An integrated sensor technology for measurements of specific heat ratio of combustion gases in supersonic flow
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摘要: 介绍了为测量燃烧气体的比热比而设计的包含了皮托管和激光光束跟踪系统的集成测量系统。该系统通过测量压力比和穿过皮托管前正激波的激光折射角来获得比热比,从而免使用复杂而昂贵的光相色谱仪器。激光光束折射角通过两台CCD摄像头和移动空间坐标测量系统(MScMS)来准确记录激光光束折射角。密度比通过Gladstone-Dale关系和Snell律来获得。由此,通过所获得的跨激波的压力比和密度比可以定量确定比热比。这一技术可有效降低比热比测量时间。本文对激光光束跟踪系统和皮托管所带来的不确定性进行了分析,结果表明在总温不超过1000K时系统不确定性低于5.5%。可行性分析表明该技术可以实现,但仍有部分技术问题需要在实施前解决。Abstract: We present an integrated probe system for measuring the specific heat ratioγof combustion gases by combining Pitot tube and laser beam tracking system.The key benefit of the measurement system is the elimination of the complicated gas chromatography apparatus.The pressure ratio and the angle of refraction of a laser beam across the normal shock wave generated by Pitot tube are simultaneously measured with this system.The angle of refraction of the laser beam is expected to be accurately recorded by the laser tracking system consisting of two CCD cameras and a mobile spatial coordinate measuring system (MScMS).Moreover,the density rati-o across the shock wave is deduced with Gladstone-Dale relation and Snell’s law.The specific heat ratioγis accordingly quantified by its relation to the pressure ratio and the density ratio across the shock wave.This technique may effectively reduce the time taken to obtainγ.Uncer-tainty estimation shows that the uncertainty brought by the laser beam tracking system and Pitot tube measurement are limited within 5 .5%for any Mach number if the stagnation temperature is lower than 1000K.Feasibility analysis present that the technique is physically realizable but a few technical issues need to be addressed before it can be implemented.
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