冲击矿压的层裂板模型及实验研究

片帮型冲击矿压是煤壁局部失稳, 与煤壁层裂板结构的形成有关。分析了煤壁层裂板结构形成及压曲失稳破坏规律, 给出了裂纹扩展、贯通的应力判据以及随后形成的层裂板结构压曲失稳的条件, 并据此对冲击矿压进行模拟试验研究, 实验结果与理论分析基本一致。     

球扁壳结构计算的一种简化方法

本文提出一种球形扁壳结构计算的简化方法。利用变形的步进求和将结构计算的偏微分方程化为三次代数方程,从而获得球扁壳结构内力的精确简化表达式。并用算例说明这一方法的优点。     

Numerical simulation of flow instabilities in high speed multistage compressors

INTRODUCTIONTheusefuloperatingrangeofturbomachinerycompressionsystemsislimitedbytheonsetoffluiddynamicinstabilities.Bothformsofinstabilities,rotatingstallandsurge,willdegradecompressionsystemperformanceanddurabilityll].naditionally,thisundesirablebeh...     

前处理一步法工艺要素

结合工厂中的实际生产条件,对棉织物前处理一步法工艺中轧余率、温度、稳定剂,洗涤等工艺条件进行了论述,并讨论了影响一步法半制品质量的各项因素。     

基于数学形态学的矿区大规模滑坡堆积体失稳概率仿真分析

研究基于数学形态学的矿区大规模滑坡堆积体失稳概率仿真分析方法,为合理治理与预防堆积体滑坡事件提供科学依据。采集研究矿区大规模滑坡现场图像并绘制其堆积体剖面图,应用数学形态学提取出地形、骨架及边界等特征,通过ANSYS栅格生成堆积体失稳概率仿真计算模型,结合蒙特卡罗模拟法,仿真运算降雨因素影响下堆积体的失稳概率。结果表明,当降雨事件重现期增长时,滑坡堆积体的安全系数降低,其失稳概率升高;堆积体日失稳概率变化趋势与矿区的日降雨量趋势较为接近,失稳概率最高日与矿区实际发生堆积体滑坡事件的日期吻合,仿真分析结果可靠,可有效预防降雨导致的堆积体失稳灾害提供科学依据。     

传统街区改造中的"渐进更新"策略与低成本建造技术--以"重庆川道拐"街区为例

通过4年多的"渐进更新"和低成本的旧建筑再利用,一个典型的传统山地街区在延续原有城市肌理同时创造了新的城市景观和就业岗位.街区的更新模式与建筑策略有别于普遍的"大拆大建"做法,是旧城改造新模式的探索.文中强调渐进更新和旧建筑再利用是"政府引导"、"群众动员"与"规划设计"共同作用的良性结果,并分析了规划设计与实践的方法、手段、取得的成果与存在的问题.街区今天依然处于持续更新之中.     

无醛装饰纸贴面豆胶胶合板的工艺研究

目的为了解决装饰纸贴面人造板的游离甲醛问题,探究无醛装饰纸贴面胶合板的优化工艺和贴面后涂饰水性聚氨酯的表面耐磨性能。方法采用无醛豆胶为胶黏剂制备装饰纸贴面豆胶胶合板,并在其表面涂饰无醛水性聚氨酯涂料的方法。按照相关国标,检测和分析不同工艺参数对无醛装饰纸贴面豆胶胶合板的表面胶合强度以及不同水性聚氨酯涂料涂饰量对耐磨性能的影响。结果在实验区间内,当无醛豆胶的单面施胶量为200 g/m2,热压温度为150℃,热压时间为1.5 min,热压压力为1 MPa时,无醛装饰纸贴面豆胶胶合板的表面胶合强度最高;当无醛水性聚氨酯涂料的表面涂饰量为190 g/m2时,无醛装饰纸贴面豆胶胶合板的表面耐磨性能最佳。结论采用无醛豆胶为胶黏剂制备胶合板时,无醛豆胶具有较好的渗透性能,无醛水性聚氨酯涂料具有良好的表面性能。     

Recent progress of nuclear liquid gas phase transition

Recent progress on nuclear liquid gas phase transition (LGPT) has been reviewed, especially for the signals of LGPT in heavy ion collisions. These signals include the power-law charge distribution, cluster emission rate, nuclear Zipf law, bimodality, the largest fluctuation of the fragments, A -scaling, caloric curve, phase coexistence diagram, critical temperature, critical exponent analysis, negative specific heat capacity and spinodal instability etc. The systematic works of the authors on experimental and theoretical LGPT are also introduced.     

非对称通道内亲疏水结构影响下的纳米气泡滑移效应

目的 研究非对称性通道中亲疏水表面结构影响下纳米气泡特征与边界滑移之间的关系,以实现良好的流体减阻效果.方法 采用二元体系分子动力学方法,研究纳米气泡在通道流动中产生的滑移减阻效应.首先建立上下壁面非对称微通道模型,通过考虑微通道流动传热过程,探究纳米气泡影响下的微通道界面速度滑移现象.结果 保持亲水下壁面高度以及上下...     

Experimental Study on Inducement and Development of Flow Instabilities in a Centrifugal Compressor with Different Diffuser Types

A centrifugal compressor is a typical compressed air energy storage device. In order to ensure the safety of the compressed energy storage process in the compressor, the internal unsteady flow phenomena need to be closely monitored, especially some serious ones like stall and surge. It is necessary to explore the mechanism of flow instabilities under different conditions. A centrifugal air compressor was tested with a vaneless diffuser and a variable vaned diffuser with five different vane setting angles, respectively. Various diffuser types resulted in various modes of flow instabilities prior to surge. The vaneless region between the impeller and the diffuser was focused on. Multiple high-speed sensors were arranged along the circumferential direction. The pressure signals at all these positions were being measured and collected in real time as the compressor was slowly throttled into surge. This paper emphasizes on the influence of matching between the impeller and the diffuser on the flow instability. The experimental results showed that the diffuser vane setting angle affected the stall characteristics. Due to the asymmetry of the volute, the circumferential pressure distribution was always severely distorted prior to surge. A high-pressure region appeared near the volute tongue, and a low-pressure region was formed away from the volute tongue. In the case of the vaned diffuser with non-design installation angle and the vaneless diffuser, the rotating stall signal was originated in the low-pressure region and propagated circumferentially. However, in the case of the vaned diffuser with the design installation angle, the circumferential high-pressure region became the most sensitive region for the generation of stall, and another form of instability occurred there. Both the inducement and development of these flow instabilities have been studied. The dynamic experimental research on the compressor matching different types of diffusers could be a good case supplement.