高速开关阀在起落架半主动控制中的应用研究(英文)

To select or develop an appropriate actuator is one of the key and difficult issues in the study of semi-active controlled landing gear. Performance of the actuator may directly affect the effectiveness of semi-active control. In this article, parallel high-speed solenoid valves are chosen to be the actuators for the semi-active controlled landing gear and being studied. A nonlinear high-speed solenoid valve model is developed with the consideration of magnetic saturation characteristics and verified by test. According to the design rule of keeping the peak load as small as possible while absorbing the specified shock energy, a fuzzy PD control rule is designed. By the rule controller parameters can be self-regulated. The simulation results indicate that the semi-active control based on high-speed solenoid valve can effectively improve the control performance and reduce impact load during landing.     

带芯子的碳—碳端头烧蚀外形计算

对电弧加热器试验条件下端头的烧蚀外形进行了数值仿真，考察了碳－碳端头烧蚀外形随来流条件的变化规律，重点研究了将碳－碳端头体轴附近材料换成由另一种烧蚀速度较快的材料制成的芯子后的匹配烧蚀问题，揭示芯子对烧蚀外形的影响规律。     

Cleaning space debris with a space-based laser system

High-energy pulsed laser radiation may be the most feasible means to mitigate the threat of collision of a space station or other valuable space assets with orbital debris in the size range of 1–10 cm. Under laser irradiation, part of the debris material is ablated and provides an impulse to the debris particle. Proper direction of the impulse vector either deflects the object trajectory or forces the debris on a trajectory through the upper atmosphere, where it burns up. Most research concentrates on ground-based laser systems but pays little attention to space-based laser systems.There are drawbacks of a ground-based laser system in cleaning space debris. Therefore the placement of a laser system in space is proposed and investigated. Under assumed conditions,the elimination process of space debris is analyzed. Several factors such as laser repetition frequency, relative movement between the laser and debris, and inclination of debris particles which may exercise influence to the elimination effects are discussed. A project of a space-based laser system is proposed according to the numerical results of a computer study. The proposed laser system can eliminate debris of 1–10 cm and succeed in protecting a space station.     

气体压力对钛合金电火花诱导烧蚀加工的影响

氧气在电火花(EDM)诱导烧蚀加工过程中起到参与氧化放热、蚀除金属和冷却的作用。以气体压力为研究对象,通过理论推导,证明增加气体压力可提高气体流速、减小气体分子平均自由程、提高氧化扩散速度和气体蚀除力以及加速能量散失。通过测得不同气体压力下的击穿电压、击穿延时和工作电压,试验证实了气体压力对击穿电压和击穿延时有较大影响;通过建立EDM诱导烧蚀加工放电等效模型,表明工作电压变化是由电极和工件表面氧化引起的。研究了气体压力对EDM诱导烧蚀加工材料蚀除率(MRR)、相对电极损耗(REWR)和表面粗糙度的影响。结果表明:随着气体压力增大,材料蚀除率先增加后降低,电极相对损耗缓慢减小,表面粗糙度显著降低。     

超声检漏方法及应用研究

超声检漏法是一种新型可快速定位漏点的无损检测方法。文章对泄漏超声进行了理论分析,说明了方向角、检测距离等信号检出影响因素,建立了真空系统泄漏CFD模型,进行参数计算,并进行了真空系统泄漏超声检测试验和阀门内漏超声检测试验,总结出超声检漏试验方法,并初步得到声信号与泄漏量间的函数关系。     

液氧煤油发动机蒸发器路单向阀结构优化

在某次液氧煤油发动机试车中,由于蒸发器路单向阀调整流量小于设计流量,导致单向阀阀芯发生颤振,从而在发生器氧系统引入激励源,引起发生器供应系统的耦合振荡,发动机结构振动大幅增加,导致试车中止。根据发动机使用要求,对单向阀结构进行了结构优化。通过AMEsim软件对优化后单向阀进行的仿真分析及试验验证,表明优化措施有效。优化后单向阀参加发动机热试考核,工作正常。     

预分散酚醛中空微球对三元乙丙橡胶绝热层性能的影响及梯度化绝热层的研究

分别制备了预分散酚醛中空微球填充三元乙丙橡胶绝热层和梯度化三元乙丙橡胶绝热层,旨在开发低密度的新型高性能绝热材料。扫描电镜观察表明,预分散酚醛中空微球能完好、均匀地分散于三元乙丙橡胶基体中。由于酚醛中空微球具有很低的粒子密度和高的热阻性能,随预分散酚醛中空微球含量的增加,绝热层的密度、热导率和热扩散率显著降低,同时绝热层的比热容明显增大,表现出优异的绝热性能。与芳砜纶浆粕填充三元乙丙橡胶绝热层、酚醛中空微球填充三元乙丙橡胶绝热层相比,梯度化三元乙丙橡胶绝热层具有优异的绝热性能和耐烧蚀性能,同时又具有很低的密度,将在火箭发动机上具有广阔的应用前景。     

冷挤压成型在阀芯生产中的应用

从工艺方案和模具设计原则等方面探讨了冷挤压工艺应用于阀芯生产的原理与优势,介绍了一种典型阀芯的冷挤压工艺试验结果。试验证明采用冷挤压成型工艺能够解决影响阀芯密封性和产品质量稳定性的塑料与金属脱离等问题。     

悬空衔铁式电磁阀中S形簧片的研制

介绍了一种悬空衔铁式电磁阀用S形簧片的研制,该簧片用于航天器推进系统150 N发动机电磁阀。簧片研制的目标是高寿命、高可靠性和稳定性。根据要求设计生产了工程样机,在研制过程中对簧片的设计,仿真,工艺制造和试验方法进行了探索,并得到了较好的结果,通过了鉴定试验,即将进入工程应用阶段研制。     

PWM高速开关阀动态调节特性仿真研究

针对某型号发动机燃油调节器的脉宽调制(PWM)高速开关阀,通过建立高速开关阀系统动态数学模型,开展了高速开关阀调节工作过程动态压力与流量特性的仿真研究。对影响开关阀动态输出特性的相关因素进行了比较分析,结果表明:阀座通径、驱动频率与容腔体积等是影响高速开关阀动态性能的主要因素,并提出相应的改进措施。为改善高速开关阀动态调节特性、提高作动控制系统的控制精度与性能提供参考与借鉴。