Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ?

R. Folsø, Ulrik Dam Nielsen, F. Torti

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

Implementation of passive and active ride control systems into both linear frequency and non-linear time domain strip theories is described. The ride control systems considered can consist of T-foils, fins or a combination of these. These appendages are taken into account by considering the lift forces induced by the flow around them. In the frequency domain the appendages are included simply by modifying the equations of motion. This is done without introducing any non-linearities and hence the application of linear statistics is still valid. In the time domain the appendages are included by adding the lift forces to the exciting forces in the equations of motion. One of the advantages in the time domain is that the angle of attack can be limited easily, as is often the case in real full scale ride control systems. This way cavitation and finally stalling can be avoided. In the frequency domain limits on the angle of attack cannot be set. Since the lift coefficient is treated linearly the calculated lift force is severely overestimated in rough sea. Secondly the effect of including ride control systems in the calculations is demonstrated through comparisons of RMS values and of response operators for the ships main responses, e.g. motions, accelerations and sectional forces. Especially emphasis is given to the effect on the sectional forces, as preliminary results indicate that these in some cases are increased considerable by the T-foil ride control systems. Finally, the effect of the ride control systems on the hydro-elastic behaviour of the hull girder is investigated with the non-linear time domain strip theory code.
Original languageEnglish
Title of host publicationProceedings of 7th International Conference on FAST
Volume3, Session E
Place of PublicationNaples, Italy
PublisherDepartment of Naval Architecture and Marine Engineering and Institute of Navigation
Publication date2003
Pages33-40
Publication statusPublished - 2003
Event7th International Conference on Fast Sea Transportation (FAST 2003) - Ischia, Italy
Duration: 7 Oct 200310 Oct 2003
Conference number: 7

Conference

Conference7th International Conference on Fast Sea Transportation (FAST 2003)
Number7
CountryItaly
CityIschia
Period07/10/200310/10/2003

Cite this

Folsø, R., Nielsen, U. D., & Torti, F. (2003). Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ? In Proceedings of 7th International Conference on FAST (Vol. 3, Session E, pp. 33-40). Naples, Italy: Department of Naval Architecture and Marine Engineering and Institute of Navigation.
Folsø, R. ; Nielsen, Ulrik Dam ; Torti, F. / Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ?. Proceedings of 7th International Conference on FAST. Vol. 3, Session E Naples, Italy : Department of Naval Architecture and Marine Engineering and Institute of Navigation, 2003. pp. 33-40
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abstract = "Implementation of passive and active ride control systems into both linear frequency and non-linear time domain strip theories is described. The ride control systems considered can consist of T-foils, fins or a combination of these. These appendages are taken into account by considering the lift forces induced by the flow around them. In the frequency domain the appendages are included simply by modifying the equations of motion. This is done without introducing any non-linearities and hence the application of linear statistics is still valid. In the time domain the appendages are included by adding the lift forces to the exciting forces in the equations of motion. One of the advantages in the time domain is that the angle of attack can be limited easily, as is often the case in real full scale ride control systems. This way cavitation and finally stalling can be avoided. In the frequency domain limits on the angle of attack cannot be set. Since the lift coefficient is treated linearly the calculated lift force is severely overestimated in rough sea. Secondly the effect of including ride control systems in the calculations is demonstrated through comparisons of RMS values and of response operators for the ships main responses, e.g. motions, accelerations and sectional forces. Especially emphasis is given to the effect on the sectional forces, as preliminary results indicate that these in some cases are increased considerable by the T-foil ride control systems. Finally, the effect of the ride control systems on the hydro-elastic behaviour of the hull girder is investigated with the non-linear time domain strip theory code.",
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Folsø, R, Nielsen, UD & Torti, F 2003, Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ? in Proceedings of 7th International Conference on FAST. vol. 3, Session E, Department of Naval Architecture and Marine Engineering and Institute of Navigation, Naples, Italy, pp. 33-40, 7th International Conference on Fast Sea Transportation (FAST 2003), Ischia, Italy, 07/10/2003.

Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ? / Folsø, R.; Nielsen, Ulrik Dam; Torti, F.

Proceedings of 7th International Conference on FAST. Vol. 3, Session E Naples, Italy : Department of Naval Architecture and Marine Engineering and Institute of Navigation, 2003. p. 33-40.

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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N2 - Implementation of passive and active ride control systems into both linear frequency and non-linear time domain strip theories is described. The ride control systems considered can consist of T-foils, fins or a combination of these. These appendages are taken into account by considering the lift forces induced by the flow around them. In the frequency domain the appendages are included simply by modifying the equations of motion. This is done without introducing any non-linearities and hence the application of linear statistics is still valid. In the time domain the appendages are included by adding the lift forces to the exciting forces in the equations of motion. One of the advantages in the time domain is that the angle of attack can be limited easily, as is often the case in real full scale ride control systems. This way cavitation and finally stalling can be avoided. In the frequency domain limits on the angle of attack cannot be set. Since the lift coefficient is treated linearly the calculated lift force is severely overestimated in rough sea. Secondly the effect of including ride control systems in the calculations is demonstrated through comparisons of RMS values and of response operators for the ships main responses, e.g. motions, accelerations and sectional forces. Especially emphasis is given to the effect on the sectional forces, as preliminary results indicate that these in some cases are increased considerable by the T-foil ride control systems. Finally, the effect of the ride control systems on the hydro-elastic behaviour of the hull girder is investigated with the non-linear time domain strip theory code.

AB - Implementation of passive and active ride control systems into both linear frequency and non-linear time domain strip theories is described. The ride control systems considered can consist of T-foils, fins or a combination of these. These appendages are taken into account by considering the lift forces induced by the flow around them. In the frequency domain the appendages are included simply by modifying the equations of motion. This is done without introducing any non-linearities and hence the application of linear statistics is still valid. In the time domain the appendages are included by adding the lift forces to the exciting forces in the equations of motion. One of the advantages in the time domain is that the angle of attack can be limited easily, as is often the case in real full scale ride control systems. This way cavitation and finally stalling can be avoided. In the frequency domain limits on the angle of attack cannot be set. Since the lift coefficient is treated linearly the calculated lift force is severely overestimated in rough sea. Secondly the effect of including ride control systems in the calculations is demonstrated through comparisons of RMS values and of response operators for the ships main responses, e.g. motions, accelerations and sectional forces. Especially emphasis is given to the effect on the sectional forces, as preliminary results indicate that these in some cases are increased considerable by the T-foil ride control systems. Finally, the effect of the ride control systems on the hydro-elastic behaviour of the hull girder is investigated with the non-linear time domain strip theory code.

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VL - 3, Session E

SP - 33

EP - 40

BT - Proceedings of 7th International Conference on FAST

PB - Department of Naval Architecture and Marine Engineering and Institute of Navigation

CY - Naples, Italy

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Folsø R, Nielsen UD, Torti F. Ride Control Systems - Reduced Motions on the Cost of Increased Sectional Forces ? In Proceedings of 7th International Conference on FAST. Vol. 3, Session E. Naples, Italy: Department of Naval Architecture and Marine Engineering and Institute of Navigation. 2003. p. 33-40