Numerical Research on Global Ice Loads of Maneuvering Captive Motion in Level Ice

In level ice, the maneuvering motion of icebreakers has a major influence on the global ice loads of the hull. This study researched the influences of the drift angle and turning radius on the ice loads of the icebreaker Xue Long through a partial numerical method based on the linear superposition theory of ice loads. First, with reference to the Araon model tests performed by the Korea Research Institute of Ships and Ocean Engineering (KRISO), numerical simulations of Araon’s direct motion were carried out at different speeds, and the average deviation between numerical results and model test results was about 13.8%. Meanwhile, the icebreaking process and modes were analyzed and discussed, compared with a model test and a full-scale ship trial. Next, the maneuvering captive motions of oblique and constant radius were simulated to study the characteristics of ice loads under different drift angles and turning radii. Compared with the maneuvering motion model tests in the ice tank of Tianjin University and the Institute for Ocean Technology of the National Research Council of Canada (NRC/IOT), the numerical results had good agreement with the model test results in terms of the variation trend of ice loads and ice–hull interaction, and the influences of drift angle and turning radius on ice resistance and transverse force, which have a certain reference value for sailing performance research and the design of the hull form of icebreaker ships, are discussed.

Noise analysis in a model experiment for measuring ice loads using ice free water run

Модельный эксперимент в ледовом бассейне позволяет выяснить ледовые качества проектируемого ледостойкого морского сооружения, в том числе – получить представление о возможных ледовых нагрузках путем измерений глобальных нагрузок многокомпонентным динамометром. Чувствительность применяемого оборудования приводит к появлению шумовых помех в измеренном сигнале, вызванных действиями людей, обслуживающих эксперимент, работой машин и механизмов, гидродинамическими эффектами, а также явлениями в электросети. Отделение шумовых помех от полезного сигнала на этапе обработки данных является важной задачей, успешное решение которой позволит повысить достоверность результатов испытаний в ледовом бассейне. В настоящей работе изложен подход к очистке от шума результатов измерений многокомпонентного динамометра, применяемого в ледовом бассейне Крыловского государственного научного центра (Санкт-Петербург), с использованием амплитудно-частотного анализа участков пробега модели по чистой воде в пределах технологического окна во льду. Предложенный метод показал свою эффективность, в особенности – для экспериментов с моделью больших размеров. A model experiment in an ice tank allows to examine ice qualities of a designed ice-resistant marine structure, namely possible ice loads by measuring global loads with a multicomponent dynamometer. The sensitivity of the equipment leads to the noise interference in the measured signal caused by people's actions carrying out the experiment, by the operation of machines and mechanisms, hydrodynamic effects, as well as the phenomenae in the electrical power grid. It is important to separate noise interference from the relevant signal at the data processing stage, which will increase the reliability of ice tank experiments. This paper describes a method for denoising measurement results of a multicomponent dynamometer used in the ice tank of the Krylov State Scientific Center (St. Petersburg); the approach implies an amplitude-frequency analysis of model run areas in ice-free water within the technological window in the ice. The proposed method has demonstrated its effectiveness, especially for experiments with large models.