Jatana Gurneesh S, Magee Mark, Fain David, Naik Sameer V, Shaver Gregory M, Lucht Robert P
Appl Opt. 2015 Feb 10;54(5):1220-31. doi: 10.1364/AO.54.001220.
A diode-laser-absorption-spectroscopy-based sensor system was used to perform high-speed (100 Hz to 5 kHz) measurements of gas properties (temperature, pressure, and H(2)O vapor concentration) at the turbocharger inlet and at the exhaust gas recirculation (EGR) cooler exit of a diesel engine. An earlier version of this system was previously used for high-speed measurements of gas temperature and H(2)O vapor concentration in the intake manifold of the diesel engine. A 1387.2 N m tunable distributed feedback diode laser was used to scan across multiple H(2)O absorption transitions, and the direct absorption signal was recorded using a high-speed data acquisition system. Compact optical connectors were designed to conduct simultaneous measurements in the intake manifold, the EGR cooler exit, and the turbocharger inlet of the engine. For measurements at the turbocharger inlet, these custom optical connectors survived gas temperatures as high as 800 K using a simple and passive arrangement in which the temperature-sensitive components were protected from high temperatures using ceramic insulators. This arrangement reduced system cost and complexity by eliminating the need for any active water or oil cooling. Diode-laser measurements performed during steady-state engine operation were within 5% of the thermocouple and pressure sensor measurements, and within 10% of the H(2)O concentration values derived from the CO(2) gas analyzer measurements. Measurements were also performed in the engine during transient events. In one such transient event, where a step change in fueling was introduced, the diode-laser sensor was able to capture the 30 ms change in the gas properties; the thermocouple, on the other hand, required 7.4 s to accurately reflect the change in gas conditions, while the gas analyzer required nearly 600 ms. To the best of our knowledge, this is the first implementation of such a simple and passive arrangement of high-temperature optical connectors as well as the first documented application of diode-laser absorption for high-speed gas dynamics measurements in the turbocharger inlet and EGR cooler exit of a diesel engine.
基于二极管激光吸收光谱的传感器系统用于在柴油发动机的涡轮增压器入口和废气再循环（EGR）冷却器出口处进行气体特性（温度、压力和H₂O蒸汽浓度）的高速（100 Hz至5 kHz）测量。该系统的早期版本曾用于柴油发动机进气歧管中气体温度和H₂O蒸汽浓度的高速测量。使用一台1387.2 N·m可调谐分布反馈二极管激光器扫描多个H₂O吸收跃迁，并使用高速数据采集系统记录直接吸收信号。设计了紧凑的光学连接器，以便在发动机的进气歧管、EGR冷却器出口和涡轮增压器入口进行同步测量。对于涡轮增压器入口处的测量，这些定制光学连接器采用简单的无源布置，可在高达800 K的气体温度下工作，其中温度敏感部件使用陶瓷绝缘体保护免受高温影响。这种布置通过消除任何主动水冷却或油冷却的需求，降低了系统成本和复杂性。在发动机稳态运行期间进行的二极管激光测量结果与热电偶和压力传感器测量结果的偏差在5%以内，与从CO₂气体分析仪测量得出的H₂O浓度值的偏差在10%以内。还在发动机瞬态过程中进行了测量。在一次这样的瞬态过程中，引入了燃油供应的阶跃变化，二极管激光传感器能够捕捉到气体特性在30 ms内的变化；另一方面，热电偶需要7.4 s才能准确反映气体状况的变化，而气体分析仪则需要近600 ms。据我们所知，这是首次采用如此简单的无源高温光学连接器布置，也是首次记录二极管激光吸收在柴油发动机涡轮增压器入口和EGR冷却器出口高速气体动力学测量中的应用。
