Investigation of inland ship resistance, propulsion and manoeuvring using literature study and potential flow calculations

Manoeuvring simulations can be of good use in determining whether an inland ship may be allowed access to a certain channel/river or not. The SURSIM mathematical model is able to predict the necessary manoeuvres and can therefore be used to determine the acceptance of ships on fairways. However, the SURSIM program is mostly developed for use with sea-going ships, and therefore effort is put in investigating how the SURSIM model should be adjusted to be useful for inland ship manoeuvring simulations. This report particularly focuses on the shallow water corrections for resistance, propulsion and manoeuvring forces. It is chosen to carry out a literature study into inland ship resistance and propulsion, while for manoeuvring potential flow calculations using DelKelv are carried out. The performance of DelKelv calculations in the field of ship manoeuvring is tested using a validation study, and afterwards shallow water corrections for an inland ship are computed using potential flow theory.Ship HydromechanicsMarine & Transport TechnologyMechanical, Maritime and Materials Engineerin

Influence of inland vessel stern shape aspects on propulsive performance: Derivation of insights and guidelines based on a computational study

This research focuses on identifying the most important stern shape aspects, with regard to resistance and propulsion power, of inland ships. Such information should help designers to determine which hull form aspect to adjust in case design requirements need them to do so. The information is obtained by firstly conducting a large series of CFD calculations, using the PARNASSOS code, for systematically varied inland ships. Next, response surface technologies are used to identify the most important aspects. This is done by sequentially adding and/or removing parameters from the response surface in order to find the combination of parameters that explains the majority of the variance in the performance data for the tested hull forms. Finally, an optimization algorithm is used to determine the optimal hull forms for varying displacement, showing which parameters should be adjusted preferably in order to increase (or decrease) ship displacement. This, specifically, should aid designers in making the trade-off between displacement (or cargo capacity) and energy consumption.Ship Design, Production and Operation

The influence of shallow water and hull form variations on inland ship resistance

Effects of a hull form variation and shallow water on a 110-meter inland ship are presented as preliminary results of the Top Ships project, which is initiated in order to improve inland ship design tools and design guidelines.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin

A proposal for standard manoeuvres and parameters for the evaluation of inland ship manoeuvrability

Inland ship manoeuvrability has more complex features than that of sea-going ships due to constrains of inland waterways and complicated ship configurations. In order to clarify the complexity of manoeuvring, impact factors of navigation environment and ship particulars are first analysed to point out the determinants for evaluation. After reviewing existing standards of testing manoeuvres and criteria, it is concluded that there is a lack of knowledge to develop design guidance for manoeuvring in shallow/restricted water, which is the common sailing condition for inland vessels, making a proper evaluation more difficult. For the purpose of achieving more realistic judgement on manoeuvrability, benchmark manoeuvres are proposed for discussion. Conclusions are drawn on the need of validation for the effectiveness of testing manoeuvres and elaborate manoeuvring criteria for inland vessels.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin

Design guidelines and empirical evaluation tools for inland ships

For inland ships, state-of-the-art hull form design is to a large extent based on experience, common sense, or adjusting previous designs. The idea therefore arises that further optimization is possible if the right knowledge is available. This knowledge is insufficiently available due to two main reasons. First, research into inland ship optimization is usually omitted from the design process due to the high cost compared to the design budget. This has led to a lack of fundamental knowledge about the complex hydrodynamics around the hull of an inland ship. Second, as a consequence of omitting optimization research, adequate empirical power prediction methods have not been developed for inland ships due to the lack of data. In the Top Ships project, effort is put in the development of an empirical method for inland ship power estimation as well as the derivation of design guidelines. Both should aid designers in the process of a new ship's design. The present paper gives an overview of available information from literature that aids to design of inland ships. Design guidelines and power prediction methods that relate to the design of a new inland ship are presented and discussed. The conclusions emerging from this review lead to the choice of focus in the Top Ships project. Therefore an introduction, the approach and intended results of this project are briefly presented as well.Marine and Transport TechnologyMechanical, Maritime and Materials Engineerin

Hydrodynamic characteristics of multiple-rudder configurations

The manoeuvring performance of inland vessels is even more crucial than that of seagoing ships due to more complex navigation environment. One of the most effective possibilities to improve ship manoeuvrability is to change the rudder configuration. Twin or even quadruple rudders and high-lift profiles are widely applied to inland vessels. When inland vessels equip with multiple rudders, the interaction effects between the rudders affect the hydrodynamic characteristics of each rudder. This paper presents a study on these interaction effects using two-dimensional Reynolds-averaged Navier–Stokes (RANS) methods. Various twin-rudder and quadruple-rudder configurations with different profiles and spacing among the multiple rudders were studied. RANS simulations were performed with a k−ω SST turbulence model and a pressure-based coupled algorithm. Series of NACA, IFS and wedge-tail profiles were tested. Regression formulas have been proposed for the twin-rudder lift and drag coefficients. Finally, interaction effects on multiple rudder hydrodynamics have been summarised.Accepted Author ManuscriptShip Design, Production and OperationsMarine and Transport Technolog

A modification of the ITTC57 correlation line for shallow water

The ITTC57 correlation line, which is derived based on the assumption that the water in which ships advance is infinite deep and wide. However, for ships sailing in the waterway with limited water depth, the frictional resistance will be influenced leading to a decreasing accuracy of the prediction with this correlation line. In this study, a modification of the ITTC57 correlation line is proposed to correct the effects in very shallow water specifically for the flat area of the bottom of the ship. Under some assumptions, this area can be simplified to a 2D flat plate with a parallel wall close to it to study how the shallow water conditions of two interacting boundary conditions are affecting the flat plate friction coefficient. Computational fluid dynamics (CFD) calculations are applied to investigate how a friction line specifically in shallow water deviates from the conventional lines. Such deviations may severely affect the extrapolation of a ship model’s resistance to full scale and, therefore, the accuracy of ship’s performance prediction. Cases at ten Reynolds numbers from 105 to 109 are simulated on the 2D flat plate. Seven different distances between the flat plate and the parallel wall were chosen to generate various shallow water conditions, and consequently, a database including frictional resistance coefficients, Reynolds numbers and the distance between those two walls is built. Results indicate that thinner boundary layers are observed in shallow water conditions, and the scale effects which has a significant impact on resistance extrapolation are also observed. Furthermore, the assumption of the zero pressure gradients (ZPG) which is commonly used in deep water is no longer valid in extremely shallow ones. Finally, a modification for the ITTC57 correlations line considering shallow water effects is proposed, which is willing to improve the prediction of the frictional resistance of those ships with a large area of flat bottom and sail in shallow water.Ship Design, Production and OperationsShip Hydromechanics and Structure

Optimization of ships in shallow water with viscous flow computations and surrogate modeling

Shallow water effects change the flow around a ship significantly which can affect the optimum design of the hull. This paper describes a study into the optimization of the aft ship region for various water depths. The research focuses on variations of the following parameters of a hull form: The athwart ship’s propeller location, the tunnel top curvature, the flat-of-bottom shape in the stern region and the stern bilge radius. All hull form variants are valuated in 3 different water depths using a viscous flow solver, and a surrogate model is created for each water depth. Pareto plots are used to present the trade-off between the optimization for one or another water depth. Finally, specific hull forms are chosen and the differences in flow behavior among hull forms and water depths are explained.Ship Design, Production and Operation