3. Electronic Theses and Dissertations (ETDs) - All submissions

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    Design and verification of a controlled induced mass flow system
    (2018) Saligram, Alesha
    The Medium Speed Wind Tunnel (MSWT) of the Aeronautic Systems Competency (ASC) within the Council for Scientific and Industrial Research (CSIR) performs majority static stability wind tunnel testing. The facility does not have an active inlet simulation capability, or a pressure system to support such a capability. Airframes with air breathing engines are tested with inlets either covered with fairings or left open to operate in a passive mode. To expand the wind tunnel offerings to include an inlet test capability, an active inlet flow induction and metering system was required. An ejector driven duct was designed to provide simulated engine air flow at rates and conditions appropriate for the MSWT size and operating envelope. Integral to the design was a mass flow metering system featuring a translating conical plug. To reduce the risk and size footprint the ejector unit comprised 14 ejectors clustered around a hollow central core housing the mass flow plug support and drive system. The ESDU 92042 software was utilised as the design tool to develop the ejector geometry and Computational Fluid Dynamics (CFD) was employed as a verification and off-design performance prediction tool. The entrained mass flow rate predicted by the CFD model for the 14-ejector unit exceeded the predicted entrained mass flow rate determined by the ESDU 92042 software. Experimental tests were performed to determine the actual entrained mass flow rate of a single ejector in order to verify the design predictions of the CFD model. The maximum entrained mass flow rate determined from the experiment is greater than the maximum entrained mass flow rate predicted by the CFD model. The CFD model over-predicts the entrained mass flow rates of the ejector in the sub-critical mode and will envisage it to under-predict the entrained mass flow rates in the critical mode. The experimental results for the single ejector suggest that the designed operating envelope predicted for the parallel arrangement of 14 ejectors should be reached.
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    Finite element analysis of compressible flows.
    (1995) Felthum, Luke T
    In this research a finite element analysis program was developed for the modelling of general compressible Euler flows. An explicit Taylor-Galerkin algorithm was used as the flow solver and was used in conjunction with a flux-corrected transport algorithm in order to obtain high shock resolution without numerical oscillations and overshoots. The solver was applied to two and three dimensional geometries. An axisymmetric extension of the Taylor Galerkin algorithm was also developed. For the two dimensional code, a fully automatic mesh generator was implemented which was able to generate meshes for completely arbitrary geometries, as well as an adaptive refinement algorithm which performs an error analysis on the solution and refines and coarsens the mesh appropriately in order to maintain an optimal mesh resolution. The automatic mesh generator dramatically reduced problem setup time and the adaptive refinement algorithm reduced compllter time by up to 90%" A number of test cases were performed covering a wide range of compressible flows including steady and unsteady flows in air, using the ideal gas model, and shocks in liquids, using the Tait model. Within the limitations of the inviscid and real gas assumptions made, accurate results were obtained,
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    Potential flows and transformation groups
    (2014-03-04) Pereira, Kevin Paul
    In this work we will consider the steady and two-dimensional potential flow of an incompressible fluid past a body without friction. Contrary to common experience, we will show that it is possible to calculate the Lie point symmetries that will leave the boundary value problem invariant. We are able to do this by solving the determining equation for the Lie point symmetries subject to a side condition. The side condition is a consequence of the boundary condition that occurs in the boundary value problem. We will show that solutions of the boundary value problem that were obtained previously using the method of conformal transformations are also group invariant solutions of the boundary value problem. We will also show that every group invariant solution of the boundary value problem can be used to generate new group invariant solutions of the same boundary value problem.
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