Integrated propulsion and power modeling for bimodal nuclear thermal rockets | Posted on:2008-04-03 | Degree:Ph.D | Type:Dissertation | University:University of Maryland, College Park | Candidate:Clough, Joshua | Full Text:PDF | GTID:1442390005457039 | Subject:Engineering | Abstract/Summary: | | Bimodal nuclear thermal rocket (BNTR) engines have been shown to reduce the weight of space vehicles to the Moon, Mars, and beyond by utilizing a common reactor for propulsion and power generation. These savings lead to reduced launch vehicle costs and/or increased mission safety and capability. Experimental work of the Rover/NERVA program demonstrated the feasibility of NTR systems for trajectories to Mars. Numerous recent studies have demonstrated the economic and performance benefits of BNTR operation.;Relatively little, however, is known about the reactor-level operation of a BNTR engine. The objective of this dissertation is to develop a numerical BNTR engine model in order to study the feasibility and component-level impact of utilizing a NERVA-derived reactor as a heat source for both propulsion and power. The primary contribution is to provide the first-of-its-kind model and analysis of a NERVA-derived BNTR engine.;Numerical component models have been modified and created for the NERVA reactor fuel elements and tie tubes, including 1-D coolant thermodynamics and radial thermal conduction with heat generation. A BNTR engine system model has been created in order to design and analyze an engine employing an expander-cycle nuclear rocket and Brayton cycle power generator using the same reactor.;Design point results show that a 316 MWt reactor produces a thrust and specific impulse of 66.6 kN and 917 s, respectively. The same reactor can be run at 73.8 kWt to produce the necessary 16.7 kW electric power with a Brayton cycle generator. This demonstrates the feasibility of BNTR operation with a NERVA-derived reactor but also indicates that the reactor control system must be able to operate with precision across a wide power range, and that the transient analysis of reactor decay heat merits future investigation.;Results also identify a significant reactor pressure-drop limitation during propulsion and power-generation operation that is caused by poor tie tube thermal conductivity. This leads to the conclusion that, while BNTR operation is possible with a NERVA-derived reactor, doing so requires careful consideration of the Brayton cycle design point and fuel element survivability. | Keywords/Search Tags: | BNTR, Thermal, Reactor, Nuclear, Power, Brayton cycle, Model | | Related items |
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