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中国物理学会期刊

基于混合飞秒/皮秒相干反斯托克斯拉曼散射的动态高温燃烧场温度测量

CSTR: 32037.14.aps.70.20211144

Thermometry in dynamic and high-temperature combustion filed based on hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering

CSTR: 32037.14.aps.70.20211144
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  • 温度测量对燃烧过程中的污染控制与节能减排具有重要意义, 而实际应用中复杂的动态高温燃烧场对温度测量技术的测量精度与响应速度提出了严格的要求. 相干反斯托克斯拉曼散射技术作为一种较为先进的光谱测温技术, 具有较高的空间分辨率, 可以在高温环境下实现准确的温度测量, 具有应用于复杂燃烧场的潜力. 针对复杂的动态高温燃烧场的测温需求, 本文提出了一种基于二次谐波带宽压缩方法的混合飞秒/皮秒相干反斯托克斯拉曼散射测温方法, 实现了对动态高温燃烧场温度的准确测量与动态响应. 实验中利用标准燃烧器模拟了1700—2200 K温度范围内的动态高温燃烧场, 利用该测温方法, 以千赫兹的光谱采集速率, 对模拟的动态火焰的温度进行了连续70 s测量. 测量结果显示, 该方法在高温下温度测量的相对误差小于1.2 %, 相对标准偏差小于1.8 %, 同时能动态追踪0.2 s内的温度变化过程, 验证了该方法测温的准确性、稳定性以及响应速度, 为复杂的动态高温燃烧场的温度测量提供了一种新的测量方案.

     

    Temperature, as an important parameter in combustion diagnostic process, will directly affect the combustion efficiency and the generation of combustion products. The accurate measuring of combustion temperature and then controlling of combustion state can not only contribute to avoiding the generation of harmful waste gas, such as carbon monoxide (CO) and oxynitride (NOx), but also improve the combustion efficiency, thereby saving the energy. However, in practical applications, dynamic and high-temperature combustion field has strict requirements for measurement accuracy and response speed of the thermometry technology. As an advanced spectral thermometry technology, coherent anti-Stokes Raman scattering (CARS) has a much higher spatial resolution, and can achieve accurate temperature measurement in high-temperature environment, so CARS has the potential applications in complex combustion field. For the temperature measurement requirements in the complex dynamic and high-temperature combustion field, we demonstrate a hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering thermometry method through using the second harmonic bandwidth compression method, and achieve accurate measurements and dynamic response to temperature in dynamic and high-temperature combustion field. By using the narrow-band picosecond pulse obtained from the sum frequency process of femtosecond pulse in the BBO crystal as a probe pulse, this thermometry method can achieve single-shot, 1-kHz temperature measurement in high-temperature flame. We utilize the standard burner to simulate dynamic combustion field in a range of 1700–2200 K by changing the equivalence ratio quickly, and carry out continuous temperature measurement in 70 s by our thermometry method in this simulated dynamic and high-temperature flame. The least square method is used to fit the theoretical spectrum library to the actual single spectrum, and the fitting temperature corresponding to the actual single spectrum is obtained from the curve of fitting error. The continuous temperature measurements in 70 s exhibit superior performance in dynamic and high-temperature flame with a temperature inaccuracy less than 1.2% and a precision less than 1.8% at four different temperatures, and can track the temperature variation process within 0.2 s dynamically. These results verify the accuracy, stability and response speed in dynamic and high-temperature environment, and provide a new system scheme for thermometry in practical harsh combustion field.

     

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