Best location of the small wind turbine around a single high-rise building

This research is a three-dimensional investigation about the aerodynamic interaction between the wind flow and a single high-rise building. In order to find location(s) with high potential of velocity around the building, a wide variety of wind speeds ranging from 2 to 10 m/s is studied. On the other hand, a high-rise building with the ratio of height to width of H/W = 3 is considered. Computations are performed numerically by means of the finite volume approach. Several results are obtained in the present numerical study. For example, it is found that due to wind-structure vertical interaction, locations with enhanced velocities are developed on the building roof in which the rate of this enhancement increases with increasing the wind speed. In addition, over the building, “lines C and D” are realized as the best locations having high power potentials and low turbulence intensities. In addition, lateral wind-structure interaction revealed that for all wind speeds, location of L/W = 0.5 is the best for the small wind turbine installation.     

Numerical and experimental research on multi-stage pump as turbine system

Recently, researches on pump as turbine (PAT) have been one of the hot issues in fluid machineries. Of these hydraulic turbines, multi-stage PATs are widely used in industrial fields. However, most attentions have been paid on performance of the single-stage PATs and the turbines themselves. In this paper, a potential multi-stage PAT system with load pump was investigated numerically and experimentally. The match relations between PAT and load pump were explored by theory, and an analytical method to predict performance of PAT system was proposed in addition. Computational fluid dynamics method (CFD) was adopted to study the performance characteristics of PAT under a constant rotation or certain head. The operational rules of multi-stage PAT system were analyzed in both constant and variable speed that confirmed the prediction of system performance. The results could give guidance to choose a proper load pump and promote efficiency of PAT system.     

Amazon dams and waterways: Brazil’s Tapajós Basin plans

Brazil plans to build 43 “large” dams (>30 MW) in the Tapajós Basin, ten of which are priorities for completion by 2022. Impacts include flooding indigenous lands and conservation units. The Tapajós River and two tributaries (the Juruena and Teles Pires Rivers) are also the focus of plans for waterways to transport soybeans from Mato Grosso to ports on the Amazon River. Dams would allow barges to pass rapids and waterfalls. The waterway plans require dams in a continuous chain, including the Chacorão Dam that would flood 18 700 ha of the Munduruku Indigenous Land. Protections in Brazil’s constitution and legislation and in international conventions are easily neutralized through application of “security suspensions,” as has already occurred during licensing of several dams currently under construction in the Tapajós Basin. Few are aware of “security suspensions,” resulting in little impetus to change these laws.     

Observations of relative humidity in the near-wake of a wind turbine using an instrumented unmanned aerial system

Simulation, modeling, and limited observations have shown that wind farms have an impact on the near-surface atmospheric boundary layer as turbulent wakes enhance vertical mixing of momentum, heat, and moisture. The few observational datasets that do exist lack high spatial resolution due to their use of a limited number of meteorological sensors or remote sensing techniques. This study utilizes an instrumented small unmanned aerial system to gather high-resolution in situ field measurements in order to differentially map near-wake changes to relative humidity. Observations show that downstream relative humidity is differentially altered in the vertical, spanwise and downstream directions.     

Reconstructing historical trends of Berre lagoon contamination from surface sediment datasets: influences of industrial regulations and anthropogenic silt inputs

These last decades, the Berre lagoon (in southeastern France) has been deeply affected since the 1930s by strong inputs of contaminants associated with industrial development and since 1966 by huge inputs of freshwater and silts due to the installation of a hydroelectric power plant. Surveys of the surface sediment contamination have been sparsely performed since 1964 for management and research purposes. These surveys were performed by various laboratories that investigated different chemicals and sampling areas using different analysis protocols. Therefore, the available data are disconnected in time and space and differ in quality. In order to reconstruct coherent time series of sediment contamination from this heterogeneous datasets and to discuss the influences of industrial and hydroelectric discharges we used a statistical approach. This approach is based on Principal Component Analysis (PCA) and Fuzzy clustering analysis on data from one extensive survey realized on surface sediments in 1976. The PCA allowed identifying two geochemical indexes describing the main surface sediment geochemical characteristics. The fuzzy clustering analysis on these indexes allowed identifying sub-areas under the specific influence of industrial or hydroelectric discharges. This allowed us to reconstruct, for each sub-area, a coherent and interpretable long-term time series of sediment contamination from the available database. Reconstructed temporal trends allowed us to estimate: (i) the overall decrease of sediment contamination since the mid-1970 attributed to industrial discharge regulations enacted at this period and (ii) the dilution of the concentrations of sediment bound contaminants induced by the hydroelectric power plant and its associated particulate matter inputs.     

某850kW水平轴风力发电机机舱火灾模拟与分析

采用火灾动力学模拟器软件和性能化防火设计理论,基于实际事故案例分析,设计针对某850 kW水平轴风力发电机机舱的典型火灾场景,建立池火灾模型,对额定风速(13 m/s)下机舱内该类型火灾的发生和发展过程进行研究,模拟计算机舱内火灾的热释放速率、温度场和速度场等参数,探讨进气口风速对火灾热释放速率和温度场等的影响。结果表明:封闭条件下,从齿轮箱底部发展起来的油池火灾热释放速率在62.4 s时达到最大值(757 kW),持续燃烧93 s后降至0;齿轮箱附近部件遭受火灾破坏最为严重,喷射油料二次燃烧导致火强度变大并加剧了火灾的破坏程度。额定风速下,齿轮箱附近软管喷射油料未出现二次燃烧现象,但火灾后期热释放速率在335 s内达到4 000 kW;以火源为分界面,火源前方区域温度(406~567℃)明显高于后方区域温度(177~279℃);顶部通风口承受全部热流,机舱罩顶部温度最终达到930℃,并出现轰燃。     

Analysis of emission characteristics of gas turbine engines with some alternative fuels

The paper concerns the comparative analysis of combustion characteristics of different alternative fuels such as Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK), cryogenic methane, bioethanol, biomethanol, biobutanol, dimethyl ether, biodiesel and conventional aviation kerosene Jet-A as well as analysis of emissions of NO_x, CO, CO₂, H₂O, HNO_y (y = 2,3) and organics for gas turbine engine operating on these fuels. The analysis has shown that the usage of all considered alternative fuels results in the increase of H₂O emission, compared to kerosene-fueled combustor, and, as consequence, in the growth of water vapor supersaturation that can increase the rate of the H₂O vapor condensation and enhance the formation of contrails and cirrus clouds in the atmosphere. The usage of all considered alternative fuels except FT-SPK, cryogenic methane and dimethyl can increase the CO₂ emission compared to using of kerosene. Emission of N-containing species can be reduced upon the usage of considered alternative fuels, except dimethyl ether, for which one can expect the increase in the emissions of HNO₂ and HNO₃ approximately by 10%. The emission of CO decreases for all fuels except biodiesel. The major decrease can be achieved upon the replacement of kerosene to bioethanol.     

基于Excel和VBA的汽轮机排汽焓求解

热力性能测试和计算是火电机组热经济性分析的基础,其中排汽焓的确定不容忽视。在分析比较目前各种在线和离线计算方法的基础上,介绍了利用Excel的矩阵函数,配合少量VBA代码,快速求解汽轮机排汽焓的具体方法。该方法以汽轮机及回热系统能量平衡为基础,遵循GB 8117-1987要求并参考ASME PTC6-1996规范。实例计算表明,该方法编程简单,计算快速,可满足汽轮机热力性能试验报告等的需要。     

台风型风电机组塔架轻量化设计研究

目的实现台风型风电机组塔架的轻量化设计。方法对风电机组台风环境载荷工况和台风期运行控制策略进行研究,提出在基于GB/T 31519—2015《台风型风力发电机组》的台风型风电机组基础上,开发台风控制策略,使机组在台风期间持续处于对风状态。结果利用BLADED软件计算机组各关键部位的载荷,结果表明,台风控制策略降低了23.5%的机组塔基载荷,重新设计塔架,塔架质量降低了13%,实现了塔架轻量化设计,单个风电场节省约416万元,具有很好的经济效益。通过机组现场实测,在摩羯台风期间,采用台风控制策略的台风型风电机组塔基载荷,Mxy理论仿真值与实测值的相关性达94.1%,高度一致。结论验证了理论仿真计算的准确性和轻量化塔架应用的可行性,助力于我国风力发电行业沿海地区及海上型风力发电机组的发展。     

Brazil’s Samuel Dam: Lessons for Hydroelectric Development Policy and the Environment in Amazonia

Brazil’s Samuel Dam, which formed a 540-km² reservoir in the state of Rondônia in 1988, provides lessons for development decisions throughout Amazonia and in other tropical areas. The decision to build the dam was heavily influenced by its role in the political strategies of key decision makers. Samuel illustrates both impacts and benefits of electricity supply and the dilemmas facing decision makers regarding the various options for planned electricity generation. Environmental costs included flooding forest and stimulating illegal logging activity throughout western Amazonia because of an exception opened for Samuel in Brazil’s prohibition of export of raw logs. Samuel emitted substantially more greenhouse gases than would have been emitted by generating the same amount of electricity from oil. Contamination of fish in the reservoir resulted from methylation of mercury present in the soil. Social costs of the dam included resettlement of 238 families of farmers; impacts on indigenous people were indirect. Mitigating measures included faunal rescue and creation of a forest reserve. The lessons of Samuel include the need to consider a full range of alternatives prior to making decisions in practice and the importance of adhering to the logical sequence of decision making, where information is gathered and compared prior to the decision. It also shows the need to maintain flexibility when the costs and benefits of different alternatives change significantly over the course of the project’s planning and execution, as occurred at Samuel.