Browsing by Author "Tunstall, Richard J."

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    An enhanced compressor sub-idle map generation method
    (Global Power and Propulsion Society, 2018-01-13) Ferrer-Vidal, Luis E.; Pachidis, Vassilios; Tunstall, Richard J.
    Several techniques have come about for the mathematical extrapolation of compressor maps from the idle region down to zero speed. Relatively little work has been done on methods which attempt to extract compressor sub - idle performance from physical grounds. This paper focuses on the design of an axial compressor rig to obtain sub - idle data in the form of locked rotor and windmill characteristics. The rig design is presented and the results obtained discussed. The data gathered is used to generate physics - based sub - idle compressor maps which are then compared to existing method s for sub - idle map generation. Interpolation from the locked rotor characteristic is shown to improve map generation over extrapolation methodologies, while the windmilling characteristic is shown to be an important addition to the interpolation process.
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    ItemOpen Access
    Generating axial compressor maps to zero speed
    (SAGE, 2020-12-06) Ferrer-Vidal, Luis E.; Pachidis, Vassilios; Tunstall, Richard J.
    Gas turbine performance models typically rely on component maps to characterize engine component performance throughout the operational regime. For the sub-idle case, the lack of reliable rig test data or inability to run design codes far from design conditions entails that component maps have to be generated from the extrapolation of existing data at higher speeds. This undermines the accuracy of whole-engine sub-idle performance models, at times impacting engine development and certification of aviation engines and the accuracy of start-up performance prediction in industrial gas turbines. One of the main components driving this issue is the core compression system, which can present operability concerns during light-up and which also sets the combustor airflow required for ignition. This paper presents, discusses, and draws on previous approaches to describe a method enabling the creation of sub-idle compressor maps from analytical and physical grounds. The method relies on the calculation of zero-speed and torque-free lines to generate a map down to zero speed along with analytical interpolation. A method for the interpolation process is described. A sensitivity study is carried out to assess the effects that different elements of the map generation process may have on the accuracy of the resulting performance calculation. Overall, a method for the generation of accurate, consistent maps from limited geometry data is identified.