Characteristics of Flowfield and Output Power of a Supersonic Flow Chemical Oxygen-Iodine Laser

超音速流化学氧碘激光器的流场和输出功率特性

基本信息

批准号：
10450075
负责人：
MASUDA Wataru
金额：
$ 3.33万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Possibility of mixing enhancement of iodine with singlet oxygen by means of acoustic excitationwas examined using a jet-diffusion flame of methane. The jet-diffusion flame was acoustically excited by monotone sound wave generated by a loud speaker. Applying the acoustic excitation using a specific range of frequency that corresponds to the Strouhal number St=0.15 to 0.6, the jet diffusion flame has peculiar features. In the mode of increasing the jet velocity, the flame shortens its original length and widened in the incident direction of sound wave. Decreasing the jet velocity, the jet velocity at which the reattachment of lifted flame occurs is lowered significantly owing to the acoustic excitation, and the lifted flames with elliptical cross sections or branched tips are discovered in the specific region of the velocity and sound frequency.A Q-switched supersonic flow chemical oxygen-iodine laser is also simulated by solving the gas flow model coupled with the precis e chemical kinetic model and the optical model. The model includes the effects of hyperfine relaxation and velocity cross relaxation for iodine atoms. The effects of such relaxations and nonuniformity of the three-dimensional flow field on the power extraction were discussed. The results show that the peak power under the influence of hyperfine relaxation and velocity cross relaxation, which is normalized to the corresponding continuous wave value, is 15. It agrees fairly well with common experimental results of Q-switched chemical oxygen-iodine laser operation. The peak power of the pulse in the three-dimensional flow field is considerably small compared to that in the equivalent one-dimensional flow field and the pulse is widened roughly twice due to insufficient mixing, shock waves, expansion waves and wakes.

使用甲烷喷射扩散火焰检查了通过声激发增强碘与单线态氧混合的可能性。喷射扩散火焰由扬声器产生的单调声波以声学方式激发。使用对应于斯特劳哈尔数 St=0.15 至 0.6 的特定频率范围施加声激励，射流扩散火焰具有独特的特征。在增加射流速度的情况下，火焰缩短了原来的长度，并在声波入射方向上加宽。降低射流速度，由于声激励，发生升起火焰重新附着的射流速度显着降低，并且在速度和声频的特定区域内发现具有椭圆形横截面或分支尖端的升起火焰。通过求解气体流动模型，结合精确的化学动力学模型和光学模型，对调Q超音速流化学氧碘激光器进行了模拟。该模型包括碘原子的超精细弛豫和速度交叉弛豫的影响。讨论了三维流场的这种松弛和不均匀性对功率提取的影响。结果表明，超精细弛豫和速度交叉弛豫影响下的峰值功率（归一化为相应的连续波值）为15，与常见的调Q化学氧碘激光器实验结果吻合较好。与等效的一维流场相比，三维流场中的脉冲峰值功率相当小，并且由于不充分的混合、冲击波、膨胀波和尾流，脉冲展宽了大约两倍。