Design of a Microgravity Spray Cooling Experiment

Abstract

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information AFRL-PR-WP-TP-2006-240 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY ACRONYM(S) AFRL-PR-WP ABSTRACTAn analytical and experimental study was conducted for the application of spray cooling in a micro gravity and high-g environment. Experiments were carried out aboard the NASA KC-135 reduced gravity aircraft, which provided both the microgravity and high-g environments. In reduced gravity, surface tension flow was observed around the spray nozzle, due to unconstrained liquid in the test chamber and flow reversal at the heat source. A transient analytical model was developed to predict the temperature and the spray heat transfer coefficient within the heated region. Comparison of the experimental transient temperature variation with analytical results showed good agreement for low heat input values. The transient analysis also verified that thermal equilibrium within the heated region could be reached during the 20-25s reduced gravity portion of the flight profile. ABSTRACT An analytical and experimental study was conducted for the application of spray cooling in a microgravity and high-g environment. Experiments were carried out aboard the NASA KC-135 reduced gravity aircraft, which provided both the microgravity and high-g environments. In reduced gravity, surface tension flow was observed around the spray nozzle, due to unconstrained liquid in the test chamber and flow reversal at the heat source. A transient analytical model was developed to predict the temperature and the spray heat transfer coefficient within the heated region. SUBJECT TERMS

Interim Analysis of Iraqi Security Force Information Provided by the Department of Defense Report, Measuring Stability and Security in Iraq""

“…The test rig used for experimentation was very similar to that described by Baysinger et al (2004Baysinger et al ( , 2005, and Baysinger (2005). There were, however, a few main differences.…”

“…A system was designed by Baysinger et al (2004) to attempt to characterize a spray in variable gravity. A spray chamber was designed which included spray nozzles, heaters, and sumps to collect excess and condensed fluid.…”

Electromagnetic Control of High Heat-Flux Spray Impingement Boiling Under Microgravity Conditions

“…Kato et al (1994) also used orientation to simulate jig conditions, although they used a horizontal spray to simulate conditions of jig, and found data that was comparable to that of Yoshida et al A group at the Air Force Research Laboratory, Propulsion Directorate, Power Division (AFRL/PRPS) under the direction of Dr. Kirk L. Yerkes has been investigating the ability of spray impingement boiling to achieve higher heat transfer performance in a space and weight efficient manner under conditions of variable gravity. Baysinger et al (2004) and Yerkes et al (2006) describe the AFRL experiment, which has been flown several times on NASA variable gravity research aircraft. From its inception, the present (WVU) investigation of electrical body forces in spray impingement boiling has been closely coordinated with AFRL so as to complement and extend the non-electrical AFRL research.…”

“…The spray droplet Reynolds, Weber, and capillary numbers have been computed (Hunnell, 2005) based on FC-72 liquid properties and the droplet diameter and velocity measurements obtained by Baysinger et al (2004) for an identical spray nozzle. Weber and Reynolds numbers were 1140 and 1650 respectively.…”

Investigation of Enhanced Surface Spray Cooling

“…6.1). Thermal management of flight system components such as (Golliher et al, 2005), design and flight of KC-135 microgravity airplane test apparatus Baysinger et al, 2004;Hunnell et al, 2006), and computer modeling tailored for the relevant environment . This research is expected to continue and grow over the upcoming years.…”