Internship: “Scaling effects on the performance of stern flaps for displacement ships”

Internship: “Scaling effects on the performance of stern flaps for displacement ships”

  • Stage / Internship
  • Wageningen
Scaling effects on the performance of stern flaps for displacement ships 

For MARIN Academy we are looking for a student for the following internship:

A stern flap is an extension of the hull bottom aft of the transom, usually at a small angle with the aft ship buttocks. Stern flaps are often applied on (naval) displacement ships to increase the maximum speed or to reduce the power required at the design speed. In some recent tank projects, stern flaps were optimised for fuel consumption, taking into account the operational profile of the ship. As a result, the flaps were also tested at the relatively low cruising speeds. The flaps are believed to have a detrimental effect on the propulsive performance at these speeds, which is confirmed by the model test results.

However, published sea trial results and recent CFD calculations at MARIN show a significant scaling effect on the stern flap performance in the lower speed range. At lower speeds the full scale performance of the stern flaps seems to be significantly more favourable compared to the model scale performance.

These results raise some interesting questions. Do we select the right stern flap, when we select the most fuel-saving stern flap based on model test results? And if model tests show that a stern flap is not beneficial for the overall fuel consumption due to the penalty at lower speeds, is the decision to omit the stern flap correct?

Further investigation of the scaling effects on stern flaps performance is required to answer such questions. In this internship you will therefore investigate this scaling effect by performing CFD calculations on a number of hull forms with our in-house viscous flow code ReFRESCO for both model and full scale. The results of these calculations will be compared to the results of model tests.

 Stern flap on a MARIN ship model

The main objective of the internship is to investigate the differences in performance on model and full scale, with a particular interest for the lower cruising speed. A secondary objective is to investigate where these differences, if any, originate from.
The internship is for the duration of about 3-4 months. Both the starting date and the duration can be adapted in consultation with the supervisor.
The profile
We are looking for an enthusiastic student who is willing to learn ReFRESCO and its post-processing tools. You are expected to have an investigative mindset and knowledge of hydromechanics.
Department and supervisor
During the internship you will be connected with the department Ships of MARIN in Wageningen. The supervisor for this internship, Marino Nieuwhof, is working as Project Manager at the Ships Department.

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