Development of Aceton Laser Induced-Fluorescence Diagnostic Method for the Quantitative Measurement of Supersonic Flows

激光诱导荧光（LIF）为超声速和跨音速流动的测量提供了一种强有力的诊断技术。激光和示踪剂材料的几种组合是已知的。一氧化氮在受到由染料激光器获得的紫外光照射时发射荧光。然而，一氧化氮是有毒的，此外，它是一种活性分子并与氧气反应。氧通过ArF准分子激光器发射LIF。这可以避免一氧化氮的问题，但荧光产率通常很低。氩离子激光激发的碘提供了另一种LIF诊断方法。其荧光产额远大于上述两种，但由于碘的腐蚀性限制了其在流场的应用，近年来丙酮LIF法引起了相当大的关注。丙酮无腐蚀性，毒性弱，释放出强LIF。丙酮激光诱导荧光法是一种很有前途的定量诊断工具，用于测量可压缩流。然而，它还没有被证实，这种方法可以测量可压缩流，因为在低温条件下的丙酮的荧光特性没有得到很好的理解。在这项研究中，研究是做检查的可能性，这种方法作为诊断工具，以测量数密度的超音速流的温度低于大气。低温条件是由喷嘴喷出的欠膨胀超音速射流造成的。射流中的LIF强度由CCD摄像机测量，并与通过将Thurber等人的多步衰减模型扩展到低温区域计算的理论强度进行比较。这种比较使得有可能检查扩展模型的有效性。使用这个检查模型，我们估计LIF测量的数密度的温度变化的灵敏度，并检查测量的准确性。

Laser-induced fluorescence (LIF) offers a powerful diagnostic technique for the measurement of supersonic and transonic flows. Several combinations of lasers and tracer materials have been known. Nitric oxide emits fluorescence when irradiated by ultraviolet light obtained by a dye laser. Nitric oxide, however, is toxic and, in addition, it is an active molecule and reacts with oxygen. Oxygen emits LIF by an ArF excimer laser. This can avoid the problems of nitric oxide, but the fluorescence yield is usually very. Iodine excited by an argon ion laser provides another LIF diagnostic method. The fluorescence yield of this is much larger than the above two, but the application to the flow field is limited by the corrosive nature of iodine.In recent years, the acetone LIF method has attracted considerable attention. Acetone is non-corrosive, weak toxic and emits strong LIF. The acetone LIF method is promising as a quantitative diagnostic tool for the measurement of compressible flows. However, it has not been verified that this method can measure compressible flows because fluorescence characteristics of acetone under low temperature conditions are not well understood. In this research, the study is done to check the possibility of this method as a diagnostic tool to measure the number density in supersonic flows where temperature is lower than the atmosphere. Low temperature condition is made by underexpanded supersonic jets emanating from nozzles. The LIF intensity in the jets is measured by the CCD camera and compared with the theoretical intensity calculated by extending the multi-step decay model of Thurber, et al. to a low temperature regime. This comparison makes it possible to check the validity of the extended model. Using this checked model, we estimate the sensitivity of the LIF-measured number density to change in temperature, and examine the accuracy in measurement.