超低比转速离心泵内流场计算及分析

运用FLUENT流体计算软件及GAMBIT前处理软件,采用三维k-ε双模型方程计算了一台高速超低比转速离心泵的内部流场。计算区域为从诱导轮进口到蜗壳出口的整个流场,通过计算得到了泵内流场的流动规律,并结合传统的泵水力估算方法,估算了泵的扬程、轴功率及效率,最后对该高速超低比转速离心泵进行了水力验证试验。验证结果表明所采用的计算方法可行。     

液氢诱导轮内部流场数值研究

为有效地预测液氢诱导轮在额定工况下的工作性能,采用了有限体积差分格式、显式时间推进法和多重网络法求解清华大学热能工程系设计的液氢诱导轮内部三维不可压粘性流场。计算表明,该液氢泵设计合理,可以满足工程要求。     

载人飞船主动流体循环回路离心泵可靠性试验研究

文章通过对泵组件可靠性指标的分析 ,根据泵空间飞行的实际情况 ,进行了可靠性试验方法分析 ,描述了可靠性试验系统与试验结果 ,得出了飞船离心泵组件满足可靠性指标达到 0 999的结论。     

Impact of the thermal effect on the load-carrying capacity of a slipper pair for an aviation axial-piston pump

A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity. At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.     

Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

Based on the structure of a certain type of aviation axial-piston pump＇s valve plate which adopts a pre-pressurization fluid path （consisting a damping hole, a buffer chamber, and an orifice） to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This sin- gle-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The sin- gle- and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic （CFD）. The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and opti- mized design recommendations for the aviation axial-piston pump have been given out.     

燃烧场吸收光谱诊断技术研究进展

基于可调谐半导体激光吸收光谱（TDLAS）的视线测量技术,有能力实现流场温度、速度、组分浓度等参数的快速测量。作为一种有效的诊断工具,TDLAS传感器已经在燃烧和推进系统的研究和开发中获得广泛应用,为改善系统的性能发挥着越来越重要的作用。新应用机会的出现,对传感器提出新挑战的同时也促进了相关技术的进步。概括介绍了TDLAS技术的发展水平、在燃烧场诊断中的应用及未来的潜力,为相关研究人员提供参考。     

汽车单叶片真空泵设计中的最优椭圆曲线

单叶片真空泵的设计主要是确定泵体内腔曲面,使同时作旋转运动和径向滑动的叶片的圆柱形端面和它保持相切。泵体内腔曲面的投影必须是一条封闭的光滑曲线。设计时,这条光滑曲线的一部分通常被提前选定,而剩余部分则根据几何约束产生。尽管一般的椭圆曲线可以满足参考曲线和生成曲线在连接点一阶可导,但在连接点通常是二阶不连续的。将找出一条最优的椭圆参考曲线,使得泵腔形线在连接点处不仅是一阶连续的而且是二阶连续的。这将使得泵的运转更加平稳并减小由于叶片径向加速度不连续产生的振动和噪声。     

柱塞组合收口的方法及影响因素

柱塞组合收口是柱塞泵生产的关键制造技术,介绍了柱塞组合收口的3种主要方法及影响因素.     

双齿气体循环泵基本几何理论和容积计算

以数学几何理论为基础,通过坐标变换和包络条件推导了阴阳转子的基本型线方程,建立了双齿气体循环泵的数学模型。研究了阴阳转子相互啮合时啮合点位置随阴转子转角的变化关系。采用了线积分的计算方法推导出工作容积的基元面积随转角的变化关系,可简化工作容积的计算难度。结果表明:在转角为0和π的时候,阴阳转子会形成一个封闭的无效区域导致了工作腔的基元面积随转角变化过程中的突升和突降。在吸气结束时,由于吸气腔相较于排气腔多了一个与吸气口相连的部分导致了基元面积的突降。这些基本几何理论的建立可为双齿气体循环泵的应用打下一定的理论基础。     

基于雪崩二极管的太赫兹高次谐波混频器

文章介绍了一种基于雪崩二极管的太赫兹高次谐波混频器。雪崩击穿效应中的非线性特性能够引起高次谐波的频率变换效应。这种特性使雪崩二极管能够应用于毫米波及太赫兹频段的高次谐波混频。文章基于雪崩击穿效应中的非线性特性产生高次谐波的频率变换效应,提出将雪崩二极管应用于太赫兹频段的高次谐波混频,并从理论上分析高次谐波特性及其电路结构。16次谐波混频器获得了15dB的变频损耗,实验结果表明雪崩管高次谐波混频技术是一种极具应用价值的技术。