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.     

丙烯酸装置循环气压缩机叶片损伤分析与修复

某石化公司丙烯酸装置循环气压缩机在运行过程中,一级叶片突然发生断裂,导致机组停机。采用宏观检查、扫描电子显微镜、能谱分析等方法对断裂叶片进行检验和检测,将断裂叶片的材质、裂纹及断口特征检测结果与疲劳断裂特征和机组运行状况进行对比,确定压缩机叶片的断裂系其达到疲劳寿命所致,提出采用激光熔覆方法对压缩机叶片进行修复,介绍了修复工艺操作程序要点,可为同类故事的处理提供参考。     

空压机润滑油系统可靠性试验研究

对空压机润滑系统进行分析,提出了一种润滑油压力调节机构,保证了空压机在高油温时油压正常,为空压机运动件提供充分润滑,从而提高空压机运行的可靠性。实验证明了该机构是可靠的,为空压机润滑系统设计提供了参考依据。     

来流马赫数影响高负荷扇形扩压叶栅气动性能的研究

为研究亚音速高负荷扇形扩压叶栅NACA0065-K48的变工况性能,采用数值方法研究了来流马赫数对叶栅气动性能和流场结构的影响,来流马赫数的取值范围为0.3～0.8。计算结果表明:随着来流马赫数的增大,叶栅静压比不断提高,但总压损失先减后增,马赫数在0.5～0.7范围内叶栅具有较好的综合气动性能。扇形叶栅下角区分离程度大于上角区的不平衡流动现象会随着马赫数的增大而加剧,通道涡则是这一发展趋势的主导,且马赫数达到0.7之后,下角区通道涡与集中脱落涡趋于融合。此外,下端壁分离螺旋点的形成与发展是控制下角区分离程度和损失大小的关键。     

旋转式采煤工艺在煤矿生产中的应用

采煤工艺作为煤矿正常生产的核心,直接关系到综采作业的效率、煤炭回采率和综采作业的安全性,随着对综采作业要求的不断提高,旋转式采煤工艺在煤矿井下的应用范围也不断扩大。以黄家沟煤业1205综采作业面为分析对象,对旋转式采煤工艺在井下的应用情况进行了研究,为优化综采方法、提升综采作业效率和煤炭回采率奠定基础。     

实用型气动旋转装夹工作台的设计

该设计实例为一种气动旋转装夹工作台,详细介绍该装置的设计思路,分析其结构和动作原理。该装置在实际应用中,完全满足了特殊工况需求,性能稳定,具有一定的推广价值。     

入口长度对旋转直通式迷宫气封流场及流场力的影响

迷宫密封的转子和定子部件之间的流场和流场力直接影响转子的振动和稳定性。为了深入了解迷宫密封的流场和流场力特性,选取旋转直通式迷宫气封为研究对象,利用稳态CFD分析方法,研究密封入口长度对旋转直通式迷宫气封泄漏、流场和流场力的影响。考虑和不考虑入口预旋的影响,计算不同入口长度的旋转直通式迷宫气封的泄漏量、流场速度流线、总压强分布、流体压力和流体黏滞力。结果表明:随着入口长度的增大,密封流场泄漏量先增加后减小,转子表面流体压力和流体黏滞力先增加后快速减小;入口长度影响着直通式迷宫气封流场力,存在一个特定的入口长度,使转子表面的流体压力和流体黏滞力最大;当考虑入口预旋时,泄漏量、流体压力和流体黏滞力均有所减小。     

汽车密封件双料一体旋转模具设计

针对PP+TPE汽车密封件设计了大型双料一体旋转注射模,介绍了二次合模的精确定位、可控注射系统、顶出平衡设计。该模具技术能够使两种性能完全不同的材料按照指定区域分布,并且达到塑件尺寸的精度需求,实现同时与钣金、玻璃、塑件等不同材质的零件进行复合配套。本项目实施后,在模具精度、寿命等方面接近或部分达到国外同类产品先进水平,而价格仅为国外产品的40%,性价比优势明显。     

Study on the friction interface evolution during rotary friction welding of tube

In this study, evolution characteristics of the friction interface during rotary friction welding of tube were investigated. The friction interface that obtained at different welding stage were observed by confocal laser scanning microscopy. The results show that the friction interface transforms from sliding friction state to visco-plastic deformation state when the welding torque reaches the peak value. In addition, based on the thermodynamic framework extracted from the maximum entropy production principle, an analytical model for transition criterion from sliding friction to visco-plastic deformation was established. The model was verified by the corresponding experimental results of eight alloys, which indicated that the accuracy and generality of the model is satisfactory.     

转底炉处理赤泥工艺技术

为了综合利用氧化铝冶炼产生的赤泥，探索在转底炉中直接还原赤泥、磨矿磁选获得高品位直接还原铁。通过实验室试验摸索了转底炉还原工艺参数，并在转底炉工业试验线进行了工业试验。实验室结果表明，赤泥还原后的直接还原铁(DRI)金属化率可达88.6%，磁选后的铁品位可达82.1%，磁选后的铁回收率可达88.9%。工业试验中，转底炉还原后，产品金属化率平均为69.2%，将还原后的DRI磁选获得高品位的DRI产品，磁选后DRI的铁品位为72.8%，磁选后铁回收率达到了85.2%,初步打通了在转底炉中还原赤泥、磁选的工艺路径。