by Moustafa Abdel-Maksoud and Hans-Jürgen Heinke, SVA Potsdam
Nozzle propellers are used in many types of ships and for dynamic positioning of platforms. Their operation at high thrust loadings and low inflow velocities requires high-tech designs. SVA Potsdam specializes in these propulsion systems and is investing in continuous research to ensure that its designs meet expectations.
The flow in the gap between the propeller tip and the inside wall of the nozzle strongly influences the performance of the propeller, and the greater the thrust loadings, the greater the influence. CFD allows visualization of these flows, which are difficult to study experimentally because the gap can be less than one millimeter. Unfortunately, the required computational effort increases rapidly as the thrust loading increases (due to slower convergence as the rotational speed of the propeller increases), and we have realized that combining experimental and numerical investigations can overcome the shortcomings of each method. The experimental data provide a good overview of the forces and moments for the whole range of operational conditions, while CFD reveals the detail of the flow for selected loadings.