OBJECTIVES OF TRIPOD

There is a need for fast ship transportation that is both efficient and non-polluting. Conventional propellers are known to have a relatively low efficiency. As an indicative example, most of ship propellers installed on cargo vessels waste about 40 percent of the energy in the form of axial and rotational losses in the wake, vortex generation, noise production, cavitation, etc. The recovery of such losses is one of the major ways to contribute to a more rational, environmentally friendly use of energy.

The main objective of the TRIPOD project is the development and validation of a new propulsion concept for improved energy efficiency of ships. The ship propulsion efficiency will be optimized through the advanced combination of three existing propulsion technologies. In particular TRIPOD explores the feasibility of a novel propulsion concept resulting from the integration of two promising EU grown technologies (podded propulsion and tip loaded endplate propellers) in combination with energy recovery based on counter-rotating propeller (CRP) principle. The three existing technologies have been used separately and are known to improve the overall ship propulsion efficiency as compared to conventional propulsion. However, they have never been combined together in a single propulsion package.

TRIPOD contemplates two types of propulsive innovations, which will be tested for the first time:

  • Using CLT propellers in combination with PODs

  • Using CLT propellers in connection with CRP propulsion and with PODs

The methodology of work involves on the one hand model tests and on the other CFD methods.

As a result of the investigation tools will be developed to assess the optimal use of propulsive energy from environmental and economic viewpoints both for new designs and for the retrofitting of existing ships with the novel propulsion concept.

DEVELOPMENT OF TRIPOD PROJECT

Originally, the project was conceived for a scenario in which the entire propulsion unit was to be redefined, called later new building scenario. However, the ship-owner liked to know if a retrofit scenario would be profitable in which not only the hull but also the original propeller was to be maintained as part of the CRP unit. Then, during the first stages of the project the retrofitting scenario was defined. Two alternatives were selected with the aft POD propeller being either of conventional or CLT type. Then the study cases were set for three different retrofit alternatives as follows: CLT propeller alone instead of the original propeller, CRP case 1 with original main propeller & conventional POD propeller, and CRP case 2 with original main propeller & CLT POD propeller.

Finally, five model test programmes were established at two different ship draughts dealing the first three with the retrofit scenario and the last two with the new building scenario. In the new building scenario new propellers were designed and tested on an improved ship hull.

In the last part of the project the real economic criteria applied by a market leader are incorporated into the project. Elaborate procedures on how to determine yearly fuel savings and emission reductions based on the vessels operational profiles are applied and then the cost-benefit is assessed through a TCO (total cost of ownership) analysis.