Keywords

Apparent radiative property, Emissivity, Corrugated, V-groove, Spacecraft thermal control

Abstract

Spacecraft thermal control is entirely reliant upon radiative heat transfer with its surroundings for tem- perature regulation. Current methods are often static in nature and do not provide dynamic control of radiative heat transfer. As a result, modern spacecraft thermal control systems are typically ‘cold-biased’ with radiators that are larger than necessary for many operating conditions. Deploying a variable radiator as a thermal control technique in which the projected surface area can be adjusted to provide the appro- priate heat loss for a given condition can reduce unnecessary heat rejection and reduce power require- ments. However, the radiative behavior of the apparent surface representing the expanding/collapsing radiator changes in addition to the projected surface area size. This work experimentally quantifies the spectral, directional emissivity of an apparent surface comprised of a series of V-grooves (e.g. corrugated surface), as a function of angle and highlights its emission characteristics that trend toward black behav- ior. The experimental setup for quantifying this apparent radiative surface behavior is described and uti- lized to show the influence of surface geometry, direction and wavelength. Experiments on test samples were performed at 573 K. The experimental design is validated and demonstrated using fully oxidized, nearly diffuse, copper, corrugated test samples. The results presented in this work demonstrate, for the corrugated oxidized copper surfaces tested, that (1) higher emissivity values correspond to higher wave- lengths in the spectral range of 2.5 to 15.4 μm (2) apparent emissivity values increase with decreasing V-groove angle resulting in less spectral variation in emissivity and greater blackbody like behavior, (3) azimuth dependence can be relatively small despite the obvious pattern associated with a corrugated surface, and (4) as the V-groove angle decreases, higher emissivity values are associated with θ → 0◦ and φ → 0◦ . Results provide a foundation for future radiator design, improved spacecraft thermal control methods, and improved emissivity testing methods for patterned or angular surfaces.

Original Publication Citation

Meaker, K. S., Mofidipour, E., Jones, M. R., and Iverson, B. D., 2023, “Measured spectral, directional radiative behavior of corrugated surfaces,” International Journal of Heat and Mass Transfer. Vol. 202, p. 123745. DOI: 10.1016/j.ijheatmasstransfer.2022.123745

Document Type

Peer-Reviewed Article

Publication Date

2023-3

Publisher

International Journal of Heat and Mass Transfer

Language

English

College

Ira A. Fulton College of Engineering

Department

Mechanical Engineering

University Standing at Time of Publication

Associate Professor

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