浮动壁火焰筒壁温试验和计算分析

对某浮动壁火焰筒的壁温进行了试验和计算分析。该火焰筒应用了新型的浮动壁结构和高效的冲击/发散复合冷却技术。壁温分布试验在全环形燃烧室试验台上进行,采用热电偶和示温漆测量。计算采用了稳态导热问题的有限元求解方法。研究分析表明,火焰筒壁温在材料的长期许用温度范围内,壁温计算反映了火焰筒壁温的分布规律和趋势。冲击/发散复合冷却方式的轴向壁温梯度小于缝槽气膜冷却方式,对降低热应力水平,延长火焰筒使用寿命有利。     

激波管中测量JP-10点火延时的吸附问题研究

在JP-10点火延时的激波管实验中,JP-10在激波管壁的吸附导致气相浓度的不确定是测量结果分散的主要原因之一.利用精确测定的吸附曲线确定了实验时JP-10真实的气相浓度,解决了高碳数碳氢燃料点火延时激波管实验时管壁吸附影响燃料气相浓度确定的困难.实验显示JP-10的吸附符合Langmuir吸附等温关系.     

脉动压力测量技术在火箭发动机试验中的应用

为研究和探索火箭发动机地面试验推力室脉动压力测量方法和数据分析技术,介绍了火箭发动机试验中脉动压力测量系统的组成和参数的测量方法;分析了引压导管的动态特性及其对脉动压力参数测量的影响;采用齐平安装的方式,按照所述方法建立脉动压力参数测量系统;结合推力室多个振动测点的数据,分别采用快速傅里叶变换(FFT)和小波包分解两种...     

Influence of deformation zone length on bending radius of SS304 tubes with small diameters manufactured via free bending-based active motion

In three and six-axis free-bending equipment, the deformation zone length(A) is a fixed mechanical structure parameter modified when the relevant structure is redesigned and manufactured. In this study, a six degree of freedom(6-DOF) parallel mechanism was used as the control mechanism of the bending die, and a new method of changing the deformation zone length(A)was proposed. Firstly, an idealized geometric model of free bending-based active motion was established. Then, the influence of the de...     

Plastic wrinkling model and characteristics of shear enforced Ti-alloy thin-walled tubes under combination die constraints and differential temperature fields

Plastic wrinkling predictions and shear enforced wrinkling characteristics of Ti-alloy thin-walled tubes under combination die constraints have become key problems urgently in need of solutions in order to improve forming quality in their shear bending processes under differential temperature fields. To address this, a wrinkling wave function was developed by considering their shear bend deformation characteristics. Based on this wave function and the thin shell theory, an energy prediction model for this type of wrinkling was established. This model enables considera-tion of the effects of shear deformation zone ranges, material parameters, loading modes, and fric-tion coefficients between tube and dies on the minimum wrinkling energy. Tube wrinkling sensitive zones (WSZs) can be revealed by combining this wrinkling prediction model with a thermal-mechanical coupled finite element model for simulating these bending processes. The reliability of this wrinkling prediction model was verified, and an investigation into the tube wrinkling char-acteristics was carried out based on the experimental conditions. This found that the WSZs are located on either a single side or both sides of the maximum shear stress zone. When the friction coefficients between the tube and the various dies coincide, the WSZs are located on both sides. The larger the value of the tube inner corner radius and/or the smaller the value of the outer corner radius, the smaller the wrinkling probability. With an increase in the value of the moving die dis-placement, the wrinkling probability increases at first, and then decreases.     

电视导引头图像闪烁故障分析

针对电视导引头存在的“图像闪烁”故障，重点分析了故障的常发生部位，如硅靶管、CCD、图像处理电路和电视摄像机光圈等，并从故障部位的结构特点和工作原理入手，详细阐述了故障产生的原因、机理以及排故方法，为同类故障的修理提供参考。     

挤压式无扩口导管密封性能改进研究

针对某型飞机在使用过程中出现的气动系统严重漏气、液压系统低压渗油等问题,对导管加工工艺、鉴定试验及装配工艺进行改进与优化,降低了导管故障率,提高了装备使用可靠性。     

冲击波对工程结构及装备的动载试验研究

获得国家科学技术进步一等奖的“1485抗爆激波管”是用来模拟爆炸冲击波的室内试验设备，其驱动段是以燃烧火药为能源，锥管前面管体内径是348mm，锥管后面试验段及其出口段内径为1485mm。试验段内部超压可达0．05～1．20MPa。地上试验段参试物安装在管内。地下试验段是内径2．50m、高3．00m的箱体，内部可进行地下结构模型试验。驱动段膜片夹紧力是由8个油缸及其二级连杆增力机构来完成。有长江三峡大坝动力响应试验、地下隧道试验、地形对冲击波影响试验及人防工事试验等已做过的部分典型试验。     

Temperature effect on buckling properties of ultra-thin-walled lenticular collapsible composite tube subjected to axial compression

This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube(LCCT) subjected to axial compression.The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element(FE) model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.     

Fronts and thermohaline structure of the Brazil–Malvinas Confluence System

Fronts and thermohaline structure of the Brazil–Malvinas Confluence System (BMCS) are studied from climatic data, “Marathon Exp. Leg.8, 1984” data, and Sea surface temperature (SST) data base “ds277-Reynolds” (1981–2000). The South Atlantic Central Water (SACW) is divided in two main types: tropical (TW) and subtropical water (ST). Water masses, Fronts, Inter-Frontal and Frontal Zones are analysed and classified: (a) the water masses: Tropical Low-Salinity Water, Tropical Surface Water, Tropical Tropospheric Water, Subtropical Low-Salinity Water, Subtropical Surface Water, Subtropical Tropospheric Water. T,S characteristics of intermediate, deep and bottom water defined by different authors are confirmed and completed; (b) the Inter-Frontal Zones: Tropical/Brazil Current Zone, Subtropical Zone and Subantarctic Zone; (c) the Frontal Zones: Subtropical, Subantarctic and Polar, and (d) the Fronts: Subtropical Front of the Brazil Current, Principal Subtropical Front, North Subtropical Front, Subtropical Surface Front, South Subtropical Front, Subantarctic Surface Front, Subantarctic Front and Polar Front. Several stable T–S relationships are found below the friction layer and at the Fronts. The maximum gradient of the oceanographic characteristics occurs at the Brazil Current Front, which can be any of the subtropical Fronts, depending on season. Minimum mean depth of the pycnocline coincides with the Fronts of the BMCS, indicating the paths of low-salinity shelf waters into the open ocean. In the work it is shown how to recover the horizontal and vertical thermohaline structure of waters from satellite data RSMAS SST.