Wave Propagation Analysis in a Pressure-Wave-Refrigerator

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

CARS���超音速燃烧研究中的应用

报道了氮、氧和水的Q支CARS���以及氢的S(5)和S(6)纯转动CARS���测量结果,并用来确定超音速燃烧火焰中的温度及氧的浓度;用水的Q支CARS���得到共振与非共振谱积分面积比随浓度的变化曲线.提出并发展的同时测量氢和氧的CARS���新方法,为同时测量火焰温度和氢、氧浓度提供了一条途径,特别对不含氮的燃烧系统更具重要意义.

Multiplex CARS measurements in supersonic H-2/air combustion

H-2 and O-2 multiplex coherent anti-stokes Raman spectroscopy (CARS) employing a single dye laser has been explored to simultaneously determine the temperature and concentrations of H-2 and O-2 in a hydrogen-fueled supersonic combustor. Systematic calibrations were performed through a well-characterized H-2/air premixed flat-flame burner. In particular, temperature measurement was accomplished using the intensity ratio of the H-2 S(5) and S(6) rotational lines, whereas extraction of the H-2 and O-2 concentrations was obtained from the H-2 S(6) and O-2 Q-branch, respectively. Details of the calibration procedure and data reduction are discussed. Quantification of the supersonic mixing and combustion characteristics applying the present technique has been demonstrated to be feasible. The associated detection limits as well as possible improvements are also identified.

氢／空气预混平面火焰CARS���度测量

介绍了一套用于燃烧研究中对温度和成分浓度测量进行校准的氢／空气预混平面火焰燃烧４系统。采用氮ＣＡＲＳ技术对氢／空气预混平面火焰温度进行了系统的测量，包括不同当量比条件下的温度分布，温度的纵向和横向空间分布。结果表明，氮ＣＡＲＳ测温与氢／空气预混平面火焰的理论计算温度之间的误差为３.４％，而在燃烧炉表面上方１ｍｍ以上的空间属于火焰的温度均匀区，温度的不均匀性约为１.８％。

同时测量氢氧CARS���谱确定火焰温度和氢氧浓度的研究

利用YAG激光器和一台染料激光器同时测量了氢/空气预混平面火焰中氢氧CARS���谱。从氢的S(5)和S(6)支纯转动线的强度比获得火焰温度，并与由氮的CARS���谱得到的温度进行了实验校验。氢和氧的浓度分别由氢的S(6)支和氧的Q支光谱求得，并利用氢/空气预混平面火焰的局部热力学平衡计算对所得浓度进行了校验。温度的校验误差为4%，而氢氧浓度的校验误差分别为14%和12%。

USED CARS���量对撞式扩散火焰的温度分布

介绍了用USED CARS���术测量对撞式甲烷/空气扩散火焰前滞止区和尾流区的温度分布剖面。在滞止区富甲烷观察到甲烷燃烧前的热解过程；尾流区温度高于滞止区温度，表明在滞止区有未完全燃烧的中间产物存在，在尾流区发现C_2及CH的光谱也证明了这一点。

同时测量氢和氧CARS���的新方法

提出一种仅需一台染料激光器即可同时测量火焰中氢和氧的CARS���的新方法。取带宽为120cm~(-1)，中心波长位于580.4nm的Stokes光束与532nm的泵浦光束相配合，同时测量氢扩散火焰中的氢和氧的CARS���，用氢的S(6)和S(5)的积分强度比确定火焰中的温度并与氮的Q支CARS���测量的温度和经过热损耗修正的热电偶测得的温度取得了相当好的一致结果。一次测出氢和氧的CARS���，避免多次测量中参数的难以重复性，提高了以温度为参数来确定浓度的准确性。

OH在火焰中浓度分布图像及与温度关系的PLIF和CARS���究

用平面激光诱导荧光(PLIF)技术测量了平面火焰炉、狭缝火焰炉的单脉冲激光诱导OH荧光。由平面荧光图可得到氢氧基相对浓度分布和它的宽度。对扩散火焰，高温区在OH带内侧；OH带的外侧则是火焰的边界，相干反斯托克斯拉曼光谱(CARS)的测量结果对此提出了有力的佐证。湍流火焰的PLIF图则清晰地显示出火焰面的不规则性。氢氧基的PLIF图像是研究火焰结构和流场的有力工具。

环形泵浦相位匹配CARS���术的匹配方式和空间分辨率的实验研究

通过对环形泵辅相位匹配方式的解剖，发现所得到的CARS���号是由多种相让匹配方式产生的，分析了各种匹配方式产生的CARS���度的份额与空间分布。通过光路设计可得到与交叉BOXCARS���比拟的空间分辨率。计算和实验都证实了两束泵浦光与斯托克斯光在透镜表面上的张角有一最佳值，这种相位匹配方式是不存在相位失配的BOXCARS���并充分利用了环形泵浦束的能量。

Wave Propagation Analysis in a Pressure-Wave-Refrigerator

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

The research of range-gated laser night vision system on cars - art. no. 68351V

The characteristic of several night imaging and display technologies on cars are introduced. Compared with the current night vision technologies on cars, Range-gated technology can eliminate backscattered light and increase the SNR of system. The theory of range-gated image technology is described. The plan of range-gated system on cars is designed; the divergence angle of laser can be designed to change automatically, this allows overfilling of the camera field of view to effectively attenuate the laser when necessary. Safety range of the driver is calculated according to the theory analysis. Observation distance of the designed system is about 500m which is satisfied with the need of safety driver range.