| 1. |
|
|
| 2. |
- Allenström, Björn, et al.
(författare)
-
Amplification of ship generated wake wash due to coastal effects
- 2003
-
Ingår i: Transactions - Society of Naval Architects and Marine Engineers. - 0081-1661. ; 111, s. 61-77
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper discusses the results from extensive wake wash measurements carried out with a model of a ROPAX ship passing a bay. The tests were carried out in SSPA 's sea-keeping and maneuvering basin. This model had been subjected to wash wave measurements in open water in previous tests, which gave possibilities for comparisons between restricted and unrestricted waters'. Six wave gauges were placed inside and outside the bay, and a significant drawdown was noticed in addition to amplifications of the Kelvin waves. The drawdown and the Kelvin waves that occurred in the bay are difficult to explain, but this paper makes an attempt to analyze the phenomena that occur. The different wave theories that can be used in this case are presented The methods that are used for analyzing the measured signals are described One conclusion that can be made is that drawdown caused by the Bernoulli wave can probably be considered a worse problem than ordinary wash waves (Kelvin waves) in restricted and especially shallow waters when looking at large displacement ships.
|
|
| 3. |
- Allenström, Björn, et al.
(författare)
-
Determination of wetted surface
- 2009
-
Ingår i: AMT’09 – 1st Int Conference on Advanced Model Measurement Technology for EU Maritime Industry, Nantes, 1-2 sept 2009.
-
Konferensbidrag (refereegranskat)
|
|
| 4. |
- Ran, Heng, 1981, et al.
(författare)
-
Auxiliary Kite Propulsion Contribution to Ship Thrust
- 2013
-
Ingår i: ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2013; Nantes; France; 9 June 2013 through 14 June 2013. - 9780791855423 ; 8
-
Konferensbidrag (refereegranskat)abstract
- Low speed transportation is more energy efficient than high speed transportation in general. Ships with lower design speeds provide possibilities for using auxiliary wind propulsion devices to further reduce energy consumption. The kite is one type of auxiliary wind propulsion device that can be used for this purpose. The aim of this study is to investigate the influence of auxiliary kite propulsion on the performance of a panamax tanker, specifically on engine power reduction, course-keeping ability in different headings and on pitch and roll motion of the ship. The study is carried out by computer based simulations. Scenario combinations are established for various ship speeds, headings and weather conditions. For the purpose of simulation, a simplified auxiliary kite propulsion model is built and verified against full scale data. The SSPA in-house time domain maneuvering and seakeeping software – SEAMAN II is used for the study. The kite model is created as a subroutine to the SEAMAN software. The kite flies on the spherical surface along a predefined track. It performs span-wise rotation to achieve an optimum angle of attack. A NACA 4415 wing profile is adopted as the cross section of the kite. Aerodynamic forces are calculated based on the effective relative wind velocity and the optimum angle of attack. The radial component of the aerodynamic forces provides a traction force in the connection line. The traction force contributes to forces and moments acting on the simulated tanker. The numerical kite model was verified against full scale data. The deviations of traction force and thrust force between simulation and full scale could be controlled within 7%. Throughout the simulations, forces, moments, and motions of the tanker are recorded, as well as rudder angle and propeller efficiency. These output variables are plotted and analyzed to describe the influence of the auxiliary kite propulsion to ship performance. The result shows that auxiliary kite propulsion plays a significant role in reducing engine power in beam and following sea conditions. According to the SEAMAN simulations, a reduction of at least 40% could be obtained in many cases. The course keeping ability of the simulated panamax tanker is not affected by using the kite. The present study is a first step towards a fully dynamic kite model, where a control mechanism will be introduced to find the most favorable flying trajectory.
|
|
