Design The Software Based On TDLAS For Two-Dimensional Temperature Field Distribution Inversion

In the study of combustion flow field diagnostics, the flame temperature is an important physical quantity. It is one of the important parameters to measure the combustion efficiency. Measurement of combustion temperature fields has important significance for engine combustion state diagnosis,improve combustion efficiency and reduce emissions of pollutants. Develop the inversion software for the two dimensional temperature field distribution,has important significance to the measurement of non uniform flow temperature.Tunable diode laser absorption spectroscopy (TDLAS, tunable diode laser absorption spectroscopy) technique has the advantages of response speed, high sensitivity, high precision and non-contact type measurement,it is a high selectivity, high resolution spectroscopy and for the combustion flow field diagnosis,it does not interfere with the measured flow field.With TDLAS technology and computer tomography (CT) combined,they can be reached the two-dimensional flow field distribution of combustion space.This paper developed a two-dimensional temperature field distribution of TDLAS inversion software based on visual software,the software is easy to process operation for non professional personnel, the main content of this paper includes the following several parts:1,Firstly, the thesis introduces the meaning of measuring two-dimensional temperature field,measurement method compared with the traditional measurement method and a new type of spectral analysis, in spectroscopy measurement methods, focusing on the introduction of the tunable diode laser absorption spectroscopy (TDLAS) technology characteristics and research status.2, Thesis goes from the molecular absorption spectral angle of the infrared absorption spectra of temperature measurement,the basic theory of the beer Lambert Law and molecular absorption spectral line intensity and absorption lineshape function concept, according to the study, high resolution molecular database using the HITRAN (high resolution transmission molecular absorption), combined with the python language,the procedure to select the spectral line of the HITRAN database is developed, of H2O absorption spectrum calculation, select the appropriate absorption line for as the temperature spectrum. Describes the 2 basic methods of TDLAS Technology:direct absorption spectroscopy and wavelength modulation spectroscopy technology, comparative analysis of advantages and disadvantages of the two.3, In order to development the two-dimensional temperature field distribution inversion software based on TDLAS, based on the python language developed processing the HITRAN database visualization program, the realization of the HITRAN data acquisition, SQL (database language) way to selection and processing of data, line intensity, internal partition sums, absorption coefficient and absorption spectra of three linear function display,encapsulates the data processing algorithm. Python’s cross platform and object oriented features,making the algorithm easy to expand.Analysis and comparison of the Python language compared to Matlab mathematical tools in processing Hitran data on the advantage.4, Based on the analysis of the computed tomography scans of the two types of algorithms,a detailed explanation of the use the algebra reconstruction algorithm (ART, algebraic reconstruction technique), based on the python language, combined with numpy numerical calculation base and Matplotlib drawing library. First, the paper introduces the two-dimensional temperature field numerical simulation distribution, in the given integral absorbance based retrieved after two-dimensional temperature field distribution and the interpolation of distribution, and then the inversion after the addition of 2% noise distribution. Through the statistical analysis of the data, obtains the temperature reconstruction results with the original temperature distribution deviation.