Numerical analysis for a proposed hybrid system with single HAWT,double HATCT and vertical oscillating wave energy converters on a single tower

South Korea has huge renewable energy potential that has been to some extent and can be further extracted to reduce its heavy reliance on fossil fuels. This project focuses on ocean and coastal wind resources available in the south-western regions of Korea that are currently being monitored and found to have huge potential. The project will propose a new concept of wind, tidal current and wave energy converting systems combined together that can boost output power capacity at a single location also making it easier for grid connection. Wind turbines nowadays have been quite efficiently developed and implemented throughout the world both onshore and offshore. However, tidal current and wave energy have yet more room for improvement. The current study will combine the offshore wind turbine (HAWT) system with two tidal current turbines (HATCT) both in horizontal axis classification on a single tower. It will further discuss on adding a wave energy converter in between the wind and tidal current turbines. Optimization of the tower is also a minor part of this study. The structural analysis of the main tower, which is the main focus of the study, is investigated by dynamic response analysis to check its feasibility for combining the three types of renewable energy converters on one support. Actual extreme conditions of the wind, ocean currents and waves are simulated using ANSYS CFX fluid flow analysis. The results are used for conducting a one way FSI analysis assuming a rigid structure to verify the safety of the system.

     

Hydraulic design and performance analysis on a small pump-turbine system for ocean renewable energy storage system

Korea has a myriad of islands in the south western coast that extensively rely on diesel generators for power production, which increase cost and environment pollution. The small hydro pump-turbine system for ocean renewable energy storage system is a kind of hybrid system that can reduce the usage of diesel generators and help to contribute to the environment in a positive manner by helping to reduce carbon emissions. The study focuses on initial hydraulic design and numerical analysis of a 30 kW-class pump-turbine system for energy independent islands in South Korea. The purpose of the study is to propose an ocean renewable energy storage system using a small pump-turbine system working with seawater. A 30 kW-class pump-turbine does not require a large head; approximately 30 m is sufficient for the design and application. Several other renewable energy systems like wind turbines, tidal turbines, wave energy converters and solar energy could be used to make a hybrid system with pump-turbine. The initial design achieved more than 85 % efficiency in both pump and turbine modes. However, further optimizations of the impeller blade shape and number of guide vane and stay vanes could improve the overall efficiency of the system.     

Suppression of unsteady swirl flow in the draft tube of a Francis hydro turbine model using J-Groove

The pressure fluctuations of the turbines are caused by the swirl component in the draft tube, which is an undesired phenomenon that needs to be improved when the turbine operates in the off-design condition. In order to avoid these kinds of unsteady flow phenomena, a technology of J-Groove on the draft tube wall is investigated by numerical method. The validation test of performance is conducted to compare the result of numerical and experimental methods. The steady and unsteady state analyses are conducted to investigate the internal flow of a Francis hydro turbine model draft tube with and without J-Groove. The swirl flow in the draft tube is significantly suppressed by the J-Groove installation. Moreover, according to the unsteady state analysis, the amplitude of pressure fluctuation in the draft tube is reduced effectively by the J-Groove.

     

The effect of runner blade loading on the performance and internal flow of a Francis hydro turbine model

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. It is effective and successful to design a Francis turbine runner blade with good performance by one-dimensional hydraulic design method. For the one-dimensional hydraulic design, the runner blade angle at leading and trailing edges can be defined by calculation of Euler’s head. Design of the runner blade profile at several cross sections is needed to design a runner shape. In this study, there are three different blade loadings conducted to compare the internal flow characteristics and performance. The result shows that the front loading achieves the best efficiency in comparison to other loadings, which is good at suppressing the loss at draft tube.     

N-乙酰半胱氨酸通过调控EGFR/MAPK信号通路对慢性阻塞性肺疾病气道黏液高分泌的作用研究

目的:研究N-乙酰半胱氨酸（NAC）通过调控表皮生长因子受体/丝裂原活化蛋白激酶（EGFR/MAPK）信号通路对慢性阻塞性肺疾病（COPD）气道黏液高分泌的作用。方法:30只雄性清洁级Wistar大鼠,随机分为3组,各10只,对照组为健康大鼠,模型组为COPD气道黏液高分泌大鼠,NAC组自造模起予以3 mmol/kg 100 μL NAC,共30 d,比较各组肺组织病理结果、气道阻力（RL）和动态顺应性（Cdyn）、血气分析［动脉血二氧化碳分压（PaCO2）、动脉血氧分压（PaO2）］、黏膜层厚度/支气管壁厚度（Reid指数）、气道上皮阳性杯状细胞/总上皮细胞数、EGFR/MAPK信号通路蛋白［EGFR、磷酸化应激活化蛋白激酶（p-JNK）/总JNK、磷酸化-丝裂原活化蛋白激酶p38（p-P38MAPK）/总P38、磷酸化细胞外调节蛋白激酶（p-ERK）/总ERK、黏蛋白5AC（MUC5AC）］表达。结果:对照组上皮细胞、气道黏膜上皮、黏膜下腺体、支气管管壁无异常,管腔无分泌物;模型组肺间质血管充血,肺泡间隔变薄、断裂,相邻肺泡融合形成较多囊腔,上皮细胞存在明显增厚、增生、坏死脱落,黏膜下腺体肥大,杯状细胞增生,支气管周围炎性细胞浸润明显,管壁平滑肌束萎缩、断裂;NAC组与对照组相比,存在异常,但与模型组相比,各病理特征均减轻;模型组Cdyn、PaO2低于对照组,RL、PaCO2高于对照组（P＜0.05）;NAC组Cdyn、PaO2高于模型组,RL、PaCO2低于模型组（P＜0.05）;模型组Reid指数、阳性杯状细胞/总上皮细胞数高于对照组（P＜0.05）;NAC组Reid指数、阳性杯状细胞/总上皮细胞数低于模型组,但与对照组相比,差异仍具有统计学意义（P＜0.05）;模型组p-JNK/JNK、p-P38/P38、p-ERK/ERK、MUC5AC高于对照组（P＜0.05）;NAC组p-JNK/JNK、p-P38/P38、p-ERK/ERK、MUC5AC低于模型组,但与对照组相比,差异仍具有统计学意义（P＜0.05）。结论:N-乙酰半胱氨酸能通过抑制EGFR/MAPK信号通路表达,改善慢性阻塞性肺疾病支气管黏液腺体增生、杯状细胞广泛化生,抑制气道黏液高分泌状态,提高大鼠肺功能。