压气机机匣零件切削刀具配置专家系统开发

现代航空发动机零件结构越来越复杂,涉及的刀具种类与数量也越来越多,给刀具选择与工艺制定带来了严峻挑战.以某型压气机机匣零件为研究对象,以最佳刀具配置为研究目标,在压气机机匣零件切削数据库的基础上,设计开发了基于B/S结构的压气机机匣零件切削刀具配置专家系统,并进行了实例演示.该系统首先根据被加工对象特征及其需求,运用规则推理方法初选刀具;进而应用人工神经网络预测初选刀具的耐用度及被加工特征的表面粗糙度;最后以该预测结果作为参考,应用综合评判技术进行刀具性能评价,并对所选刀具进行优化排序和完成推荐.系统运行实例验证了所开发系统能够实现压气机机匣零件切削加工刀具的智能选取.     

熔盐泵外特性及内部流动的试验及数值模拟

为了揭示熔盐泵内两相流动的规律,研究了熔盐泵试验方法,得到了熔盐泵的外特性.采用粒子成像测速（PIV）技术测量了蜗舌附近熔盐泵内流动,并对熔盐泵内两相流动进行了非定常数值模拟,阐述了试验结果与模拟结果之间的差别,获得了晶体颗粒在熔盐泵内的体积分数分布,并分析了其演化规律.结果表明:熔盐泵内晶体颗粒体积分数分布较稳定,颗粒集中于叶片吸力面附近.粒径对颗粒在叶轮流道内的积聚影响比较大,粒径越大,颗粒积聚越明显.熔盐泵出口静压周期性波动,波动幅度受叶轮内颗粒体积分数分布影响.      

Ground experimental investigations into an ejected spray cooling system for space closed-loop application

Spray cooling has proved its superior heat transfer performance in removing high heat flux for ground applications.However,the dissipation of vapor–liquid mixture from the heat surface and the closed-loop circulation of the coolant are two challenges in reduced or zero gravity space environments.In this paper,an ejected spray cooling system for space closed-loop application was proposed and the negative pressure in the ejected condenser chamber was applied to sucking the two-phase mixture from the spray chamber.Its ground experimental setup was built and experimental investigations on the smooth circle heat surface with a diameter of 5 mm were conducted with distilled water as the coolant spraying from a nozzle of 0.51 mm orifice diameter at the inlet temperatures of 69.2 °C and 78.2 °C under the conditions of heat flux ranging from 69.76 W/cm~2 to 311.45 W/cm~2,volume flow through the spray nozzle varying from 11.22 L/h to 15.76 L/h.Work performance of the spray nozzle and heat transfer performance of the spray cooling system were analyzed;results show that this ejected spray cooling system has a good heat transfer performance and provides valid foundation for space closed-loop application in the near future.     

Direct thrust test and asymmetric performance of porous ionic liquid electrospray thruster

In order to meet the demand of CubeSats for low power and high-performance micro-propulsion system, a porous ionic liquid electrospray thruster prototype is developed in this study. 10 × 10 conical emitter arrays are fabricated on an area of 3.24 cm² by computer numerical control machining technology. The propellant is 1-ethyl-3-methylimidazolium tetrafluoroborate. The overall dimension of the assembled prototype is 3 cm × 3 cm × 1 cm, with a total weight of about 15 g (with propellant). The performance of this prototype is tested under vacuum. The results show that it can work in the voltage range of ±2.0 kV to ±3.0 kV, and the maximum emission current and input power are about 355 μA and 1.12 W. Time of Flight (TOF) mass spectrometry results show that cationic monomers and dimers dominate the beam in positive mode, while a higher proportion of higher-order solvated ion clusters in negative mode. The maximum specific impulse is 2992 s in positive mode and 849 s in negative mode. The thrust is measured in two methods: one is calculated by TOF results and the other is directly measured by high-precision torsional thrust stand. The thrust (T) obtained by these two methods conforms to a certain scaling law with respect to the emission current (I_em) and the applied voltage (V_app), following the scale of T ∼ I_emV_app^0.5, and the thrust range is from 2.1 μN to 42.6 μN. Many thruster performance parameters are significantly different in positive and negative modes. We speculate that due to the higher solvation energy of the anion, more solvated ion clusters are formed rather than pure ions under the same electric field. It may help to improve thruster performance if porous materials with smaller pore sizes are used as reservoirs. Although there are still many problems, most of the performance parameters of ILET-3 are good, which can theoretically meet the requirements of CubeSats for micro-propulsion system.     

考夫曼离子推力器放电室数值模拟研究综述及展望

首先分析了影响考夫曼离子推力器放电性能的关键因素,然后按照仿真模型的维度对考夫曼离子推力器放电室数值模拟方法进行了分类综述和优缺点分析,并针对以流体方法为基础的各向异性界面问题进行了分析。在此基础上,概述了零维模型、二维模型和三维模型下针对放电室所取得的数值模拟研究结果。最后对考夫曼离子推力器放电室数值模拟研究进行了总结及展望。     

出口宽高比对双涵道S弯喷管流动特性的影响

为了明晰出口宽高比对基于真实排气混合器构型的S弯喷管流动特性的影响机制,数值模拟了不同出口宽高比下的双S弯喷管内/外流特性。结果表明：出口宽高比对排气混合器附近的流场特征影响较小,但增加出口宽高比导致喷管下游纵向转弯处的涡量减小,而涡的横向运动更加剧烈,由此带来的涡损失及内/外涵掺混损失沿纵向有所减小,沿横向持续增大。随着出口宽高比的增加,纵向两弯处及等直段区域的壁面剪切应力减小,相应的摩擦损失和局部损失降低;而上、下壁面极限流线的扩张-汇聚程度增强使得该区域的摩擦损失增大。宽高比的增加导致喷管出口附近气流的轴向速度逐渐增大,出口下游的尾喷流速度核心区长度逐渐缩短。不同出口宽高比条件下,喷管几何构型与排气混合器相互作用产生的多种流动损失的变化趋势相反,综合起来对S弯喷管的气动性能影响较小。     

典型航空电连接器接触件动态性能仿真分析

通过有限元仿真分析,确定电连接器接触件在受到外部振动、冲击载荷和温度载荷作用下的响应。在对接触件合理简化的基础上建立了静力学模型、基于 Hertz理论的接触力学模型和振动力学模型。建立了接触件有限元仿真模型,通过插拔分析、模态分析、谐响应分析、随机振动分析和热-结构耦合分析,确定了不同载荷和工况下的接触状态、变形、应力和轴向滑移量。结果表明,接触件的固有频率较高,在正常工况下不会发生共振问题,但接触界面在振动和高温作用下可发生微米级的相对滑移,而且振动载荷对径向变形的影响要高于轴向变形,温差作用下的滑移量比振动条件下更大。     

一种姿态控制发动机点火装置简介

介绍一种姿态控制发动机点火装置，它由一对桩带式电发火管组成，对发动机实施尾部点火，具有防静电，防射频，防核辐射能力，能够在γ射线剂量率１０＾６Ｂｙ／ｓ的状态下实现１Ｗ，５ｍｉｎ不发火。它体积小，重量轻，价格低廉，该装置应用于姿态控制发动机表现出较高的可靠和于姿态控制或战术型号发动机。     

质子交换膜燃料电池膜电极组件性能分析

对由亲水电极与Nafion 112质子交换膜制备的质子交换膜燃料电池(PEMFC)膜电极组件(MEA),测试了工作温度、气体压力、气体相对湿度和气体流量等对MEA性能的影响。试验和分析显示MEA的适宜工作条件为:温度70℃、压力0.2~0.3 MPa、H2/O2或空气的相对湿度为100%/60%、H2/O2或空气流量计量比分别为1.1~1.2/1.2~1.5或2.0~2.5。在此条件下对MEA进行了1000 h放电性能测试。结果表明,该MEA的结构和性能稳定,能满足燃料电池长寿命工作要求。     

基于半实物／数字仿真的相控阵雷达抗干扰性能评估

研究了基于半实物/数字仿真的相控阵雷达系统抗干扰性能评估问题。首先分析了仿真与评估系统整体构成,然后讨论了数据录取的要求,以及数据预处理的关键环节。针对各种复杂的电子战战情给出了探测航迹与目标真实轨迹配对的双门限方法。最后针对相控阵雷达对抗的整体过程,建立了评估指标体系,并且给出了评估实例。