CFD Analysis on the Interceptor Performance of Planing Boats in Calm Water and Waves

Abstract

Accurate prediction of the resistance and seakeeping performance is one of the most important aspects of the hull design parameter. Generally, the prediction of resistance of a planing hull form is more complicated than its displacement. Planing hull form has unique characteristics such as trim, heave, hard-chine, high-speed, deadrise angle, and a significant lifting force on the hull bottom, and the force acting on it is the most complex hydrodynamics calculation. Basically, it is a fundamental aspect of overall high-speed ship analysis evaluating resistance and seakeeping. The numerical analysis using the Finite Volume Method (FVM) was selected to solve the hydrodynamics problem using Star-CCM+ code developed by CD-adapco. In this study, Reynolds-Averaged Navier-Stokes equation simulation was used to describe the turbulence model with the k-ε. In general, the Volume of Fluid (VOF) modeling used the Eulerian multiphase flow which considers water and air as flow phases and uses variables such as size, shape, and density. The purpose of this study was to introduce planing boats numerical benchmark, showing the capability to predict resistance and seakeeping performance. The approach has been used in previous studies in calm water and wave condition. High-speed vessels validation studies were carried out using the historical benchmark experiments of Fridsma, VPS, VWS, VWC, and Aragon-2. The high-speed crafts have some weaknesses, including losing power in running trim, impact damage, heeling to the port or starboard, porpoising and combination motions. For this reason, it is necessary to control the motion performance in high-speed crafts. The most popular trim control devices are trim tab and interceptor controlling the vertical plates. Additionally, the study also discussed the parameter of the interceptor to improve seakeeping motions. The Computational Fluid Dynamics (CFD) simulation showed the interceptor x-300, x-450, and x-600 might be used to solve the high-speed crafts problems. The optimal interceptor reduces total resistance up to 18% in calm water condition. However, the most effective interceptor x-series for boat length of around 8 meters is interceptor x-300. In high-speed Froude number, the interceptor is not needed since it negatively influences the performance of the craft by producing a powerful movement, generating a negative trim. The running trims used in wave condition were selected after investigation of the calm water results. The interceptor x-300 reduce the total resistance and motions response in wave condition. The CFD results showed the interceptor mounted at Fr 0.87 was able to improve the motion performance. The results showed a decrease of pitch and heave motion up to of 21.3% and 17.1% respectively in regular wave condition. A planing boat with interceptor had an excellent motion–reduction effect.

활주형 선박의 저항 및 운동성능을 정확하게 수치적으로 계산하는 일은 매우 필요한 일이나 최근까지는 어려움이 있었다. 그러나 최근 개인용 계산기의 계산 성능이 개선되면서 어느 정도 설계에 적용 가능하게 되었다. 본 심사 논문은 CFD를 이용하여 활주형 선박의 저항 및 운동성능을 예측할 수 있음을 보여주고 있다. Star-CCM+을 이용하여 계산된 결과를 문헌에 나타난 실험 결과와 비교함으로써 그 유용성을 보여주고 있다. 많은 문헌에서 계산 결과와 비교에 사용되는 Fridsma 실험 결과와 최근 국내에서 수행, 발표된 VPS, VWS, VWC 선형에 대해 계산 결과를 비교하여 좋은 일치도를 보여주고 있다. 고속 활주형선에서 운동 제어 목적으로 자주 사용되는 인터셉터에 대해서도 수치 계산을 수행하여 실험 결과와 좋은 일치를 보이고 있다. 이를 이용하여 최적의 인터셉터를 찾는 과정을 보이고 있다. 뿐만 아니라 이를 확대하여 실험에서 수행하지 못했던 여러 가지 경우에 대해 추가 계산을 수행하여 그 성질을 밝히고 있다.