Against the backdrop of the rapid development of the global shipping industry and the deep advancement of “dual carbon” goals, energy transition, energy conservation, and emission reduction have become core issues in marine transportation. As a critical component of clean and renewable energy, the efficient development and utilization of wind energy are pivotal for achieving low-carbon shipping. Exhaust turbine sails, an innovative application of active suction control in marine aerodynamic propulsion, regulate boundary layer flow through active suction to enhance wind energy utilization efficiency, which has emerging as a research hotspot in the green transformation of modern shipping. This paper aims to synthesize research on exhaust turbine sails. First, based on fundamental fluid mechanics principles, it analyzes the impact of boundary layer separation on the aerodynamic characteristics of structural bodies. Second, through case studies, it summarizes flow control effects under different suction parameters. It further introduces combined blowing and suction control strategies to explore their influence on boundary layer management. Finally, it details the research progress of exhaust turbine sails, explaining their core principle: active suction control delays or prevents boundary layer separation, effectively suppressing vortex shedding, thereby significantly reducing ship navigation resistance and enhancing lift. The study reveals that the aerodynamic performance of exhaust turbine sails is jointly influenced by oncoming flow conditions, suction power, and structural parameters, necessitating multi-objective optimization to achieve energy efficiency balance. The paper concludes by addressing key challenges in their marine applications and envisioning future directions for integrating these sails with emerging technologies, providing practical implications for promoting the green and low-carbon transformation of the shipping industry.

This study examines the deformation and stress characteristics of an aerospace turbine wheel under centrifugal, thermal and pressure loads. Design modification is focused on the neck of the disk, which is a structurally critical area. Increasing the neck thickness significantly reduces radial deformation from centrifugal force, while thermal and pressure-induced deformations remain nearly unchanged. Stress at the blade root is minimally affected by geometric changes, but the disk neck stresses decrease notably when the radius is between 3.25 and 4.00 mm. Beyond 4.00 mm, stress rises again due to a shift in the peak stress location to the rear side. Yielding is first observed at a 3.5 mm radius, where deformation is also reduced to 0.29 mm. This geometry thus offers the best balance between strength and deformation. The findings provide a method to determine optimal neck design for prescribed design conditions.

In this study, structural analysis was performed to select the optimal design shape through failure identification and design changes in turbine housing. Damage in the inlet flange is considered to be high cycle fatigue due to the vibration excitation in the engine full load test. Therefore, the FE analyses were performed natural vibration analysis and frequency response analysis for the initial shape and design change models. The stress magnitudes were obtained as a function of frequency through frequency response analysis according to engine vibration excitation. As a result, the dynamic stiffness of Case (1) increased by approximately 3.6% compared to the initial model, and Case (2) increased by 4.6%. In addition, the stress magnitude was greatly reduced in the design improvement. Therefore, the model with only the flange thickness increased is thought to be optimal design for securing the durability of the turbine housing.

페어리드 체인 스토퍼(Fairlead Chain Stopper, FCS)는 10MW급 부유식 해상풍력 발전기에 설치하기 위해 새롭게 개발된 탈착형 계류 시스템이다. 본 연구에서는 다양한 메타모델과 입자군집최적화 알고리즘을 이용하여 FCS의 구조설계에 대한 최적설계안을 탐색하 였다. FCS의 구조설계는 선급규정 설계하중조건을 산정하여 유한요소해석을 통해 수치해석적으로 평가하였고, 수치해석모델을 최적설계 에 연계하여 적용하였다. 최적설계의 수렴 효율성을 향상시키기 위해 반응표면모델, 크리깅, 체비쇼프직교다항식, 그리고 신경망과 같은 다양한 메타모델이 사용되었다. 최적설계에서 제한조건은 설계하중조건 별 응력을 고려하였고, 주요 구조부품의 두께 치수를 이산설계변 수와 연속설계변수로 각각 적용하여 목적함수인 최소중량설계를 달성할 수 있는 최적해의 특성을 비교하였다. 최적설계 알고리즘은 이산 설계변수의 최적해 탐색이 가능한 입자군집최적화가 적용되었다. FCS의 구조설계에 대해 신경망 기반의 메타모델이 적용된 경우에 4.72% 이하의 오차율로 최적해의 결정이 가능한 것으로 확인되었다.

With the increasing demand for energy conservation and emissions reduction in the shipping industry, suctionbased turbine sails have emerged as a novel wind energy utilization technology and have become a research hotspot. This study focuses on the aerodynamic performance of suction-based turbine sails with the aim of investigating the effects of suction intensity and suction port position on their aerodynamic characteristics. By employing Computational Fluid Dynamics (CFD) numerical simulations using the Re-Normalization Group (RNG) k–ε turbulence model and the SIMPLE algorithm, this study provides a detailed analysis of lift and drag coefficients, pressure distribution, and vorticity distribution under various combinations of suction intensity (γ) and suction port position (α). The results show that variations in suction intensity significantly affect the lift and drag characteristics of the turbine sail, while changes in the suction port position directly influence the attachment and separation behavior of airflow on the sail surface. Furthermore, a synergistic effect is observed between γ and α—their interaction not only alters the flow distribution but also plays a critical role in determining the overall performance of the turbine sail.By comprehensively considering the influence of these two factors, the study draws key conclusions for optimizing the design of suction-based turbine sail, providing valuable theoretical insights and technical guidance for their practical application in wind-assisted marine propulsion.

This study analyzes the aerodynamic and structural characteristics of an H-Darrieus vertical-axis wind turbine (VAWT) under varying inlet velocities using transient analysis. The k-ε turbulence model and six-DOF were applied to simulate urban environments in the flow analysis, while the structural analysis considered blade momentum of inertia and RPM conditions. The numerical results showed that the drag and lift forces increased by 60% and 53% respectively from the nominal wind speed to the cut-off wind speed conditions. Structural analysis indicated that the maximum Von-Mises stress in the blade did not exceed the yield strength of 69 MPa of PC-ABS, ensuring structural stability. However, the connecting rod exceeded the yield strength of SPCC 270 MPa, suggesting potential failure due to repeated rotational loads. This study confirms that materials with a yield strength of more than 1,100 MPa required for connecting rods to ensure reliable operation at high wind speed. These findings provide important insights for the design of robust VAWTs suitable for extreme environments.

In this paper, the design feasibility of the high-temperature rotation test jig for the operating state of gas turbine blades was confirmed through thermal structural analysis and modal analysis. The structural analysis model was composed of assembled blade, disc, cover, and shaft. Here, the disc was designed to be assembled with two types of blade. First, thermal analysis was performed by applying the blade surface temperature of 800°C. Next, structural analysis was performed at 3600 RPM, the normal operating condition, and 4320 RPM, the overspeed operation condition. Lastly, modal analysis was performed to examine the natural frequency and deformation of the jig. The FE analysis showed that the temperature decreased from the blade to disc dovetail. Additionally, both the blade and disc showed structural stability as the maximum stress was below the yield strength. Also, the first natural frequency was 636.35Hz and 639.43Hz at 3600RPM and 4320RPM, respectively, satisfying gas turbine design standards and guidelines. Ultimately, the designed test jig was confirmed to be capable of high temperature and rotation testing of various blades.

복합화력발전소는 가스터빈의 특성상 잦은 기동과 정지에 노출되며, 특히 배기부의 케이싱은 고온의 작동 유체가 실온 상태의 외 기와 만나기 때문에 볼트 체결부에서 열 피로 파괴가 발생한다. 비용과 시간의 효율성을 위해 운전에 경미한 영향을 미치는 균열 부위 는 용접 보수 작업 후 운용된다. 그러나 용접 과정에서 발생한 잔류 응력과 소성 변형이 케이싱에 미치는 영향을 조사하기 어렵기 때 문에 균열 보수 용접 케이싱의 피로 수명을 예측하여 운전을 얼마나 지속할 수 있는지 연구할 필요가 있다. 본 연구에서 유한요소해석 과 피로해석을 순차적으로 수행하여, 운전 조건에 따른 응력 및 변형률 진폭을 기반으로 피로 수명을 계산했다. 균열이 없는 건전 케 이싱에 비해 균열 보수 용접 케이싱은 피로 수명이 최대 32% 감소했다. 또한 다양한 균열 형태를 고려하여 8가지 크기의 용접 비드를 사용했으며, 폭과 높이가 줄어들고 길이가 길어질수록 피로 수명이 감소하는 경향을 보였다.

The turbine wheel plays a crucial role in operating turbines, and with recent advancements in technology, the performance requirements for turbine wheels have significantly increased. Consequently, it is essential to predict failure speeds, as turbine wheels must maintain high stability and reliability under harsh operating conditions. In this study, only the centrifugal loads generated by rotati were considered, excluding conditions such as temperature and pressure. A round-shaped fuse section was applied to the turbine wheel, and the stresses induced by variations in shape were analyzed to predict failure speeds. The results obtained using the Hallinan criteria were compared with the results from finite element analysis (FEA) to validate the predicted failure speeds, showing good agreement between the two methods.

최근 개발 및 상용화가 되는 해상풍력발전기의 용량이 15MW로 증가하면서 나셀 중량의 증가와 함께 블레이드와 타워의 크기 가 증가하고 있다. 원통 형상의 타워는 단순한 구조 형상을 갖고 있지만 블레이드가 회전하면서 발생하는 추력과 모멘트, 나셀과 블레이 드의 자중 그리고 타워 자체가 받는 풍하중에 매우 안전하게 지지해야 하는 아주 중요한 구성 요소이다. 다른 요소에 비해 파손이 발생하 면 파생되는 손실 위험도가 매우 크고 풍력발전기 가격의 25%를 차지한다. 본 연구의 주요 대상은 풍력발전기 타워이며, 복잡한 시간 이 력 하중 조합에 의한 구조 안전성 평가를 더욱 직관적으로 검증할 수 있는 단순화된 평가법을 제안하고자 한다. 구조 안전성 평가를 위해 서 사용된 프로그램은 NASTRAN이며 적용 하중은 풍력발전기 해석을 통하여 계산된 면내 전단하중 정보를 적용하였다. 신속한 구조 안 전성 검토를 위하여, 복잡한 하중 조합 조건을 단순화하고, 극한하중과 좌굴 그리고 피로수명까지 순차적으로 검토하였다. 유한요소해석 법에 따른 최소 수명 지점인 can 용접부를 EUROCODE 3에 의해서 계산하면 112.5년으로 평가하며 변동 피로 하중을 고려하는 방식이 다르고, 코드에서는 경험 계수를 고려하고 있어서 직접 비교는 어렵지만 유사한 경향은 확인할 수 있었다. 연구를 통하여 제시된 면내 하중 조합법을 이용하면 이른 시일 안에 타워의 구조 안전성을 검증이 가능하며 이에 따라 최종중량에 대한 확신을 높일 수가 있다.

Hydraulic turbines can convert tidal current energy into electric energy, and the addition of a deflector cover to the turbine can improve the efficiency of the turbine's energy harvesting. The angle of the inlet section and the angle of the outlet section of the deflector will further affect the final energy-acquisition efficiency.A threedimensional numerical model for turbine flow field analysis is established, and the RNG k-ε turbulence model is selected by CFD method, and the best angles of inlet section and outlet section are analysed by the method of sliding mesh to obtain the best angle of inlet section and outlet section separately, and then three groups of angles are selected near the best angle of inlet section and outlet section to make orthogonal comparisons. The energy acquisition efficiency of the turbine is calculated at different angles of the inlet and outlet sections of the deflector, and the turbine streamline distribution, velocity and pressure maps are analysed with and without the deflector.The study shows that the deflector can play the role of convergence of the downstream flow, which can improve the efficiency of the turbine energy acquisition, and the maximum energy acquisition efficiency is at the inlet angle of 29° and the outlet angle of 40 °, and the maximum energy acquisition efficiency can be improved by about 32 percent.

In alignment with South Korea's “3020 Renewable Energy Expansion Plan,” this study focuses on the developing large-scale floating wind turbines. It addresses the challenges of increased size and cost in floating structures for wind turbines over 10MW. This paper details the preliminary design of a novel floating substructure utilizing composite materials(ie, EVA). Structural analysis was performed using ABAQUS, accounting for both typical and extreme wind conditions. Results from the analysis validate that the substructure design is adequately feasible for implementation.

본 연구에서는 Monopile 방식 풍력발전기 강구조물의 부식을 방지하기 위하여 S355 steel의 표면 거칠기에 따른 용사 코팅 상태에 관한 연구를 수행했다. 일차적으로는 시편별 서로 다른 표면거칠기를 부여하기 위해 밀링머신에 페이스 커터를 결합하여 시편별로 다른 조건의 Ra값 기준 표면거칠기를 부여했다. 실험 조건으로는 시편 가공 시 4가지의 회전속도(60, 400, 1200, 2000 rpm), feed rate 150(mm/min) 조건을 선정했다. 2차로는 와이어 용융 방식의 아크 용사 코팅을 실시했다. 코팅 조건으로는 분사 거리 200mm, 전압 24V, 전류 120A, 분사 압력 5bar, 와이어 삽입 속도 30g/mm, 와이어 직경 2mm이다. 용사 코팅 후 FE-SEM으로 표면을 관찰한 결과 모든 시편의 S355 면과 코팅층(아연-알루미늄) 사이에 유격이 발생하지 않고 성공적으로 안착이 되었음을 확인할 수 있었다.

As the capacity of renewable power generation facilities rapidly increases, the variability of electric power system and gas turbine power generation is also increasing. Therefore, problems may occur that require urgent repair while the gas turbine rotor is stopped. When the gas turbine rotor turning is stopped and then restarted, if the turning period is not appropriate, severe vibration may occur due to rotor bending. As a result of the experiment, it was confirmed that normal operation is possible when the gap data measured at the start of rotor turning after maintenance work is similar to the existing value. And the vibration value at the start of rotor turning was lower as the rotor temperature was lower or the stop period was shorter.

In a steam turbine system for nuclear power plant, the exhaust loss consists of leaving loss, hood loss, turn-up loss and restriction loss. The exhaust loss during rated power operation of steam turbine equipment is inevitable, but it can be optimized by several factors such as last stage blade length, condenser vacuum and steam velocity. In this paper the relationship between the exhaust loss and electrical output of domestic nuclear power plants was quantitatively evaluated, and ways to reduce this loss were considered.