This work presents the aerodynamic topology optimisation of high pressure turbine rotor blade tips. Before carrying out the topology optimisation on the blade tip, some initial tip design studies were carried out. A winglet tip was optimised first and it was found that the optimum winglet design features a combination of small and largest overhangs possible that increase the aerodynamic efficiency by 1.40% compared to the datum design. Secondly, a radial basis function based parametrisation was set up to allow the creation of a single squealer rim on the datum blade's tip that could move position in the circumferential direction. The optimum case proved to increase efficiency by 0.46% compared to the flat datum tip of the same tip gap. After that, a combination of winglet and topology free squealer tips was investigated via topology optimisation. The winglet tip was created as in the winglet only optimisation cases and topology free squealer walls were parametrized and created using mapping of a radial basis function surface. It was shown that the radial basis function surface based parametrization creates a very flexible design space containing novel squealer topologies. Combining both winglet and novel squealer topology optimisation, better designs than the flat tip winglet can be achieved. However, because of the flexibility of the design space, gradient based methods were found to struggle to reach an optimum solution. This was resolved by optimising in the most promising design subspace.

This work presents the aerodynamic topology optimisation of high pressure turbine rotor blade tips. Before carrying out the topology optimisation on the blade tip, some initial tip design studies were carried out. The winglet shape was optimised using two different design space setups and parameter limits. The optimum winglet design features the largest overhangs and in the case of unconstrained optimisation proved to have 1.40% greater aerodynamic efficiency. Secondly, a radial basis function based parametrisation was set up to allow the creation of single squealer line using the flat tip blade as a baseline geometry. The optimum case proved to increase efficiency 0.46% compared to the flat tip. After that, a combination of winglet and topology free squealer tips was investigated for topology optimisation. The winglet tip was parametrized as in the winglet only optimisation cases and topology free squealer walls were created using mapping of radial basis function surfaces of different complexities. It is shown that by combining both winglet and novel squealer topology optimisation, better designs of different topologies can be produced.

This work deals with aerodynamic and aerothermal optimisations of high pressure turbine blade tips where a winglet turbine tip is optimised in terms of both aerodynamic efficiency and integrated heat transfer coefficient. Two constraints were introduced in the optimisation process. In particular, turbine mass flow, defined as a non-dimensional turbine inlet capacity, and stage reaction were constrained to change for up to ±0.5% from the datum values. Turbine inlet capacity and stage reaction constraints were achieved by skewing the rotor blade of turbine stage. Steady RANS simulations with k-𝜔 SST turbulence model were performed for the turbine stage using multi-block fully structured mesh and a mixing plane between the stator and the rotor domain. Gradient based optimiser was used in all the optimisations performed. Aerodynamic optimisation was performed first, with and without the constraints, followed by multidisciplinary optimisation done in three steps. By varying the objective weights to explore the Pareto front, winglet designs with considerable efficiency improvements for only minor increase in heat load were identified, featuring sharp leading edge and suction side overhangs. On the other hand, sharp edges were found to be prone to local aerodynamic heating, highlighting the importance of the aerothermal assessment of this problem.

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