石化设备抗震抗风动力性能分析和安全性鉴定

石油化工设备类型繁多，形体复杂，其中包括现行抗震鉴定规范中有相关规定的常规设备，也包括一些在抗震鉴定规范中尚无规定的特殊设备。文章以独山子炼油厂的石化设备为例，简要介绍了它们的抗震分析方法和鉴定结果，对其中的高耸结构还进行了抗风分析。     

汽车环境风洞地面区域流场数值仿真

目的 探究汽车环境风洞地面区域流场规律,获取风洞边界层抽吸装置的最佳抽吸率和底盘测功机对风洞地面区域边界层厚度、风速、总压和静压的影响规律,并比较MRF法和旋转壁面法对底盘测功机转毂转动模拟的精度。方法 运用计算流体动力学方法对汽车环境风洞流场进行数值仿真计算。结果 边界层抽吸装置对应于喷口风速120 km/h时的最佳抽吸率为0.048。底盘测功机区域总压呈现下降趋势。相比于存在底盘测功机,汽车环境风洞无底盘测功机时,底盘测功机区域内相同位置的边界层厚度会增加1.28～12.22 mm。在前转毂的前侧、上侧、后侧和后转毂的上侧和后侧会有一个高风速区域,区域内风速比设定风速高1%～4%,与无底盘测功机相比,区域内静压值低0.32～46.02 Pa。在前后转毂前侧和后侧与地面相连接的凹部会有一个低风速区域,区域内风速比设定风速低1%～5%,与无底盘测功机相比,区域内静压值高0.08～49.34 Pa。底盘测功机转毂的转动会使附近区域的地面边界层厚度变大。在前转毂前侧,采用旋转壁面法进行模拟比MRF法地面边界层厚度增加近8 mm,而在其他位置,2种模拟方法对边界层厚度的模拟差别在1.5 mm...     

城市区域风易损结构风灾损失分析研究

城市风易损结构在台风等强风灾害下的损坏及倒塌将严重影响城市社会的运行安全。以户外广告牌作为典型城市风易损结构物,提出基于结构参数的风易损结构抗风分析方法。针对城市广告牌分布具有的区域空间分布特征及局部风效应,以城市区域风灾为研究对象,结合区域数值风场模拟分析对城市区域风灾损失进行了分析研究。     

板锥网壳结构的风振响应分析

板锥网壳结构是一种受力性能合理,技术经济效益良好的新型空间结构形式。采用谐波法模拟了Daven-port脉动风谱;采用时程分析法对板锥网壳结构进行了风振响应时程分析,并对板锥网壳结构的风振响应特性进行了全面和深入的研究,为板锥网壳结构的抗风设计提供理论上的依据,得出了可应用于工程实践的重要结论。     

多因素下开洞口煤仓风致积雪CFD模拟及拟合研究

为解决结构设计时开洞口圆形煤仓表面无法确定荷载分布系数问题,使用计算流体力学软件研究了开洞口煤仓不同跨度下风向角、积雪厚度及矢跨比变化下屋面积雪不均匀分布情况,提出了针对此种特殊结构的屋面积雪值拟合公式。研究结果表明:此公式拟合准确度高,屋面积雪值随风向角和积雪厚度增大而变大,风向角对积雪值影响极大,矢跨比影响下屋面积雪值变化较为复杂,且风向角和矢跨比2种参数相互影响,不应单一考虑矢跨比对球壳屋面积雪值的影响。     

煤巷顶板围岩结构承载能力弱化分析

为了揭示煤巷顶板围岩承载能力的弱化机理,结合已有的研究成果,建立巷道顶板三向承载梁结构承载弹塑流弱化分析模型,确定三向承载梁结构承载状态的分析方法,提出用围岩塑性区深度、宽度、长度作为评价巷道围岩承载的弱化分析指标,研究围岩性质、支护强度、采动应用等诱导因子对煤巷顶板结构承载能力弱化分析指标的影响规律。研究结果表明:随着围岩强度的提高、支护强度的增加、扰动应力的减小,弱化分析指标呈似线性减小的变化规律,且减幅由大到小排序为塑性区长度Sy,宽度Sx和深度Sz,同时提高围岩强度、支护强度,减小采动作用应力,煤巷顶板弱化分析指标的减小程度显著高于单因子的改善。     

“It's easy to throw rocks at a corporation”: wind energy development and distributive justice in Canada

In places like Canada, fast-paced wind turbine development combined with policy that limits local decision-making power has resulted in strong opposition to specific projects. Some studies suggest that anti-wind sentiment is tied to inadequate financial benefits – especially sharing at the local level. Thus, ideas of distributive economic justice have received traction, particularly in the form of praise for community-based development models. This paper reports on the findings from a mixed-methods study concerning preferred distributive justice elements in rural communities in Ontario (technocratic-based model) and Nova Scotia (community-based model) living with turbines. Residents’ perceptions of economic benefits are nuanced, but unlike other studies, this empirical work shows that both the fair distribution and the amount of local benefits are important predictors of project support. Yet, concerns around the fair distribution of benefits dominate in a regression on the adequacy of those benefits. A variety of interview and survey findings further point to the strength of traditional, profit-sharing community-based models for distributing benefits, but also more novel ideas including lowered electricity bills and tax rebates in areas home to turbines.     

Starting improvement of micro-wind turbines operating in low wind speed regions

The study deals with the design and optimization of external and internal geometry of micro-wind turbines blades. A specified objective function which consists of the power coefficient and the starting time was defined and the genetic algorithm optimization technique in conjunction with the blade-element momentum theory was adopted to find the geometry of the blades including the distributions of the chord, the twist angle and also the shell thickness. Moreover, the allowable stress of the blades was considered as a constraint to the objective function. Results show that a reasonable compromise is achievable such that the starting time of the blades reduces noticeably in return for a small drop in the power coefficient. The significant improvement of the hollow blades over the solid ones indicates that the power coefficient and the starting performance could be improved through the appropriate distributions of the considered decision variables, i.e. the chord, the twist angle and also the shell thickness.     

Wind energy potential analysis for Thailand: Uncertainty from wind maps and sensitivity to turbine technology

Rapid development of wind energy has been witnessed in Thailand. However, different wind resource maps (over land) have brought great uncertainty to wind energy planning. Here, four important mesoscale wind maps were considered: DEDP (2001), World Bank (2001), Manomaiphiboon et al. (2010) of JGSEE, and DEDE (2010). The wind maps were first harmonized to a common grid at 100 m and then compared. The earlier wind maps (DEDP and World Bank) are shown to represent the lower and upper limits of predicted speed, respectively, while JGSEE and DEDE tend to be more moderate with predictions statistically closer to observations. A consolidated wind map was constructed based on their median and shown to have the best prediction performance. It was then used for the technical potential analysis, in which three large (2-MW) turbine models (two conventional and one designed for low wind speed) were considered. By GIS techniques, any land areas not feasible for large wind turbines were excluded, and the corresponding overall onshore technical potential ranges between 50 and 250 GW, depending on map and turbine model. Considering only economically feasible turbines (with capacity factors of 20%) and the median-based map, the final technical potential equals 17 GW when using the low-wind-speed model but is reduced to 5 GW with the conventional models, adequately meeting the national wind energy target of 3 GW by the year 2036. The results suggest a strong sensitivity of estimated technical potential to turbine technology and a suitability of low-wind-speed turbines for wind conditions in Thailand.     

Wind energy and natural ventilation potential of a wind catcher in Yazd – Iran (a long-term measurement)

When designing energy efficient buildings it is useful to study existing climate—responsive building typologies. The wind towers or wind-catchers of Yazd city in Iran are typical examples of such a typology. Although many previous studies have investigated the performance of various types of wind catcher systems, studies based on a long-term real-life measurement can be rarely found. In this study a long-term whole year monitoring campaign on an existing full scale four sided wind catcher in Yazd was carried out in 2014–2015. Three prevailing wind directions were identified and the measured on-site wind speeds were used to estimate the wind induced natural ventilation potential of the tower. A shaft/tower airflow performance index was developed. The monitoring results were compared to the ASHRAE Standard 62:2001 ventilation rate requirement. Results show that the total ventilation rate of the wind tower surpasses the ASHRAE Standard requirements. Furthermore it shows that the shafts are exposed to the prevailing wind directions perform better. For more effective natural ventilation a wind tower with adaptable openings/shafts are proposed.