RESEARCH ON COMBINED CYCLE ENGINES FOR SUPER AND HYPERSONIC AEROSPACE PROPULSION

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Supersonic Through-Flow Fan (STFF) Aerodvnamics : Parametric studies of the cascade flutter boundaries have been conducted by using the newly developed CFD and Double Linearization Theory codes. The usefulness of the latter code has been confirmed. The start and unstart conditions of STFF cascade flows have been investigated by N-S code numerical simulation. The flow field has been studied by means of the flow visualization.Chemically Reacting Flows : A plasma torch system has been constructed. The effect of active chemical species on initiating the hydrogen combustion in supersonic air flows has been theoretically and experimentally verified. the conditions of generating and controlling the precombustion shock for holding flames in a supersonic air flow mixed with a low-reacting fuel gas have been experimentally investigated by using Mie-scattering and OH emission measurement techniques. A new computational model to predict NOx concentrations in turbulent diffusion combustion has been developedMixing : Three-dimensional structures of concentration, velocity and vorticity fields generated by a lobed plate mixer have been experimentally studied. The behavior and role of vortices in mixing phenomena have been theoretically investigated.Shock Wave : The mechanism of unstable shock motion in cascade has been numerically studied.Material : A residual stress reduction technique by modifying the surface geometry has been proposed to prevent cracks from developing in the coated layr due to thermal stress and its usefulness has been theoretically verified.