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Aircraft Thermal Management Using Loop Heat Pipes

Fleming, Andrew J.

Abstract Details

2009, Master of Science in Engineering (MSEgr), Wright State University, Mechanical Engineering.

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.

Scott Thomas, PhD (Committee Chair)
Kirk Yerkes, PhD (Committee Member)
Mitch Wolff, PhD (Committee Member)
James Menart, PhD (Committee Member)
George Huang, PE, PhD (Other)
Joseph F. Thomas, Jr., PhD (Other)
158 p.

Recommended Citations

Citations

  • Fleming, A. J. (2009). Aircraft Thermal Management Using Loop Heat Pipes [Master's thesis, Wright State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=wright1238086423

    APA Style (7th edition)

  • Fleming, Andrew. Aircraft Thermal Management Using Loop Heat Pipes. 2009. Wright State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=wright1238086423.

    MLA Style (8th edition)

  • Fleming, Andrew. "Aircraft Thermal Management Using Loop Heat Pipes." Master's thesis, Wright State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1238086423

    Chicago Manual of Style (17th edition)