Konzept einer berührungslosen Lagerung für Rotations-Blutpumpen
A crucial challenge for the function of implantable blood pumps for long-term use is the hemocompatibility. Essentially, the mechanical damage of blood cells and the formation of blood clots have to be avoided. Therefore not only a well-guided blood flow alongside the pump has to be ensured, but also the rotor bearing has to be designed with special attention. In this thesis a concept of a contact-less rotor bearing for rotational blood pumps is developed. Following the standard engineering design processes, the boundary conditions for the use of miniature axial-flow pumps are defined and potential solutions are presented. After the evaluation of the principle solutions a hydrodynamic and/or magnetic bearing is proposed. The solution of a hybrid bearing implementing both principles is selected. However, the magnetic component is purely derived from the existing magnetic face coupling. Different embodiment variations of the hydrodynamic bearing are shown and discussed. The spiral groove bearing (SGB) yields the best results considering the given requirements. The theoretical background is outlined and a SGB is designed. Subsequently, the hydraulic performance of the bearing is assessed. Using flow visualisation techniques the flow within the grooves is analysed. Tracer particles show a fully developed velocity field. There is no acceleration of the flow within the grooves and the fluid moves evenly towards the centre. Computational fluid dynamics show pressure gradients, velocity vectors as well as shear stress distribution inside the SGB. A stationary vortex at the groove entrance is clearly visible. Hence, there is barely a fluid exchange between the bearing and its surroundings. A theoretical characterisation of the start-up behaviour on an ersatz-model provides information on the minimal gap width and the minimal rotational speed for a contact-less operation. Summary and discussion of the results conclude this thesis. Further studies are suggested in a final outloo
info:eu-repo/classification/ddc/620, Ingenieurwissenschaften, Lager, Spiralrillenlager, Blutpumpen
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