Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Research on Energy Saving and Drag Reduction of Inland Vessel Based on Trim Optimization
Zhuoying Lu1, Jianglong Sun1,2,3*

1.School of Naval Architecture and Ocean Engineering (HUST), Wuhan, Hubei, China
2.Hubei Provincial Engineering Research Center of Data Techniques and Supporting Software for Ships (DTSSS), Wuhan, Hubei, China
3.Collaboration Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai, China

ABSTRACTobject, based on historical data, Li (2021) calculated the CO2 emissions
and voyage benefits of the ship at different speeds. The calculation
results show that the ship operates at a speed of 10 knots to 11 knots,
which can maintain a relatively high speed and profitable status, butalso to achieve a lower level of CO2 emissions from ships. However,this method of finding the best balance point of ship’s speed and fuelconsumption related calculation formula is not suitable for all ships.
During the LNG ship’s transportation, the cargo tank is dynamicallygenerating boil-off gas at all times, so it must be precisely controlled(Song, 2021). Improving the recommended efficiency of ships refers to
installing energy-saving devices such as fairing fins and rudder balls at
the stern of the ship to make the propeller flow evenly. Nevertheless,the energy-saving effect varies with different ship types and energysaving devices. In general, the energy-saving efficiency can reach 2%to 8% (Zhang, Zhao and Wang, 2016). Luo (2021) investigated theeffect of the heat exchanger water flow rate on the exhaust gas waste
heat utilization rate and the heat exchanger exhaust gas outlet
temperature. The results show that, the maximum hear recovery is
112.73kW, and the average waste heat recovery rate can reach 67.65%.
Although the water flow control of the exhaust heat recovery system
has strong practical value, this system is only suitable for ships
powered by diesel. At present, many ships have begun to use gas/oil
dual-fuel propulsion systems and more energy-saving sources, so thepractical application range of this method is not extensive.

In order to study the variation law of the resistance of the trim dragreduction to the fat and shallow draft type such as inland vessel, thispaper takes a 2000t bulk carrier as the research ship. The optimization
effect of trim adjustment on this type of ship is verified by the methodof combining model test and numerical calculation. The drag reduction
efficiency of the ship at the ballast and design draft is displayed
through the resistance change curve, pressure distribution diagram andwave height diagram, and the optimal trim curve at a certain speed isobtained.

KEY WORDS: trim optimization; Inland vessel; drag reduction;energy saving; CFDINTRODUCTION
Energy conservation and emission reduction of ships has become acommon issue around the world. According to the latest meeting
requirements of the Marine Environmental Protection Committee of theInternational Maritime Organization, from 2023, stricter technical andoperational monitoring of greenhouse gas emissions from ships oninternational voyages will be carried out. In recent years, with theimplementation of IMO's "2020 Sulfur Restriction Order", in order tomeet the requirements, most shipping companies choose to let theirships use higher-priced low-sulfur fuel oil, which increases operating
costs (Ai and Zhu, 2022).

Trim optimization is one of the easiest and cheapest methods among
many fuel-saving measures recommended by IMO as it does not
require any hull shape modification or engine upgrade (IMO, 2012).
For each draft and speed, there is a resistance optimum trim (Lv, Wu,Sun and Tu, 2013). In recent years, scholars have begun to study theenergy-saving effect of trim optimization. Coraddu, Oneto and Baldi(2017) established a model method for ship fuel consumption
prediction based on the data collected by onboard sensors in previous
years, and guided the ship to adjust the trim in real time in actual sea
conditions to achieve drag reduction. Yang, Zhu and Ai (2021) used
CFD method and data analysis method, took the standard ship model
KRISO Container Ship (KCS) as the object, studied the trim
optimization, and proposed the optimal trim angle at the economic
speed of the container ship. Xu (2020) proposed an energy-saving
control system of ship navigation based on trim optimization for theWhen it comes to green shipping, one of the main concerns about shiphydrodynamics is resistance reduction (Lyu, Tu, Xie and Song, 2018).
From a practical point of view, ship energy conservation and emission
reduction is to improve the energy utilization and transportation
efficiency of ships; reduce energy consumption, and use less energy
consumption to achieve efficient transportation of ships (Lv, 2020). At
present, the application of energy-saving and emission-reduction
technology mainly includes four aspects: the use of economical speed,
the reduction of drag and consumption by the hull, the improvement of
the propulsion efficiency of ships, and the recovery of waste heat andwaste gas of ships. Taking a single voyage of a ship as the research*Correspondence: sundapao@hust.edu.cn; Tel.: +86-136-6726-1800

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