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Shape and Spacing Effects on Curvy Twin Sail for Autonomous Sailing Drone
Minh-Ngoc Pham,김부기,양창조 해양환경안전학회 2020 해양환경안전학회지 Vol.26 No.7
There is a growing interest this paper for ocean sensing where autonomous vehicles can play an essential role in assisting engineers, researchers, and scientists with environmental monitoring and collecting oceanographic data. This study was conducted to develop a rigid sail for the autonomous sailing drone. Our study aims to numerically analyze the aerodynamic characteristics of curvy twin sail and compare it with wing sail. Because racing regulations limit the sail shape, only the two-dimensional geometry (2D) was open for an optimization. Therefore, the first objective was to identify the aerodynamic performance of such curvy twin sails. The secondary objective was to estimate the effect of the sail’s spacing and shapes. A viscous Navier-Stokes flow solver was used for the numerical aerodynamic analysis. The 2D aerodynamic investigation is a preliminary evaluation. The results indicated that the curvy twin sail designs have improved lift, drag, and driving force coefficient compared to the wing sails. The spacing between the port and starboard sails of curvy twin sail was an important parameter. The spacing is 0.035L, 0.07L, and 0.14L shows the lift coefficient reduction because of dramatically stall effect, while flow separation is improved with spacing is 0.21L, 0.28L, and 0.35L. Significantly, the spacing 0.28L shows the maximum high pressure at the lower area and the small low pressure area at leading edges. Therefore, the highest lift was generated.
류인호,김부기,양창조 해양환경안전학회 2021 해양환경안전학회지 Vol.27 No.7
우리나라는 해상활동의 중요성이 크며, 산업화에 따른 이상기후 현상 등을 규명하기 위해 육상에 많은 자동기상 관측설비 를 운영 중이지만 해상에서는 그 수가 매우 부족하다. 또한, 해양안전정보 구축 등을 위해 해양조사선을 운영 중이나 접근이 어려운 곳이 많고 높은 운영비용이 요구된다. 따라서 다양한 해양관측 등이 가능한 소형무인화선박의 개발이 필요하다. 한편 소형 무인화 선 박에서 세일(Sail)은 항해 성능에 큰 영향을 미치므로 이에 대한 많은 연구가 진행되고 있다. 본 연구에서는 기존 에어포일 형상보다 높은 공기역학적 성능을 갖는 것으로 알려진 트윈커브세일(Twin curvy sail)의 설계변수인 캠버(Camber)효과에 대해 검토하였다. 5 종류 의 캠버에 대해 유동해석 결과, 캠버 크기가 9 %일 때 가장 높은 양력계수를 나타내었다. 트윈커브세일의 경우 Port sail과 Starboard sail 의 상호작용에 의해 받음각 23°에서 가장 높은 양력계수를 갖고, Port sail의 경우 받음각 20°에서 가장 높은 양력계수를 Starboard sail의 경우 받음각 15°에서 가장 낮은 양력계수를 나타내었다. 또한, 트윈커브세일은 모든 받음각에서 에어포일 형상인 NACA 0018보다 높은 양력계수를 나타내었다. In Korea, the importance of marine activities is great, and automatic weather observation facilities are operating on land to investigate abnormal weather phenomena caused by industrialization; however, the number of facilities at sea is insufficient. Marine survey ships are operated to establish marine safety information, but there are many places where marine survey ships are difficult to access and operating costs are high. Therefore, a small, unmanned vessel capable of marine surveys must be developed. The sail has a significant impact on the sailing performance, so much research has been conducted. In this study, the camber effect, which is a design variable of the twin curvy sail known to have higher aerodynamic performance than existing airfoil shapes, was investigated. Flow analysis results for five cases with different camber sizes show that the lift coefficient is highest when the camber size is 9%. Curvy twin sails had the highest lift coefficient at an angle of attack of 23° because of the interaction of the port and starboard sails. The port sail had the highest lift coefficient at an angle of attack of 20°, and the starboard sail had the lowest lift coefficient at an angle of attack of 15°. In addition, the curvy twin sail had a higher lift coefficient than NACA 0018 at all angles of attack.
류인호,양창조,한원희 해양환경안전학회 2022 해양환경안전학회지 Vol.28 No.5
Recently, marine surveys using unmanned ships are attracting attention, and research on small unmanned ships using sails is on the rise. Sail drones can be used for marine surveys, monitoring, and pollution management. Therefore, in this study, using the method of estimating the ship speed for twin sail drones, the optimal conditions for sailing are checked, and the performance to be considered in the initial design stage, such as the motion performance and resistance of the sail drone. Consequently, the twin sail drone had a speed lower than 2.0m/s, and the stability satisfied the rule by DNV. In addition, the maximum speed at an angle of attack of 20° at TWA 100° was 1.69 m/s and that at an angle of attack of 25° at TWA 100° was 1.74m/s. 최근 무인선을 활용한 해양 조사가 주목을 받고 있으며, 특히 세일을 이용한 소형 무인 드론에 대한 연구가 고조되고 있다. 세일 드론의 용도는 해양 조사, 감시 및 오염방제 등을 들 수 있다. 따라서 본 연구에서는 트윈 세일을 채용한 드론에 대해 선속을 추정하는 방식을 이용하여 항주최적조건을 확인하고 세일드론의 운동성능 및 저항 등 초기설계단계에서 검토해야 할 성능에 대해서 고찰하고자 하였다. 그 결과, 트윈 세일 드론은 항해속도를 2.0m/s 이하로 유지하는 편이 유리하며 복원성 또한 DNV에서 규정하는 조건을 충족시켰다. 또한, TWA 100°일 때 받음각 20°에서 최고속력은 1.69m/s, TWA 100°일 때 받음각 25°에서 최고속력은 1.74m/s를 보였다.
Mechanism Development and Heading Control of Catamaran-type Sail Drone
Dong-Woo Man,Hyun-Sik Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.5
The need for energy harvesting in marine environments is gradually increasing owing to the energy limitation of marine robots. To address this problem, a catamaran-type sail drone (CSD), which can harvest marine energies such as wind and solar, was proposed in a previous study. However, it was designed and manufactured without considering the stability, optimal hull-form, and maintenance. To resolve these problems, a CSD with two keels, a performance estimator, V-shape hulls, and modularized components is proposed and its mechanism is developed in this study. To verify the performance of the CSD, the performance estimation using smoothed-particle hydrodynamics (SPH) and the heading control using fuzzy logic controller (FLC) are performed. Simulation results show the attitude stability of the CSD and the experimental results show the straight path of the CSD according to wind conditions. Therefore, the CSD has potential applications as an energy harvesting system.