The Use of Exergy and Decomposition Techniques in the Development of Generic Analysis, and Optimization Methodologies Applicable to the Synthesis/Design of Aircraft/Aerospace Systems
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF MECHANICAL ENGINEERING
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In M.S. thesis 1, advantages of applying exergy-based analysis and optimization methods to the synthesisdesign and operation of aircraft systems is demonstrated using a supersonic aircraft fighter flown over an entire mission. A first set of optimizations involving four objectives two energy-based and two exergy-based are performed with only propulsion and environmental control subsystem degrees of freedom. Losses for the airframe subsystem are not incorporated into the two exergy-based objectives. The results show that, as expected, all four objectives globally produce the same optimum vehicle. A second set of optimizations is then performed with airframe degrees of freedom. However, this time one of the exergy-based objectives incorporates airframe losses directly into the objective. The results are that this latter objective produces a significantly better optimum vehicle. Thus, an exergy-based approach is not only able to pinpoint where the greatest inefficiencies in the system occur but seems to produce a superior optimum vehicle as well by accounting for irreversibility losses in subsystems only indirectly tied to fuel usage. No studies to date of which we are aware demonstrate the technology through an entire mission in which multiple flight conditions and constraints are encountered. Consequently, in M.S. theses 2 and 3, a formal Mach 6 through Mach 10 flight envelope is explored which includes cruise, accelerationclimb, decelerationdescend and turn mission segments. An exergy approach to the vehicle synthesisdesign, in which trade-offs between dissimilar technologies are observed, is proposed and measured against traditional energy-based methods of assessing highly integrated systems. The mission-level analysis provides much insight into the dynamics of mission-level hypersonic flight and demonstrates the usefulness of an exergy destruction minimization measure for highly integrated synthesisdesign.
- Research and Experimental Aircraft
- Unmanned Spacecraft