This work addresses the development and optimization of propellers in particular of propeller-pumps used in cardiac support (left ventricular assist devices). A novel propeller design method is firstly validated for high-Re marine, multiblade propellers and is adapted afterward for designing small propeller-pumps used as left ventricular assist devices. The initial design framework (ADAP) is fully inverse for the case of marine propellers and is coupled with 3D CFD calculations. In addition, for marine propellers, a Blade Element Method (BEM) is developed for predicting off-design performance. The propeller designer can thus engage in a much faster goal-oriented design parameter search without the use of full 3D-CFD calculations. For the cardiac propeller-pump the design is performed both direct and inverse and has to be always accompanied by CFD simulations. The complexity of the flow around an encased propeller prevents the propeller designer from using BEM in this case. A propeller design framework (ADAP) with different radial momentum loss theories was developed in Matlab and validated against state of the art vortex-lattice methods. ADAP was programmed to write geometry data to grid generators (e.q. ANSYS TurboGrid) reducing the time needed from aerodynamic design to CFD simulation. It can also write structured data files which are needed for CAD systems for parametric generation of geometries. In the present work the interface was written for Creo. Instead of using only predefined NACA camber lines for the radial sections of propellers the framework is improved by implementing a novel method of computing thin airfoil cascades. This method is helpful in the case of designing propellers with more than 4 blades, where blade to blade effects are significant, as for example in the case of propellers used for large container ships. CFD results showed that by using the design code presented in this thesis the thrust of a 6 blades marine propeller was improved by 3.5% and was accompanied by a small propulsive ...