Coefficients of Propeller-hull Interaction in Propulsion System of Inland Waterway Vessels with Stern Tunnels

Propeller-hull interaction coefficients - the wake fraction and the thrust deduction factor - play significant role in design of propulsion system of a ship. In the case of inland waterway vessels the reliable method of predicting these coefficients in early design stage is missing. Based on the outcomes from model tests and from numerical computations the present authors show that it is difficult to determine uniquely the trends in change of wake fraction and thrust deduction factor resulting from the changes of hull form or operating conditions. Nowadays the resistance and propulsion model tests of inland waterway vessels are carried out rarely because of relatively high costs. On the other hand, the degree of development of computational methods enables’ to estimate the reliable values o interaction coefficients. The computations referred to in the present paper were carried out using the authors’ own software HPSDKS and the commercial software Ansys Fluent

Drag and Torque on Locked Screw Propeller

Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades). The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers

Hull Resistance of An Inland Waterway Vessel in Model Scale and in Full Scale

Data from model tests of an inland waterway vessel in shallow water have been used by the authors to prepare the resistance prediction in full scale. The common ITTC-1978 extrapolation procedure was applied using form factor determined according to the Prohaska method and, separately, by fitting the approximation function to resistance data. At the same time a series of CFD computations of ship flow has been carried out in model scale and in full scale, with double-body model as well as including the effect of free surface. The results of computations were used to determine total resistance and form factor. The values of form factor determined using different methods are similar and relatively high in comparison to values being applied to conventional sea going ships. Resistance prediction according to the ITTC-1978 with form factor was compared to prediction without form factor. The relative difference of resistance amounts 28% at ship speed of 10 km/h and 24% at ship speed of 12 km/h

CFD Based Hull Hydrodynamic Forces for Simulation of Ship Manoeuvres

There have been developed numerous mathematical models describing the motion of a ship. In opinion of present authors the CFD is mature enough to determine with confidence the hydrodynamic characteristics necessary to simulate ship manoeuvres. In this paper the authors present the attempt to determine the hull hydrodynamic forces using the results of CFD computations of ship flow. Results show qualitative agreement with reference data and reveal shortcomings due to simplifying assumptions applied in CFD computations

Analysis of hull resistance of pushed barges in shallow water

These authors performed a set of numerical calculations of water flow around pushed barges differing to each other by bow forms. The calculations were executed by means of FLUENT computer software. Turbulent free-surface flow of viscous liquid was considered. In this paper the calculated values of barge hull resistance split into bow, cylindrical and stern part components, have been compared and presented

The effect of limited depth and width of waterway on performance of ducted propellers

Model tests of propeller performance in bollard conditions, in deep and shallow water, were carried out at Ship Design and Research Centre in Gdansk. Corresponding calculations of propeller performance with account for finite dimensions of canal cross-section were carried out at Wroclaw University of Technology by using their own theoretical model of propeller -hull interaction. The calculations were carried out in model scale, at the same water depth as in model tests. For given hull form, propeller geometry and canal cross-section the HPSDK computer code was used to calculate wake fraction, as well as propeller thrust, torque and efficiency. The distribution of pressure on waterway bottom and ship sinkage were also determined