Fast Processes to Optimize Counter Rotating Propellers and Tip Rake Propellers
Dr.-Ing. Heinrich Streckwall, Hamburgische Schiffbau-Versuchsanstalt GmbH, Hamburg; Caroline Vielhaber, Technische Universität Hamburg-Harburg
In marine propulsion there may be various reasons to exclude a conventional propeller solution. Unconventional propulsion systems can promise to recover or prevent losses, which are considered inevitable if a conventional propeller would be installed. This energy saving aspect is supposed to drive the actual interests in Tip-Raked propellers. In some cases the conventional propeller may be excluded due to technical requirements. The specific request for an overall zero torque delivered by the propulsion system may lead to a Counter Rotating Propeller (CRP) -solution. Though CRP and Tip-Raked propeller are quite unique and distinct, the authors happened to work on both concepts very recently. This is the main reason to combine them in one contribution. In our presentation we introduce distinct processes, one suitable for CRP-design and the other considered capable to derive well performing Tip-Raked propellers. The outcome in both cases is a full blade geometry specification based on blade main data in combination with 2D blade section data. Searching for a proper foundation to define the shape of Tip-Raked propellers uniquely, we propose to retain the 2D section description and extend the conventional set of main data by two major columns.