An Analytic Solution to Sloshing Natural Periods for a Prismatic Liquid Cargo Tank with Baffles

J. Ocean Eng. Technol. 2005;19(6):16-21.

Shin, Jang-Ryong;Choi, Kyung-Sik;Kang, Sin-Young;

Offshore and Special Ship Hull Design Team, Daewoo Shipbuilding and Marine Engineering Co. Ltd.;Division of Ocean Development Engineering, Korea Maritime University;Division of Ocean Development Engineering, Korea Maritime University;

내부재가 설치된 직육면체 화물창 내의 Sloshing 고유주기 산정

신장룡;최경식;강신영;

대우조선해양(주) 해양특수선선체설계팀;한국해양대학교 해양개발공학부;한국해양대학교 해양개발공학부;

Keywords: Sloshing Natural Periods, Prismatic Tank with Baffles, Effective Fill-Depth Concept, Analytic Solution, Lloyd's Register Regulations

핵심용어: 슬로싱 고유주기, 내부재가 설치된 직육면체 화물창, 유효적재깊이 개념, 해석해, 로이드선급규정

Abstract

In the design of super tankers or LNG carriers, which transport a large amount of liquid in the cargo tanks, the structural d11mage due to liquid sloshing is an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a ship. In this study, the sloshing natural periods of a baffled tank, often installed to reduce liquid motion, is analyzed. A variational method is adopted to estimate the sloshing natural periods for a prismatic cargo tank with baffles of arbitrary filling depth of liquid; the results are compared with Lloyd's Register regulations on sloshing periods. In this study, using an effective liquid-fill-depth concept, sloshing periods for a baffled tank can be expressed by the same form as rectangular prismatic tanks without baffles. In contrast to Lloyd's Register regulations, which can be applicable only to cargo tanks with constant baffle size and distribution, the present results can be applicable to cases of variable baffle size and distribution.