利用Tracker软件实现动量守恒定律的验证

利用Tracker软件具有的自动追踪功能,有效地跟踪气垫导轨上物体的运动,实时描绘出物体运动位移-时间曲线,利拟合出物体运动过程的动量-时间曲线,很好的验证了动量守恒定律。与传统的实验相比,数据处理过程简单,结果精确度也更高。     

钝感高能炸药爆轰产物JWL状态方程再研究

对钝感高能炸药JB-9014的爆轰产物JWL状态方程进行了深入研究。利用改进的圆筒试验技术,得到了筒壁膨胀的质点速度、位移和加速度的实验结果;通过解析分析和曲线拟合相结合的方法,确定了爆轰产物JWL状态方程参数;采用ANSYS/LS-DYNA3D程序进行了数值模拟,并与实验结果进行了对比和分析,验证了状态方程参数的适用性。     

利用狭缝扫描法测量超声波扩散角

利用狭缝扫描获得超声波束横截面上强度积分分布曲线,利用此积分曲线对应的微分曲线的半峰全宽计算得到超声波扩散角。此方法克服了小孔测量扩散角方法中信号微弱的弊端,提高了超声波扩散角测量精度。     

狭缝相机测量目标速度的精度分析

本文对狭缝相机测量目标速度的公式: 进行了分析;讨论了影响测量精度的因素。用XF—70狭缝摄影机对目标进行了多次拍摄,得到了翔实的实验数据,并对数据进行处理。根据(1)式计算的目标速度的标定值比较;用扫描摄影根据(2)计算的速度与自由落体运动的理论速度进行比较。     

不同起爆方式对含铝炸药水中爆炸近场冲击波压力的影响

 采用SJZ-30和GSJ-15型高速扫描相机,对端面点起爆、侧边点起爆和中心点起爆方式下,HLZY-1含铝炸药水中爆炸近场冲击波传播过程进行了实验观测,通过数字化方法得到了炸药近场冲击波沿狭缝方向的扫描曲线和冲击波压力变化曲线。研究表明,起爆方式对炸药水中爆炸初始冲击波峰值压力以及近场冲击波峰值压力的衰减有重要的影响。研究结果可以为水中兵器战斗部的设计以及毁伤效能评估提供参考。     

超高速转镜扫描相机扫描速度的校准及应用方法

研制了一套超高速转镜扫描相机扫描速度的校准装置，采用严格控制狭缝宽度和边缘质量的双狭缝、超快响应（0.7 ns）的光电倍增管以及相应措施,改善光电倍增管阴极不同部位灵敏度的一致性，使得校准装置的相对测量扩展不确定度达到了0.1％；给出了扫描速度校准的应用方法，并且分析了气压对相机符合转速的影响.     

校正时间畸变的光学镜头的设计与评价

由于变象管存在时间畸变,使萤光屏上的扫描象变弯。在皮秒变象管中曾采用球面阴极球面网暂时缓和了这一矛盾。但在飞秒技术中若继续延用上述方法,在变象管的制造工艺上是难以实现的。为此,我们设计了一个能校正时间畸变的狭缝成象镜头。即在入射狭缝后加入一个正场镜,使光阴极上高度为7mm的狭缝象的最大时间畸变为-3.5ps,从而达到了与变象管上正的时间畸变相抵消的目的。系统补偿时间畸变后其最大剩余量小于0.1ps。     

一种同步研究透明材料折射率和动力学特性的实验方法

基于电磁加载装置CQ-4,建立了一种同步开展透明材料折射率和高压声速测量的实验方法.完成了聚甲基丙烯酸甲酯(PMMA)窗口材料14 GPa斜波压缩实验,利用多点双光源外差位移干涉测速仪(dual laser heterodyne velocimetry, DLHV),获得了PMMA样品后表面的速度历史曲线.速度曲线表现出明显的双波结构,表明PMMA样品出现了弹塑性转变.通过实验数据处理,一发实验同步获取了PMMA的折射率-粒子速度光学特性和拉氏声速-粒子速度动力学特性.     

基于虚拟双差动共焦的快速表面轮廓测量方法

针对传统共焦显微技术定焦过程中扫描速度和扫描精度无法兼顾的问题,提出了一种基于虚拟双差动共焦的快速表面轮廓测量方法。其将传统共焦响应曲线向前平移和向后平移指定量得到虚拟前焦和虚拟后焦信号;然后将虚拟前、后焦信号与原始共焦信号分别相减,并将相减结果做相加处理得到虚拟双差动曲线。虚拟双差动曲线具有大线性范围、高定焦灵敏度的特点,在大扫描间距情况下获取表面轮廓时,可实现样品表面轮廓的快速、高精度的定焦。仿真分析及实验结果表明,与传统差动共焦显微成像方法相比,虚拟双差动共焦表面轮廓测量方法可在保持高定焦精度的前提下,将几何形貌成像速度提高2倍以上。     

用光纤光栅传感器研究压电陶瓷的特性

提出了一种利用光纤光栅传感器研究压电陶瓷特性的新方法.该方法采用非平衡Michelson扫描干涉仪对光纤光栅传感信号进行相位解调,通过观测波长漂移引起的相移,从而获得压电陶瓷的位移量与所加电压间的关系.实验分析了迟滞特性和蠕变现象,得到了压电陶瓷的电压-位移特性曲线以及蠕变特性曲线.实验表明,光源功率的波动对压电陶瓷迟...     

狭缝相机测量目标速度的精度分析

本文对狭缝相机测量目标速度的公式: V₀=(l/l′)V_F(1)V₀=tgφ·V_F/M(2)进行了分析;讨论了影响测量精度的因素。用X—70狭缝摄影机对目标进行了多次拍摄,得到了翔实的实验数据,并对数据进行了处理。根据(1)式计算的目标速度与速度的标定值作了比较;扫描拍摄时,根据(2)式计算的速度与自由落体运动的理论速度进行了比较。得出了XF—70狭缝相机作同步摄影时,其测量速度的相对精度达0.2%。用作扫描摄影时,其速度测量精度相对达0.8%的结论。     

An experimental investigation of dual-resonant and non-resonant responses for vortex-induced vibration of a long slender cylinder

Experimental results of the dual-resonant and non-resonant responses are presented for vortex-induced vibrations(VIV)of a long slender cylinder.The cylinder has a diameter of 10mm and a length of 3.31 m,giving an aspect ratio of 331.The cylinder was towed by a carriage with the velocity up to 1.5 m/s,with the Reynolds number varying from 2500 to 38000.Three different weights were used to provide the initial tension.Dual resonance means that resonance occurs simultaneously in both the cross-flow(CF)and in-line(IL)directions.The experiments were conducted in two stages.At the first stage,dual-resonant dynamic features of the cylinder subjected to vortex-induced excitation were investigated.The features of CF and IL vibration amplitude,motion orbits,phase angle differences,dominant frequencies and mode order numbers are presented.At the second stage of the experiments,particular emphasis was placed on non-resonant dynamic features.The variation of multi-mode modal displacement amplitudes was investigated in detail.     

Optical coherence tomography based particle image velocimetry (OCT-PIV) of polymer flows

The measurement of spatially resolved velocity distributions is crucial for modelling flow and for understanding properties of materials produced in extrusion processes. Traditional methods for flow visualization such as particle image velocimetry (PIV) rely on optically transparent media and cannot be applied to turbid polymer melts. Here we present optical coherence tomography as an imaging technique for PIV data processing that allows for measuring a sequence of time resolved images even in turbid media. Time-resolved OCT images of a glass-fibre polymer compound were acquired during an extrusion process in a slit die. The images are post-processed by ensemble cross-correlation to calculate spatially resolved velocity vector fields. The results compared well with velocity data obtained by Doppler-OCT. Overall, this new technique (OCT-PIV) represents an important extension of PIV to turbid materials by the use of OCT.     

DISPERSION OF WAVES IN IMMERSED LAMINATED COMPOSITE HOLLOW CYLINDERS

A layer element method (LEM) is presented for analyzing frequency and group velocity dispersive behaviours of waves in a laminated composite cylinder surrounded by a fluid. The LEM applies finite elements to model the radial displacement of the cylinder and the radial pressure of the fluid, and complex exponentials to express the axial and circumferential displacements of the cylinder as well as the axial and tangential pressures of the fluid. The dispersive equation for the fluid-loaded cylinder follows from variational techniques. The frequency and group velocity dispersive relationships of the fluid-coupling cylinder are obtained by means of the Rayleigh quotient. Numerical results are given for hybrid laminated composite cylinders and cylindrical shells submerged in water. The addition of the fluid is proven to have considerable impact on the group velocity spectra of waves in laminated composite cylinders.     

基于POD方法开缝圆柱绕流流场的研究

利用粒子成像测速技术（particle image velocimetry,PIV）,在水槽中探究缝隙对圆柱流场结构的影响,应用频谱分析和本征正交分解（proper orthogonal decomposition,POD）方法,研究了开缝圆柱流场相干结构.实验Reynolds数范围内,缝隙的"吹吸"作用从根本上改变了圆柱绕流近区尾流结构,前6阶模态形态是流场中最主要的相干结构.第1,2阶模态形态控制着圆柱绕流流场涡街相继脱落过程,1或2阶模态系数为尾迹涡的固有频率;第3,4阶模态形态控制着脱落旋涡沿流向方向能量运输;第5,6阶模态形态中的同向涡旋结构作用于旋涡缓慢脱离柱体这一过程,并对旋涡能量起着衰减作用.      

Wake-boundary layer interaction behind an elliptic cylinder at different Reynolds numbers

In this paper, hot-wire anemometry (HWA) is used to experimentally investigate interactions between a fully developed turbulent boundary layer and wake of an elliptic cylinder where axis ratio (AR) of the cylinder is 2. The elliptic cylinder was located inside and outside a turbulent boundary layer with a thickness (δ) of 0.38B. Furthermore, experiments were conducted at different Reynolds numbers (13,250 and 26,500) based upon the smallest cylinder diameter (B). Mean velocity, turbulence intensity and higher-order central moments of velocity signals (i.e. skewness and flatness) measurements were performed using HWA upon wake-boundary layer interactions on a flat plate. Results showed that profiles of stream-wise mean velocity and turbulence intensity were greatly dependent on gap ratio (G/B) and Reynolds number (Re) in near-wake region. It was also observed that, except for G/B = 0.1, the wake-boundary layer interactions were faster at Reynolds number of 26,500 rather than 13,250. The interactions occurred earlier upon fluctuating the velocity rather than the case where a fixed mean velocity was considered. The results further show that an increase in the gap ratio increases Strouhal number almost independent of δ/B. Behind the cylinder, relatively smaller wake region was obtained at Re = 26,500 rather than Re = 13,250, where the velocity profiles quickly converged to the flat plate boundary layer velocity profiles.     

HL-2A装置快速扫描气动探针的研制和运用

快速扫描气动探针已在HL- 2A 装置上用于对边缘等离子体参数的径向分布的测量, 特别是刮离层等离子体参数的特征长度和扰动的测量。该系统采用精密的气动气缸驱动带有探针组件的长驱动杆, 其最快速度可在60 ms 时间内水平扫描8 cm 的距离。探针信号测量具有1MHz 的快速时间响应和0. 04 mm 的空间分辨率。可靠地测量了HL- 2A 装置边缘电子温度和密度的时空分布。     

旋转扫描式成像光谱仪高光谱的几何变形矫正

Offner成像光谱仪是一种线推扫式成像系统,需要光谱仪与物体之间存在相对移动,从而记录整个区域的光谱和形貌信息。在光谱仪镜头前放置一块反射镜进行旋转扫描,也可以对大尺度物体进行高光谱成像,并且相机固定不动。然而旋转扫描时,记录的高光谱图存在较大的几何误差。该工作分析一般情况下Offner成像光谱仪单次拍摄得到的物点和像点的投影关系;根据投影关系,以旋转角为变量,分析物点在成像面上的投影分布,给出图像几何变形的矫正方法。在成像光谱仪上设计并安装了反射镜旋转扫描装置,进行旋转扫描实验,通过矫正算法,得到了清晰的高光谱图。     

光学设计性实验研究

介绍PASCO实验平台在光学设计性实验中的应用。在PASCO实验平台上设计并完成了单缝衍射、双缝干涉和偏振等实验。用软件对数据采集处理,得出光强与位置关系曲线图。展示了PASCO平台在光学设计实验中的便捷与优势。