Combined thermal protection and thermal propulsion for aerogravity assist missions
- The gravity assist maneuver is a way for spacecraft to gain or lose speed without expending any propellant. This technique is an extremely important and commonly used tool in the mission planner's toolbox, and enables some missions that would be impractical to do purely propulsively. Aerogravity assist is an enhanced version of the gravity assist that uses aerodynamic lift in addition to gravity to further increase the momentum exchanged in these maneuvers. It shows significant possible benefits in reducing mission time of flight, lengthening launch windows, and reducing the size (and therefore cost) of launch vehicle required. However, atmospheric flight at interplanetary speeds poses major obstacles, with aerothermal heating and drag loss being two of the most prominent. In the aerogravity assist literature, heating is usually addressed by limiting flight speed to allow use of a radiatively cooled leading edge. Drag loss is addressed by optimizing the vehicle's aerodynamic shape (usually by using a waverider configuration, which is a class of aerodynamic shapes specially designed for hypersonic flight). Both flight speed limitations and achievable waverider lift to drag ratios are important constraints on aerogravity assist. The thermal aerogravity assist concept introduced in this dissertation addresses both problems with a single combined system that turns the heating problem into a solution for the drag loss problem. An active cooling system with a flowing coolant is used to absorb the heat produced by atmospheric entry, allowing the vehicle to withstand higher heat fluxes and permitting faster flight speeds. The heated coolant is then re-used in a thermal propulsion system that makes up for drag losses. The first part of this work is a feasibility study of this thermal aerogravity assist concept, and ends with an example design for a mission to match Voyager 1's solar system escape velocity with a much larger spacecraft (3200 kg compared to Voyager 1's 930 kg) while still using the same launch vehicle. This is intended to illustrate the possibilities of the concept and provide a starting point for future analyses. The second part discusses the design, fabrication, and testing in a miniature arcjet facility of a new kind of actively cooled leading edge that was inspired by the particular demands of thermal aerogravity assist. This leading edge cooling concept takes advantage of the unique thermal properties of highly oriented pyrolytic graphite (HOPG) and the exceptional heat removal capabilities of jet impingement cooling. Both thermal aerogravity assist and the HOPG leading edge concept are novel contributions to the field.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Murakami, David Daisuke
|Stanford University, Department of Aeronautics and Astronautics.
|Alonso, Juan José, 1968-
|Alonso, Juan José, 1968-
|Statement of responsibility
|David Daisuke Murakami.
|Submitted to the Department of Aeronautics and Astronautics.
|Thesis (Ph.D.)--Stanford University, 2016.
- © 2016 by David Daisuke Murakami
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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