Wind turbine performance under icing conditions

The wind energy market is in full growth in Quebec but technical difficulties due to cold climate conditions have occurred for most of the existing projects. Thus, icing simulations were carried out on a 0.2 m NACA 63 415 blade profile in the refrigerated wind tunnel of the Anti‐icing Materials International Laboratory (AMIL). The shapes and masses of the ice deposits were measured, as well as the lift and drag forces of the iced profiles. Scaling was carried out based on the 1.8 MW–Vestas V80 wind turbine technical data, for three different radial positions and two in‐fog icing conditions measured at the Murdochville wind farm in the Gaspé Peninsula. For both icing events, the mass of ice accumulated on the blade profile increased with an increase in the radial position. In wet regime testing (first icing event), glaze formed mostly near the leading edge and on the pressure side. It also accumulated by run‐off on the trailing edge of the outer half of the blade. In dry‐regime testing (second icing event), rime mostly accreted on the leading edge and formed horns. For both icing events, when glaze or rime accreted on the blade profile, lift decreased and drag increased. A load calculation using the blade element theory shows that drag force on the entire blade becomes too large compared to lift, leading to a negative torque and the stop of the wind turbine. Torque reduction is more significant on the outer third of the blade. Setting up a de‐icing system only on the outer part of the blade would enable significant decrease of heating energy costs. Copyright © 2007 John Wiley & Sons, Ltd.     

单轴船舶运动模拟摇摆台架设计

减摇鳍是最常用的船舶减摇设备之一,在减摇鳍设计制造完成后,或是进行研究时,通常通过台架试验测试减摇鳍的性能.摇摆台架的性能指标直接关系到试验的准确性,本文对摇摆台架的设计进行了介绍,硬件部分采用PC 可编程控制器的控制方式,上位机软件采用VB编写,实现了对台架的实时控制和船舶横摇运动结算.     

HFW焊管残余应力分析

采用小孔检测法研究了规格Φ406.4 mm×12.5 mm、钢级L415MB的HFW焊管残余应力的分布情况。试验结果表明,HFW焊管整体残余应力值较小,并且轴向残余应力大于环向残余应力,轴向和环向最大值分别约为母材屈服强度的38%和29%;HFW电阻焊焊缝及其附近区域的残余应力值低于管体区域,轴向和环向残余应力的变化范围分别约为母材屈服强度的24.5%~33.6%和16.4%~21.5%;HFW电阻焊管轴向和环向残余应力的差异呈周期性变化,距离焊缝15°附近时差异最小。试验结果对于HFW电阻焊管在长输管线的应用提供理论支持。     

Precision forging of spur gears with inside relief

Conventional closed-die forgings as applied to the forging of spur gears require high forging pressure. In this paper, a precision forging technology has been developed for the forging of spur gears with alloy steel (SCM415). The technology developed includes two steps in the forging process. Well-shaped products are forged successfully using a lower forging pressure than that of conventional forging. The accuracy of the forged spur gear obtained by the new precision forging technology is set nearly equal to that of a cut spur gear of the fourth and the fifth classes in the Korean industrial standard.     

预应力混凝土折线形屋架（04G415—1图集）施工的若干问题的讨论

24m折线形屋架构造特殊,屋架较大,侧向的稳定性差,屋架在张拉过程中易产生侧面弯曲,养护过程中易产生裂缝。结合某工程中24In预应力混凝土折线形屋架的施工,针对屋架的制作、张拉、安装等个几方面存在问题,对04G415—1图集提出优化建议。同时对几点需要讨论的问题包括裂缝的产生防治,上弦及下弦的箍筋设置提出了自己的意见。     

L415M管线钢焊缝横向裂纹产生原因与预防措施

为解决管道施工中L415M管线钢横向裂纹的难题,针对裂纹产生部位、方向和现场施焊情况,从焊接材料、冶金、工艺等方面进行了分析,判定了裂纹性质。分析表明,焊缝热裂纹产生是焊丝受潮与焊接工艺措施不当共同导致的,其中焊丝受潮是主因。根据裂纹产生原因,通过采取避免焊丝受潮、调整打底焊顺序、降低自保护焊热输入、调整焊工起弧位置以及拉大起弧间距等措施,避免了裂纹再次产生,保证了焊接接头的焊接质量和管道安全。     

湖南某钨多金属矿选钨新工艺研究

湖南某钨多金属矿采用磁选铁—浮选硫化矿—钨粗选—加温精选工艺流程回收其中的铁、硫化矿和钨,其中钨精矿品位65%以上,回收率在65%~70%,其中钨加温精选作业添加了大量的水玻璃,药剂成本高、能耗高、环保压力大。针对该问题,本文进行了详细的试验研究,最终推荐磁选铁—浮选硫化矿—钨粗选—钨粗精矿重选联合工艺流程,其闭路试验结果为钨精矿含钨65.89%、回收率72.09%。     

西部某压气站压缩机出口埋地管线外腐蚀原因分析

为了分析西部某压气站压缩机出口钢级为L415的埋地管线外腐蚀原因,对该管段进行了宏观检查、壁厚测量、理化检验、扫描电镜（SEM）、X射线衍射物相以及土壤等综合分析。结果表明,该段管线外腐蚀的直接原因为防腐层失效,钢管失去保护,裸露于外部环境,同时土壤中Cl-含量较高,易造成管体腐蚀,管道温度变化及管体与混凝土基座接触是腐蚀加速的间接原因。     

AVIA15S烟度仪在烟炱分散性试验台架上的应用

AVIA15S是滤纸式烟度计,它是检测柴油机排气可见颗粒物的仪器。文章重点介绍了AVL415S烟度仪的工作原理、适用范围及在烟炱分散性试验台架上的应用,目的在于能够使烟度仪在烟炱分散性台架上得到正确使用和维护,确保烟度仪有较好的使用性能、准确的测量烟度和较长的使用寿命。     

Improvement of photo-fermentative hydrogen production performance by expressing tetracycline resistance genes tetAR in Rhodobacter sphaeroides HY01

A typical expression plasmid, pRK415, was widely used to introduce cloned DNA fragment into a broad range of Gram-negative bacteria, including Rhodobacter sphaeroides. Tetracycline (Tc) is required for stable inheritance of the plasmid, but it is subject to photooxidation, inhibitory to the growth of the host strain. However, in this study, the introduction of pRK415 into R. sphaeroides HY01 under tetracycline stress showed clear enhancement on H₂ production performance of the recombinant strain pRK415/HY01. The maximum H₂ production rate of pRK415/HY01 was enhanced by 10%–70% compared with the control group in the absent of Tc. Supplementing with Tc, the wild type strain HY01 showed repressed cell growth and reduced H₂ production performance. The tetAR genes knockout test demonstrated that the expression of tetAR genes on pRK415 promoted the H₂ production performance. And within tolerance concentration (Tc < 2.5 mg/L), higher Tc concentration led to higher H₂ production performance of pRK415/HY01. Expression of tetAR genes in the genome of R.sphaeroides HY01 by substituting partial of hupSL genes enhanced the H₂ production performance as well. The mechanism of the H₂ production performance enhancement was discussed.