equal to delta-Tsub sc less than or equal to 31.7 degrees Kelvin. The heat fluxes tested were below the critical heat flux qCHF. The wall superheat delta-Tsub sat Tsub s - Tsub sat was found to increase with heat input and acceleration, and decrease with subcooling and volumetric flow rate.

Subject Categories:

  • Miscellaneous Materials
  • Test Facilities, Equipment and Methods
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE