Abstract
In this study, the self-propulsion performance of a ship model with double-L-type podded propulsors was predicted. Additionally, a conversion method for the performance of a full-scale ship was established based on the correction method published by the International Towing Tank Conference (ITTC) for the scaling effect of a single podded propeller and research reports on pod tests conducted by different ship research institutes. The thrust deduction and wake fraction of the ship were also analyzed. Furthermore, the self-propulsion performance of a full-scale ship with double L-type pods was determined, the full- and model-scale ships compared in terms of their flow fields and pressure charts, and the influence of the scaling effect analyzed. In addition, the calculation results were compared with the conversion results of a full-scale ship, and the reliability of the method adopted for the performance estimation of a full-scale ship with double podded propulsors was verified. The findings reported herein can provide statistics and technical support for the design of L-type podded propulsors and their application in full-scale ships, which are of theoretical significance and practical value in the engineering domain.
Highlights
Open water and resistance tests are conducted on propellers to obtain the respective performances of the hull and the propeller, whereas self-propulsion tests are used to analyze the influence of various efficiency parameters and stern wake flow on propeller efficiency and the impact of the propeller on ship resistance; the information obtained from these tests can provide references for propeller design
The flow and resistance of the hull were calculated via three methods, which can be differentiated by the treatments concerning the free surface: The first method determined only the single-phase flow of water; the second involved investigating the two-phase flow of water and gas; and the third simplified the propeller by using the body force model, making the free surface treatment more convenient and increasing the amount of obtained information concerning the flow around the hull
The results suggested that the method was valuable for predicting the hull resistance; it could not ensure calculation accuracy for the thrust deductions and wake flow fractions
Summary
Open water and resistance tests are conducted on propellers to obtain the respective performances of the hull and the propeller, whereas self-propulsion tests are used to analyze the influence of various efficiency parameters and stern wake flow on propeller efficiency and the impact of the propeller on ship resistance; the information obtained from these tests can provide references for propeller design. To estimate the self-propulsion performance of a ship with a podded propulsor, it is necessary to accurately predict the hydrodynamic interactions among the pod, propeller, and hull. In terms of experimental research, Maritime Reesarch Institute Netherlands (MARIN), Hamburgische Schiffbau-Versuchsanstalt GmbH (HSVA), and other scholars have conducted a large number of tests on the hydrodynamic performance of podded propulsors In their research, they suggested that research methods concerning the tests and measurement of the mutual interference between the pod and the hull should be adapted for different types of podded propulsors (pushing or pulling). The self-propulsion performance of a full-scale ship with double L-type pods was estimated, the flow fields and pressure charts of the full scale and model scale ships compared, and the influence of the scaling effect investigated. The calculation results were compared with the conversion results of a full-scale ship, and the reliability of the method adopted for estimating the performance of a full-scale ship with double podded propulsors verified
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