DEVELOPMENT OF A COMPUTER CONTROLLED SHOCK TUBE SYSTEM FOR THE STUDY OF HIGH TEMPERATURE CHEMICAL KINETICS

本研究的主要目标是开发一种反应器，以获得可靠的化学动力学数据在高温下。采用计算机控制系统使激波管自动工作。该系统的主要功能包括：1）通过监测测试段中的真空水平来控制抽空系统，2）控制驱动段中的高压气体供应和低压段中的样品气体供应，3）通过操作用于控制主活塞和辅助活塞的电磁阀来产生冲击波，4）从数字示波器传输的数据存储，确定冲击波温度和压力，通过使用单个物种的校准曲线将ARAS的观测吸收强度转换为绝对浓度，以及化学动力学分析，以及5）紧急要求（水、电和气体泄漏）的操作。性能测试已经完成，所有功能都运行得很好。激波管研究的自动控制系统成功地排除了标准型激波管由于人工操作或激波速度波动所引起的误差。这样得到的动力学数据的质量得到了很大的改善：在激波管试验中有时观察到的随机数据波动所引起的S/N比和误差，可以通过对同一激波速度下几次发射的数据进行平均来改善。此外，还利用准分子激光光解方法获得了各种原子/自由基反应的直接信息。

The main goal of this study is to develop a reactor in order to obtain reliable chemical kinetic data at elevated temperatures. A computer controll system is employed to operate a shock tube automatically. The main functions of the system include : 1) controll the evacuation system by monitoring the vacuum level in the test section, 2) controll the high pressure gas supply in the driver section and the sample gas supply in the low pressure section, 3) generation of shock waves by operating solenoid valves for controlling the main and auxially pistons, 4) data storage transfered from a digital oscilloscope, determination of the shock wave temperature and pressure, conversion of the observed absorption intensity of ARAS into the absolute concentaration by use of the calibration curves for individual species, and chemical kinetic analyzes, and 5) operation of the emergency requirements (water, electricity, and gas leakage) . Performance tests have been already finished and all the functions are working very nicely. The automatic controll system for the shock tube study has been successful in excluding the errors due to manual operation or the fluctuation of the shock speeds associated with a standard type shock tube. The quality of the kinetic data thus obtained has been extensively improved : S/N ratio and errors due to random data fluctuations some time observed in shock tube runs can be improved by averaging the data for only several shots at the same shock speed. Moreover, an excimer laser photolysis method is used to obtain : the direct information of various atom/radical reactions.