Vincekovic, Luka (2022) Multidisciplinary Optimisation of High Pressure Turbine Blade Tips. PhD thesis, University of Sheffield.
Abstract
High pressure turbines are characterised by increasing turbine entry temperatures and unshrouded rotor blades, resulting in thermal stresses at the turbine blades due to elevated heat load. Removal of the shroud improves turbine performance by allowing over tip leakage flow driven by the turbine propulsive pressure gradient. This thesis discusses the multidisciplinary optimisation of high pressure turbine blade tips, where both heat load and turbine performance are assessed simultaneously. Optimising winglet tips, the thesis shows that by using a locally corrected heat transfer coefficient, good representation of heat load can be achieved taking into account the change of local flow with wall temperature. Focusing on the tip leakage, performance losses are identified, and their changes are analysed for a set of selected winglet tips. It is presented that winglet tips have a great potential for increasing the stage efficiency through the tip leakage mass flow and shearing losses reduction. By utilising a design space defined through the use of the radial basis function surfaces, the thesis demonstrates that both topology and in-topology shape optimisation can be simultaneously performed. Because of the non-linearity of the design space, conventional gradient based methods are shown to struggle regressing a design space and finding an optimum. To resolve that, approach using subdivision of design space has been examined. Novel response surface method that uses artificial neural networks is also successfully applied to this kind of a design space. Finally, the thesis provides results of genetic based optimisation and Pareto front has been generated and analysed. Discussion shows that treating a turbine tip optimisation as a topology problem can significantly increase the range of a potential improvement, both aerodynamically and in the terms of heat load.
Metadata
Supervisors: | Qin, Ning |
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Keywords: | high pressure turbine, high pressure turbine tips, topology optimisation |
Awarding institution: | University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Mechanical Engineering (Sheffield) |
Identification Number/EthosID: | uk.bl.ethos.879588 |
Depositing User: | Luka Vincekovic |
Date Deposited: | 09 May 2023 09:54 |
Last Modified: | 01 Jun 2023 09:53 |
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