Spacecraft Thermal Design and Analysis

DURATION: THREE DAYS
COURSE NO.: 2130

As satellite design-lives are extended, and the power of communication equipment is increased, the problem of satellite thermal design becomes increasingly significant. Cost is now an overriding consideration, and system designs must be right the first time with little or no margin for error. It is imperative to define and understand the worst case parameters during the initial design phases of a program, in order to avoid unpleasant and costly changes later. The course presents the basic laws of conduction and radiation heat transfer, and illustrates how those laws apply to spacecraft. Boundary conditions, in terms of external fluxes and internal power dissipation, are introduced, and the means for obtaining temperature fields are discussed. Comparisons are made between finite differences and finite element methods of solution. Short cut, back of the envelope, and worse case approximations are emphasized so that approximate or limited results may be obtained early in a program. Active and passive hardware and/or design solutions are presented, and the advantages and disadvantages of various approaches are discussed. Actual satellite thermal design case studies are reviewed, and practical applications are emphasized.

COURSE MATERIALS:
Include extensive notes and the text "Satellite Thermal Control Handbook."

System analysts, program managers, project managers, power system engineers, test engineers, and all mechanical and aerospace structural engineers that do not have a detailed background in aerospace thermal analysis.

This course will provide an overall view of the means to design and analyze the thermal control of various types of satellites, from communication satellites in geosynchronous orbits to mini-satellites in low-Earth orbits. You will become acquainted with the hardware (such as heat pipes and pumped capillary loops) and surface coatings used. The industry standard software will be discussed as well as the use of the major finite element software, so that you will learn the limitations of these programs. Analytical case limit calculations will be emphasized so that scoping analyses may be performed.

1. Introduction and Overview.
   

   Satellite configurations. Types of orbits. Missions. Thermal environments.

2. Review of the Basic Laws of Heat Transfer.
   

   Conduction. How to utilize and extend the range of thermal conductivity. Problems and practice of contact conductance. Bolted joints. Electronic box installation.

3. Review of the Basic Laws of Heat Transfer.
   

   Radiation. Black body. Shape factors. Gray bodies. Enclosures. Spectral properties and the control of surface temperature. Surface properties of real surfaces. Angular dependence of surface properties. Partially-transmitting surfaces. Solar, albedo, and Earthshine spectra.

4. Energy Balances.
   

   Overall and detailed energy balances.

5. Thermal Modeling by Means of the Finite Difference Formulation and by Lumped Parameters.
   

   Conduction. Radiation.

6. Software.
   

   TRAYSYS for the generation of radiation shape factors and solar, albedo, and Earthshine incident and absorbed fluxes. Monte-Carlo methods and NEVADA. Detailed description of the most commonly-used software for the solution of thermal networks. Preprocessor description. Linear and nonlinear problems. Problem-dependent solution techniques. SINDA/G compared with SINDA-85. Solution of fluid networks. ESATAN and other similar programs.

7. Comparison of Finite Elements and Finite Differences.
   

   Limitations and advantages of the large finite element software packages such as NASTRAN, Algor and Cosmos. PC, work station, and main frame packages compared.

8. Passive Thermal Control Hardware.
   

   Surface finishes and tapes. Multilayer insulation. Heat sinks. Radiators. Fixed and variable conductance heat pipes. Phase change materials. Examples.

9. Active Thermal Control Hardware.
   

   Heaters. Fluid Loops. Thermo-Electrics. Examples.

10. Overall Design Concepts.
    

    Application to various types of satellites.