Please use this identifier to cite or link to this item: http://dx.doi.org/10.18419/opus-12806
|Title:||Using URANS CFD to optimize the pitching motion and path of the cycloidal rotor blades|
|Abstract:||This master thesis describes the procedure for optimisation of the pitching and the trajectory for cyclorotor blades to increase the efficiency based on 2D CFD calculations. The open-source software OpenFOAM with URANS is used for these CFD analyses. Considering various numbers of blades (one to four), the use of the chimera technique is necessary using the built-in OpenFOAM solver overPimpleDyMFoam. B-splines describe the arbitrary pitching and trajectory implemented in separate OpenFOAM motion classes. Two possible modes of drive are investigated for the cycloidal system; ’constant velocity’ and ’constant angular velocity’. The Dakota toolkit performs the parametric optimisation with an evolutionary algorithm. A Python script initialises, monitors and evaluates each CFD case. Fourteen optimisation setups are carried out. An increase in the efficiency for each run is achieved. The main reason for the improvement is the better alignment of the blade forces to the global thrust. Another reason is that the optimised motion induces force peaks, which leads to an increase in thrust. The best result is captured for a four-blade case with a circular motion and a pitching path optimisation. The figure of merit is 0.758. Two further optimisation runs with higher Reynolds numbers are carried out for the two-blade case with a circular motion. Despite the pitching paths’ similarity, the figure of merit can be significantly increased (+8.8% for double Reynolds number and +17.7% for fourfold Reynolds number). Due to a false precalculation of the trajectory, the optimisation results for the ’constant angular velocity’ drive are invalid.|
|Appears in Collections:||06 Fakultät Luft- und Raumfahrttechnik und Geodäsie|
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