滑航艇姿態對操縱性與耐海性影響評估

THE EFFECT OF PLANING HULL ATTITUDE ON THE CHARACTERISTICS OF MANOEUVRING AND SEAKEEPING

本研究之重點在於將滑航艇航行中的姿態變化加入船舶的操縱性及耐海性研究中考量，並做為未來軍用高速滑航艇之設計參考。操縱性部分假設滑航艇之穩態動升角即為該船速之俯仰角，以此姿態進行平面運動機構實驗（planar motion mechanism），得到滑航艇不同滑航姿態的流體動力係數。將這些流體動力係數進行迴歸分析，導入船舶運動方程式，進行迴旋圈之電腦模擬。耐海性部分則使用二維截片理論在頻率領域建立不同穩態動升角下不同船速、吃水、波頻、波向的耐海流體動力係數資料庫。使用資料庫在時程領域進行四階Runge-Kutta數值方法計算，得到船體在波浪中時程領域的運動量。由本研究結果可以得知，無論是操縱性或是耐海性方面，考慮滑航姿態之船體運動都與原先的計算方式相差甚大。

The intention of this study is to estimate the manoeuvring and seakeeping motion of planing hull, with the consideration of planing hull attitude. The manoeuvring part assumes that the hydrodynamic coefficients varies as the planing hull attitude changes, which directly relates to ship speed changes. Thus, the PMM (Planar Motion Mechanism) test are performed to measure the hydrodynamic coefficients. Then the turning circle test is simulated by the 4th Runge-Kutta approach with the 4DOF ship motion equation. Based on the two-dimensional strip theory, the latter part establishes a seakeeping hydrodynamic coefficients database with a previously developed seakeeping motion program running in frequency domain. A variety of ship speeds, drafts, wave frequencies, wave directions are considered. Then, combining the foregoing attitude assumption and the database, ship motion are calculated by 4th Runge-Kutta approach. Based on the results of current work, planing hull performs different motion characteristics compared to displacement ship. The turning circle results considering planing attitude is smaller than that with even keel waterline. And the ship speed drops more with attitude change. The time-domain seakeeping motion results also shows that the calculation of frequency domain had an generally overestimating trend on planing hull. The ship motion in waves tends to be lower in the time-domain simulation. And the nondimensional ship motion is going to be lower if wave amplitude grows.