This dissertation is focused on a numerical framework for time-accurate solutions of high-speed unsteady flows with applications to flows of a Pulse Detonation Engine (PDE). The space-time Conservation Element and Solution Element (CESE) method employed is a novel numerical method for time-accurate solutions of nonlinear hyperbolic equations. As a part of the present result, a suite of two- and three-dimensional CESE codes has been developed. The computer codes are fully parallelized based on domain decomposition with Message Passing Interface (MPI) for data communication. The codes have been applied to analyze various flow fields of the PDE concept. First, numerical results of one-, two- and three-dimensional detonation waves are reported. The chemical reactions were modeled by a one-step, finite-rate, irreversible global reaction. The classical Zeldovich, von Neumann, and Doering (ZND) analytical solution was used to set up the initial conditions as well as for code validation. In the three-dimensional calculations, detonations in square, round, and annular tubes at different sizes were successfully simulated. Salient features of detonation waves were crisply resolved. Second, as a promising detonation initiation means, implosion with shock focusing was investigated. In two-dimensional calculations, we found a double-implosion mechanism in a successful detonation initiation process. Third, the plume dynamics of a PDE fueled by propane/air mixtures were studied to support the prototype development at NASA Glenn Research Center (GRC). Numerical results show that in each PDE cycle the engine is actively producing thrust forces only in about 6% of one cycle time period. The rest of the time is occupied by the blow-down and refueling processes. Since the PDE tube is always open, the processes depend on the flow conditions outside the PDE tube. In the near-field plume, complex shock/shock and shock/vortex interactions were found. In the far field, a spherical expansion wave is the dominant flow feature. This dissertation work is synergy of a very accurate and efficient CFD method, i.e., the CESE method, and the modern parallel computing technology. This approach could point to a new direction for high-fidelity simulations of complex flow fields of advanced propulsion systems.
|School:||The Ohio State University|
|School Location:||United States -- Ohio|
|Source:||DAI-B 79/09(E), Dissertation Abstracts International|
|Keywords:||Computational fluid dynamics, Detonation, Numerical simulation, Parallel computing, Pulse detonation engine, The cese method|
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