Publication Date
2009
Document Type
Thesis
Committee Members
George Huang (Other), James Menart (Committee Member), Scott Thomas (Committee Chair), Joseph F. Thomas, Jr. (Other), Mitch Wolff (Committee Member), Kirk Yerkes (Committee Member)
Degree Name
Master of Science in Engineering (MSEgr)
Abstract
The objective of this thesis was to determine the feasibility of using loop heat pipes to dissipate waste heat from power electronics to the skin of a fighter aircraft and examine the performance characteristics of a titanium-water loop heat pipe under stationary and elevated acceleration fields. In the past, it has been found that the boundary condition at the condenser can be a controlling factor in the overall performance of this type of thermal management scheme. Therefore, the heat transfer removed from the aircraft skin has been determined by modeling the wing as a flat plate at zero-incidence as a function of the following parameters: airspeed: 0.8 ≤ Ma∞ ≤ 1.4; altitude: 0 ≤ H ≤ 22 km; wall temperature: 105 ≤ Tw ≤ 135°C. In addition, the effects of the variable properties of air have been taken into account. Heat transfer due to thermal radiation has been neglected in this analysis due to the low skin temperatures and high airspeeds up to Ma∞ = 1.4. It was observed that flight speed and altitude have a significant effect on the heat transfer abilities from the skin to ambient, with heat rejection becoming more difficult with increasing Mach number or decreasing altitude.
An experiment has been developed to examine operating characteristics of a titanium-water loop heat pipe (LHP) under stationary and elevated acceleration fields. The LHP was mounted on a 2.44 m diameter centrifuge table on edge with heat applied to the evaporator via a mica heater and heat rejected using a high-temperature polyalphaolefin coolant loop. The LHP was tested under the following parametric ranges: heat load at the evaporator: 100 ≤ Qin ≤ 600 W; heat load at the compensation chamber: 0 ≤ Qcc ≤ 50 W; radial acceleration: 0 ≤ ar ≤ 10 g. For stationary operation (az = 1.0 g, ar = 0 g), the LHP evaporative heat transfer coefficient decreased monotonically, thermal resistance decreased to a minimum then increased, and wall superheat increased monotonically. Heat input to the compensation chamber was found to increase the evaporative heat transfer coefficient and decrease thermal resistance for Qin = 500 W. Flow reversal in the LHP was found for some cases, which was likely due to vapor bubble formation in the primary wick. Operating the LHP in an elevated acceleration environment (az = 1.0 g, ar > 0 g) revealed dry-out conditions from Qin = 100 to 400 W and varying accelerations and the ability for the LHP to reprime after an acceleration event that induced dry-out. Evaporative heat transfer coefficient and thermal resistance was found not to be significantly dependent on radial acceleration. However, wall superheat was found to increase slightly with radial acceleration.
Page Count
158
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
2009
Copyright
Copyright 2009, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.
