Basic experimental studies of the injection of liquid fuel into a two dimensional flowfield designed to represent a sudden-expansion "dump" combustor were performed under cold-flow conditions. Test conditions were as follows: 0.6 entrance Mach number, 25 PSIA total pressure, and nominally 75°F stagnation temperature. Two step heights were investigated, 1.0 in. and 0.5 in., corresponding to area ratios of 1.33 and 1.17. The investigation included Pitot and static pressure distributions, spark and streak shadowgraphs, surface flow visualization, direct photographs and videotape recordings. The backlighted streak and spark shadowgraphs were used to obtain jet penetration and break-up information. Oil drop surface flow studies showed details of the flow in the recirculation region behind the step. The injectant for these cold flow studies was selected as water, which was injected transversely to the air flow 1.0 in. and 0.5 in. upstream of the step at various flow rates. It was found that both the location of the injection port relative to the step and the step height had no measurable effect on jet penetration and break-up. Injectant accumulation on the combustor wall in the base-flow region was found to be substantial under some conditions, and the amount of accumulation was shown to be a strong function of initial liquid jet penetration height. / M.S.

In this thesis, a simple moving boundary technique has been suggested, implemented and verified. The technique may be considered as a generalization of the well-known "ghost" cell approach for boundary condition implementation. According to the proposed idea, the moving body does not appear on the computational grid and is allowed to move over the grid. The impermeable wall boundary condition is enforced by assigning proper gasdynamic values at the grid nodes located inside the moving body close to its boundaries (ghost nodes). The reflection principle taking into account the velocity of the boundaries assigns values at the ghost nodes. The new method does not impose any particular restrictions on the geometry, deformation and law of motion of the moving body. / The developed technique is rather general and can be used with virtually any finite-volume or finite-difference scheme, since the modifications of the schemes themselves are not required. In the present study the proposed technique has been incorporated into a one-dimensional non-adaptive Euler code and a two-dimensional locally adaptive unstructured Euler code. / It is shown that the new approach is conservative with the order of approximation near the moving boundaries. To reduce the conservation error, it is beneficial to use the method in conjunction with local grid adaptation. / The technique is verified for a number of one and two dimensional test cases with analytical solutions. It is applied to the problem of supersonic inlet starting via variable geometry approach. At first, a classical starting technique of changing exit area by a moving wedge is numerically simulated. Then, the feasibility of some novel ideas such as a collapsing frontal body and "tractor-rocket" are explored.

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