SOLAS협약에서 2016.1.1.이후 건조되는 개방갑판 상부에 컨테이너를 5단 이상으로 적재하는 선박은 개방갑판구역(Weather Deck) 화재를 진압하기 위하여 Mobile Water Monitor를 의무적으로 비치하도록 하였다. 본 연구에서는 Mobile Water Monitor 실험장치 제작에 앞서 SOLAS협약의 설계기준을 만족하는 모델을 설계하기 위하여 노즐 오리피스 및 정류격자 길이 계산을 위한 유동해석을 실시하였고, 설계 모델의 구조안정성 평가를 위하여 유동-구조 연성해석을 실시하였다. 그 결과, 노즐 오리피스는 입구압력 4bar~9bar에서 각 29mm, 27mm, 25mm, 24mm, 23mm, 22mm로 계산되었고, 35° 분사 시 정류격자 길이 4cm일 때 분사거리 47m, 90° 분사 시에도 정류격자 길이가 4cm일 때 26m로 가장 길었다. 또한, 유동-구조 연성해석을 통해 최대변형이 2.47mm, 최대응력은 154.7MPa로 허용응력인 205MPa보다 낮아 구조적으로 안전한 것으로 확인되었다. 해석결과를 기반으로 실험장치를 제작하여 성능시험을 실시하였다. 그 결과, 입구압력 4bar, 분사각도 33.8°에서 분사거리 41m가 측정되었다. 해석결과와 차이가 있었으나, 분사각도와 외부 유동장에서 바람 등의 영향을 고려하였을 때 오차범위 내로 판단된다.
According to the SOLAS Convention, for vessels carrying more than five stages of containers on top of weather decks and constructed after 2016.1.1, a Mobile Water Monitor should be compulsorily provided to suppress weather deck fires. In this study, to design a model satisfying the design criteria of the SOLAS Convention prior to the production of the Mobile Water Monitor proto-type, flow analysis was performed to calculate nozzle orifice and stabilizer length, and flow–structure coupled analysis was performed to evaluate the structural stability of the design model. The nozzle orifice was thus calculated to be 29 mm, 27 mm, 25 mm, 24 mm, 23 mm, and 22 mm at 4 bar, 5 bar, 6 bar, 7 bar, 8 bar, and 9 bar, respectively; when the discharge angle was 35° and 90° and the stabilizer length was 4 cm, it was the longest at a distance of 47 m and 26 m. From the flow–structure coupled analysis, the maximum deformation was found to be 2.47 mm and the maximum stress to be 154.7 MPa, which was lower than the allowable stress, 205 MPa. An experimental apparatus was fabricated according to the analysis results, and tested for performance. Thus, a discharging distance of 41 m was measured at 4 bar and an injection angle of 33.8°. This result is different from the analysis result, but it was judged to be within the error range when considering the influence of wind on the injection angle and the external flow field.
C. H. Kang, Improving Storage Facilities for Dangerous Container Cargo in Busan Port, M.S. Thesis, Department of Shipping and Port Logistics, Korea Maritime and Ocean University, Korea, 2016.
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KOREA P&I CLUB, Safe Transport of Dangerous Cargo through Containers (Circular Number: 17/02-02), http://www.kpiclub.or.kr/board/bbs, Accessed February 8, 2017.
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IMO, SOLAS, Consolidated Edition, Translated and compiled by Korea Register, 2016.