CFRP加固砌体填充墙抗燃气爆炸泄爆荷载的优化设计及动力响应

CFRP条带已广泛应用于结构构件的外贴抗爆加固.为了进一步提高砌体填充墙在泄爆荷载作用下的抗爆性能,同时控制加固材料成本,基于Hyperworks中的Opti Struct平台对典型砌体填充墙的CFRP外贴抗爆加固方案进行了拓扑优化,提出了一套优化加固方案.基于优化方案,建立了CFRP外贴加固砌体填充墙的精细化数值分析模型,模型的可靠性得到了试验结果的验证.基于数值模型,进一步讨论了燃气爆炸泄爆荷载作用下不同加固方式对单向和双向填充墙体动力响应和破坏模式的影响.结果表明,相较于传统方案,CFRP优化加固方案能显著提高砌体填充墙的抗爆能力;优化加固的单向墙呈窄X型破坏形式,优化加固的双向墙发生了边界剪切破坏.

小型压力容器微量泄漏检测技术与装置的研究

日常生产、生活中的小型压力容器因设计缺陷、外力持续作用等因素会出现容器内物质泄漏,从而对环境、生命安全构成威胁,特别是微量泄漏因其表象不显著易被忽略,封闭空间内的长期微量泄漏同样会因有毒、可燃气体体积分数增加而引发安全事故。以最常见的丙、丁烷混合气打火机为研究对象,设计了打火机微量泄漏检测仪,在可燃气传感器输出阻抗与泄漏体积分数函数关系的基础上,研究燃气微量泄漏模型和双重检测算法,通过特征匹配方式实现批量打火机中泄漏单体的快速定位和泄漏量的精确测量。实验结果表明:打火机燃气微量泄漏的检测效率高,漏检率小于0.01%,该技术同样适用于其他各类小型压力容器的微量泄漏检测。

CFD simulation of spontaneous coal combustion in irregular patterns of goaf with multiple points of leaking air

Based on the non-linear air leakage seepage equation for an anisotropic porous medium, on the seepage diffusion equation of multicomponent gas and on the seepage synthetic heat transfer equation of a porous medium, the numerical model for field flow problems of irregular patterns of a goaf with multiple points of leaking air is established and simultaneously solved by the upwind mode finite element method (G3 computer program). According to the complexity of irregular patterns of a goaf with multiple points of leaking air, the flow pattern in a large area of such a goaf and the variation in gases of methane, oxygen and CO and in temperature are theoretically described. In the calculation, the goaf is regarded as a caving anisotropic medium and the coupling effect of methane effusion on spontaneous combustion is considered. The simulation results agree well with practical experience. In addition, the spontaneous combustion process is also simulated, indicating that 1) the spontaneous combustion often takes place near the area where fresh air leaks in and 2) the fire sources can be classified into static and dynamic zones. Therefore, in practical fire preventing and extinguishing, we should clearly distinguish the upstream air leaking points from the downstream ones in order to take proper measures for leakage stopping.

Using acoustic technique to detect leakage in city gas pipelines

For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.

Design of hydrogen leakage detection and alarm processing system for the fuel cell power train lab

The hydrogen leakage detection and alarm processing system is established for the fuel cell （FC） power train lab to meet the hydrogen safety demand of the FC performance test and examination for the project named ＂Research and Development of the Vehicular Technology for the Fuel Cell City Bus＂ by Tsinghua University. The established hydrogen safety system includes the hydrogen supply system, hydrogen leakage detection system, alarm processing system, ventilation system, measures against electrostatic, thunder-arresting and explosion-protection, and the strict hydrogen operation rules. In this safety system, the explosion proof catalytic combustion sensors are used to detect the hydrogen leakage and the electrical control system is designed to process the alarm automatically. The hydrogen safety system plays an important role in the performance, examination of the FC and the assuring the personnel＇ s safety of the fuel cell power train lab.

为燃气管道“减压”——长春市东盛街道下大力气整治燃气管线安全隐患

4月14日,随着长春市二道区东盛街道长江花园小区最后一处违章占压燃气管线建筑物和堆放物清理拆除完毕,至此,涉及到这个街道的16处违章占压燃气管线隐患已全部清除。东盛街道被称为二道区的"首都",随着城市建设脚步加快,违章占压燃气管线的情况越来越多。辖区内一些单位和居民无视燃气管道使用安全规定,擅自在燃气管线上和周围搭建违章建筑,这一方面影响燃气公司对设施的正常巡检;另一方面,违章占压燃气设施。

Hydrogen FBG Sensor Using Pd/Ag Film With Application in Propulsion System Fuel Tank Model of Aerospace Vehicle

The high efficiency hydrogen fiber Bragg grating （FBG） sensor is presented. The sensitive film was a new alliance of palladium-silver （Pd-Ag）. In addition, the titanium （Ti） layer was used as the adhesive layer. The presented sensor showed the resolution of more than 60pm/1%H2, and a fast response time of4s - 5s was guaranteed in the 0.1%H2 - 4%H2 range. Moreover, the life time of the sensor was investigated. The obtained results showed that the sensor had an enhanced life time. Furthermore, the sensor was applied in the propulsion system fuel tank model of the aerospace vehicle. The obtained results indicated that it is a prevention system against the disaster aerospace due to hydrogen leakage.