본 연구에서는 80k Bulk carrier의 저항성능 향상을 목적으로 선미부에 1개의 핀을 부착해 선미 유동을 제어하였고, 저항성능 및 반류의 변화를 분석하였다. 부착된 핀은 직사각형 단면을 가지며, 길이와 폭, 두께는 고정된 채 길이 및 흘수 방향 부착 위치와 유선에 대 한 각도만 변화가 있었다. 나선 및 핀이 부착된 선체에 대한 모형 스케일에서의 CFD 해석이 수행되었고, 그 결과를 실선 확장 후 비교하 였다. 핀은 프로펠러로 유입되는 빌지 볼텍스의 경로를 선미 트랜섬 쪽으로 변화시켰고, 이는 프로펠러 상부와 선미부의 압력을 증가시켰 다. 이로 인해 선체의 압력저항 및 전 저항이 감소되었으며, 감소율은 핀의 부착 위치가 선미 및 선저와 가까울수록 높았다. 또한 핀은 공 칭반류를 감소시켰는데 핀의 각도가 커질수록 반류의 변화가 컸고, 전 저항 저감률은 최대가 되는 특정 각도까지만 비례하였다. 대상 선 박에 단일 핀을 부착했을 시의 최대 전 저항 저감률은 약 2.1 %였고, 선미로부터 수선간장의 12.5%, 선저로부터 흘수의 10 % 위치에 14 의 각도로 부착됐을 때이다.

In this study, a high speed Rigid Inflatable Boat(RIB) with about 10 meters length is developed. Design speed of the boat is 30 knots (15.43 m/s) using 250 hp twin engines and main material is aluminum. Resistance performance related to the free running attitude as trim and sinkage are discussed and wave patterns are observed to make clear the relationship between the performance and wave characteristics using model test and CFD analysis. The results show that not only wave patterns but also free running attitude of the boat have a strong influence on resistance performance. CFD results including free surface give good relative tendency for effective power and the attitude comparing model test results. CFD analysis used in this study can be used at initial ship design stage of high speed boat.

In this study, a 30ft class high speed catamaran cruise boat is designed and resistance performances are investigated by model test at a circulating water tank. Design speed of the boat is 17knots(8.7m/s) and maximum speed is 20knots(10.3m/s) using 330ps twin engine. Each single bodies are designed unsymmetric planing hull considering high speed-length-ratio(Froude number) and wave interaction at inner part of the hull. Small size fins like chine are attached near free surface at each outside of the hull to separate wave along the hull side. The results show that the small chine plays a big role in separating the wave flowing along the hull. However, in the case of relatively heavy boat such as the developed hull, such a small power due to chine can not cause additional lift and cause resistance increase.

연·근해어선들은 운항 또는 조업시 안정성(복원성능 및 횡동요 저감 성능)을 향상시키기 위해 여러 가지 부가물을 설치하며, 일반적으로 Fig. 1과 같이 세 가지로 분류할 수 있다. Bare hull을 포함하여 각 부가물이 단독으로 부착된 경우 3가지, 복수의 조합으로 부착된 경우 3가지 그리고 3가지 모두 부착된 1가지에 대하여 수치 계산을 수행하였다. Table 1은 Bare hull에 대한 주요치수를 나타낸 것이고, Table 2는 3가지 부가물에 대한 주요치수를 기술하였다. 3가지 선체 부가물에 대하여 CFD에 의한 유체동역학적 성능을 평가하였다. 각각의 부가물에 대하여 단독, 2개씩 조합된 복수 그리고 3개 모두 부착된 경우에 대하여 평가를 하였다. 1번 부가물의 경우 압력저항이 마찰저항 보다 차지하는 비율이 큼을 알 수 있었다. 2번과 3번 부가물의 경우 압력저항과 마찰저항이 거의 대동소이 함을 알 수 있었다. 복수조합과 3가지 모두 부착된 경우 부가물 상호간의 상관관계는 매우 작음을 알 수 있었다. 11노트에서 2번 부가물과 모든 부가물이 부착된 경우 유효마력 관점에서 약 9 % 차이를 보였다.

The planing hull is characterized by a large change in the posture according to the speed, and the shape of the propeller varies, so that the hull resistance varies greatly depending on the propeller used. Especially, the Savitsky system, which is widely used for estimating the resistance of planing hull, does not consider the characteristics of these propeller and ship bottom spray rails. In this paper, in order to investigate the difference in resistance characteristics between the propeller and the bottom of the propeller of 6m and 12m class propeller using propeller such as outboard or stern drive, A comparative test was conducted on resistance and attitude posture changes in the Circulating Water Channel of Institute of Medium & Small Shipbuilding. As a result of comparison test, it was confirmed that there is a clear difference in the attitude change due to the presence of the bottom floor spray rail and the change in resistance characteristics due to the installation of the propeller. However, attitude change with the propeller was found to be insignificant.

In this study, electric propulsion leisure boat with 9 meters length is designed and the performances are investigated by CFD analysis and model test. Maximum speed of the developed boat is 15knots(7.7 m/s) using 80Kw electric motor. Catamanan type hull form with slender body is adopted considering high Froude number and large deck area. Two kinds of hull forms are designed and the performances are compared in resistance point of view. Wave patterns are observed to make clear the relationship between resistance performance and wave characteristics. The results show that not only wave interaction due to shoulder waves but also stern waves have a strong influence on resistance performance and CFD analysis including free surface can give useful informations at initial ship design stage for high Froude number catamaran boat.

In the present study, numerical analysis algorithm for the hull form optimization was taken into account using optimization algorithm. In this algorithm the sequential quadratic programming method was applied as an optimizer and the potential-based panel method was adopted to get the wave resistance coefficient as the objective function. The hull form was modified using the B-spline surface modeling technique during the whole optimization process. The developed numerical analysis algorithm was applied to a passenger ship and the optimized ship were compared with the original ship.

As a “kind of” mature ship form, planing hull has been widely used in military and civilian areas. Therefore, a reasonable design for planing hull becomes more and more important. For planing hull, resistance and trim are always the most important problems we are concerned with. It affects the planing hull’s economic efficiency and maneuverability very seriously. Instead of the expensive towing tank experiments, the development of computer comprehensive ability allows us to previously apply computational fluid dynamics(CFD)to the ship design. In this paper, the CFD method and Goal Driven Optimization (GDO) were used in the estimations of planing hull resistance and running attitude to provide a possible method for performance computation of planing hull.

In the present study, numerical analysis algorithm for the hull form optimization was taken into account using optimization algorithm. In this algorithm the sequential quadratic programming method was applied as an optimizer and the potential-based panel method was adopted to get the wave resistance coefficient as the objective function. The hull form was modified using the B-spline surface modeling technique during the whole optimization process. The developed numerical analysis algorithm was applied to the 300K VLCC and the optimized ship were compared with the original ship.

본 연구의 주목적은 쌍동선형의 조파저항성능을 평가할 수 있는 수치해석 프로그램을 개발하는 것이다. 개발된 프로그램을 이용하여 비대칭과 대칭인 단동선형을 가진 서로 다른 두 가지 쌍동선에 대하여 수치계산을 수행하여 저항성능을 평가 하였다. 타당성 검증을 위해서 수치해석 결과 중 선수와 선미에서의 침하량, 트림 그리고 조파저항 계수를 수조모형시험 결과와 비교하였다. 이러한 비대칭 그리고 대칭 선형이 가지는 쌍동선의 유체역학적 특성에 관한 비교분석 자료는 향후 선형개발 시 충분한 활용 가치가 있다고 판단된다.

This study develops an efficient numerical algorithm to predict wave-resistance performance of a catamaran hull. The developed numerical algorithm is applied to evaluate wave-resistance performance for two different twin hull forms with a asymmetric and a symmetric mono hull. Numerical calculations and model tests are compared to validate a developed numerical algorithm adopted in the current work. Comparisons are carried out through the sinkage at the bow and stern, the trim and the wave-making resistance coefficient. Model test is performed in order to verify the numerical results. The comparative analysis study regarding hydrodynamic characteristic of different twin hull forms is worthy of application in the catamaran hull form development stage.

A series of model tests carried out at the CWC of WJFEL for the purpose of prediction of resistance for the performance and improvement of resistance by attaching appendage for the ship of 50 knots class planing hull. The resistance performance evaluation has been carried out for the bare hull and for the appendage hull with two different depth of vertical type wedges. In the bare model test, trim and sinkage is calculated for the planing hull and the resistance is calculated. For minimizing the resistance, wedge appendage is attached and tested. Analysis and tests shows that for a 12.5mm wedge, resistance is minimum and overall power tallied to 5636ps.

This study was carried out at the CWC of Chosun university for the purpose of resistance performance improvement of planing hull, and the results of the tests were confirmed cooperatively with WJFEL. G/T 100 ton class planing hull form was selected, and the improvement of hull form including appendages were performed by using some model test techniques. The model test scope comprises resistance relative tests including wave profile observation, trim and sinkage measurement and flow visualization tests at full load and trial conditions for one bare hull and for two appended hulls. The final wedge and spray strip combined with improved hull form showed about 1.0 knot speed improvement at both of full and trial conditions, and outstanding improvement for fore wave phenomena.