The Reconstruction Of Two-dimensional Distributions Of Gas Concentration And Temperature Based On Tunable Laser Absorption Spectroscopy

In the study of combustion and the process of optimizing combustion control, the two-dimensional distribution of flame temperature and gas concentration is undoubtedly of great significance. The Tunable Laser Absorption Spectroscopy (TDLAS), developed in the last20years, is a new type of optical non-contact measurement with high sensitivity, fast response, anti-interference ability and other characteristics. But its measurement is mostly the average of gas concentration and temperature in the whole optical path. When the gradient of the gas concentration and temperature is large in the measurement area, this approach obviously does not reflect the actual situation of the detect area.A24-beam laser measurement system and flat burner is designed in the article, and using two H2O absorption lines (1397.75nm and1397.87nm) detects the methane/air premixed flat flame, then we obtain the absorption signals of the two absorption lines by use of a24-channnel simultaneous acquisition procedure. According to the data, we reconstruct the two-dimensional distribution of flame temperature and H2O vapor concentration by use of the procedure based on Algebraic Iterative Tomography (ART). In order to verify the accuracy of the results, the correctness of procedure is verified by numerical simulation.After reconstructing the two-dimensional distribution of gas concentration, we reconstruct the two-dimensional distribution of flame temperature and H2O vapor concentration by use of the procedure based on Algebraic Iterative Tomography (ART). With the purpose of verifying the accuracy of the results, the correctness of procedure is verified by numerical simulation and comparing with temperature measured with thermocouple (maximum error is about72K). Finally, the reconstructions of the H2O vapor concentration by use of the two H2O absorption lines is compared with each other and the selection criteria is given by theoretical analysis. Using the method to reconstruct the two-dimensional distribution of flame temperature and gas concentration is quick and accurate, so it can provide important data to optimize combustion control and improve the efficiency of combustion to achieve the target of emission reduction.