Validation of a three-dimensional viscous–inviscid interactive solver for wind turbine rotors

MIRAS is a newly developed computational model that predicts the aerodynamic behavior of wind turbine blades and wakes subject to unsteady motions and viscous effects. The model is based on a three-dimensional panel method using a surface distribution of quadrilateral singularities with a Neumann no penetration condition. Viscous effects inside the boundary layer are taken into account through the coupling with the quasi-3D integral boundary layer solver Q³UIC. A free-wake model is employed to simulate the vorticity released by the blades in the wake. In this paper the new code is validated against measurements and/or CFD simulations for five wind turbine rotors, including three experimental model rotors [20–22], the 2.5 MW NM80 machine [23] and the NREL 5 MW virtual rotor [24]. Such a broad set of operational conditions and rotor sizes constitutes a very challenging validation matrix, with Reynolds numbers ranging from 5.0⋅10⁴ to 1.2⋅10⁷.     

基于致动线模型的风力机尾流场数值模拟

本文基于致动线模型求解三维Navier-Stokes方程的方法,对NTNU的"BlindTest1"风力机尾流场进行了数值模拟。该方法避免了求解实际叶片的表面边界层,无需使用动网格,从而大大降低了网格量和计算时间,非常适用于尾流场的模拟。该文所有计算均基于OpenFOAM自定义的求解器ALMpisoFoam。推力和功率的计算值与实验值吻合得很好,验证了求解器的正确性。3个典型叶尖速比下的轴向诱导因子、湍动能和尾涡结构等也在文中进行了简要分析。     

Increase of the Density of the Silver Image during Storage after Processing

The light-sensitive layer consists of iron (III) acctylacetonate which is embedded into the polymer Saran. Image dots of 10 μm size are generated by the irradiation with a focused laser beam. They are sharp edged and black and appear on a bright, transparent background. The required exposure per dot amounts to approximately 250 mJ/cm². A specimen of type was recorded at a rate of 1000 lines/min, without any after-treatment being necessary.     

Feasibility assessment of a container ship applying ammonia cracker-integrated solid oxide fuel cell technology

The maritime industry has entered its pathway of decarbonization. To achieve the IMO's ambitious goals of an absolute emissions reduction of 50% by 2050, and a 70% carbon intensity reduction by 2050 compared to the 2008 level, various options for the adoption of technologies and alternative fuels are considered by the market stakeholders.Ammonia, one of the most promising alternative marine fuels has long been considered to reduce carbon emissions. And solid oxide fuel cell is expected to transform ship propulsion technology in the future due to its high utilization of fuels. In this paper, a feasibility study is performed to assess the application of an ammonia cracker-integrated solid oxide fuel cell (hereafter as Ammonia SOFC) system on an ocean-going vessel through a detailed CAPEX, FuelEX, OPEX, Carbon tax, and carbon emission analysis. Comparison is made with direct ammonia, LNG and conventional fuels fired heat engines. The result concludes that it can be economically viable to apply to deep-sea shipping, compared to other marine fuels and propulsion technologies.     

A new ship energy management algorithm to the smart electricity grid system

In this paper, a new energy management algorithm has been suggested for the ships connected with alternative energies considering the smart electricity grid features. The algorithm focuses on the use of optimum energy source on the shipboard based on the priorities of authorities such as the most economic, environmental, or both criteria at the ports. The algorithm is performed in MATLAB, and several case studies are simulated to validate the results. The 5 maritime nations, which are at different regions: United States, Belgium, Turkey, China, and Australia, are taken into account in the case studies. The actual data of a bulk carrier ship have been used to achieve tangible results in the simulations. The results of the case studies are compared to determine the changes of energy cost and released emission to meet demand of electricity on the ships. Capital cost of the proposed concept is also given to make an economic evaluation. The results show that the ship energy management algorithm provides the significant economic and environmental advantages. This paper aims to contribute to the importance of the ships in the smart electricity grid concept for the maritime and electricity sector representatives.     

Consideration of influence factors between small‐scale specimens and large components on the fatigue strength of thin‐plated block joints in shipbuilding

Shipbuilding in blocks, as being usual on all larger shipyards, requires that the blocks will finally be welded together manually or semi‐automatically, that is, with butt‐welds in transverse direction that have to withstand relatively high dynamical loads. Modern shipbuilding aims at lightweight construction with thin plates that may have a plate thickness down to 4 mm. Previous investigations showed that manually produced butt‐welds in such thin structures did not reach the calculated fatigue life as required in the rules. Up to the present, this problem has not yet been solved, and it is questioned if all influence factors on the fatigue behaviour of real structures are correctly considered as no damage cases at butt joints that are known yet. In the investigation described here, results from small‐scale specimens tested with cyclic loads will be transferred to large components, considering the effects of recorded pre‐deformations induced by welding as well as measured differences in residual stresses between small‐scale specimens and large components, thus clarifying how far for instance a detrimental stress ratio should be taken into account by the rules for thin plates.     

Investigations for indications of deliberate blasting on the front bulkhead of the ro-ro ferry MV ESTONIA

The roll-on-roll-off passenger ferry MV ESTONIA sank during the night of 28 September 1994 in the Baltic Sea. In October 2000, divers recovered two palm-sized test pieces from the front bulkhead of the wreck. The investigators analysed these specimens to determine whether there were any indications of deliberate blasting. Since the wreck had been submerged for almost six years, it was clear that chemical traces would not be present on the surfaces of the test pieces. Therefore, the investigators performed comparative tests on shipbuilding steel to find a microstructural criterion that exclusively characterises a blast. The shipyard Jos. L. Meyer, Germany, had built the ESTONIA and supplied shipbuilding steel plates similar to that used for building the vessel in 1979/1980. The comparative tests comprised mechanical tests, shot peening tests and blasting tests using different explosives. Testing demonstrated that blasting always formed twinned ferrite grains in the microstructure over the whole cross-section of each of the 8 mm thick comparative plates. Although one of the original test pieces of the ESTONIA showed deformation twins, this was only confined up to 0.4 mm underneath the surfaces and not spread over the whole cross-section. Comparative shot peening tests produced the very same pattern of subsurface deformation twins. Therefore, the twins detected in the microsection of the test pieces of the ESTONIA wreck traced back to the shot peening process performed by the shipyard in 1979/1980 and not to a deliberate blast.     

基于Android系统的船舶行业移动办公的研究实现

基于现代网络技术的发展和移动终端的发展前景,为了更好地发展船舶行业,从而实现移动办公,本文采用了智能移动终端开发了一款查询软件,主要从用户的角度进行功能分析、权限设计、接口设计和测试。通过测试,可以看出该软件可以实现远程访问数据库,查询信息和收发信息。在一定程度上,这一功能的实现推进了移动办公的速度,同时加速了船舶行业的数字化进程,如果把该软件推广到其他行业,依然可以完成相似的功能,有更广阔的发展前景。     

提高50Mn-C材质船用锻件质量的措施

本文主要介绍了50Mn-C材质船用锻件在生产过程中,有效控制了锻件草状波、性能不合格等问题的发生,提高了锻件一次探伤及性能的合格率。