Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 71-72). Also available via the Internet.

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Supersonic inlet starting by mass spillage is studied theoretically and numerically in the present thesis. A quasi-one-dimensional, quasi-steady theory is developed for the analysis of flow inside a perforated inlet. The theory results in closed-form relations applicable to flow starting by the mass spillage technique in supersonic and hypersonic inlets. / The theory involves three parameters to incorporate the multi-dimensional nature of mass spillage through a wall perforation. Mass spillage through an individual slot is studied to determine these parameters; analytical expressions for these parameters are derived for both subsonic and supersonic flow conditions. In the case of mass spillage from supersonic flows, the relations are exact. However, due to the complexity of flow field, the theory is an approximation for subsonic flows. Therefore, a correction factor is introduced which is determined from an empirical relation obtained from numerical simulations. / A methodology is also proposed to determine perforation size and distribution to achieve flow starting for a given inlet at a desired free-stream Mach number. The problem of shock stability inside a perforated inlet designed with the proposed method is also discussed. / The method is demonstrated for some test cases. Time-realistic CFD simulations and experimental results in the literature confirm the accuracy of the theory and the reliability of the proposed design methodology.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "August, 2006." Includes bibliographical references. Online version available on the World Wide Web.

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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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Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 6 uppsatser.

Homogeneously charged spark ignition (SI) engines are unable to stabilise the combustion in ultra lean mixtures, therefore they operate with a near stoichiometric air-fuel ratio (AFR) at all load points. This produces high engine out NOx and CO emissions with a compromise on fuel consumption. Moreover, stoichiometric operation is needed for effective operation of a three way catalyst, which is not adequate to meet future fuel consumption targets. (For complete abstract open document)