Alternate iterative algorithm for temperature field and concentration field reconstruction based on spectral absorption

Abstract

The invention discloses an alternate iterative algorithm for temperature field and concentration field reconstruction based on spectral absorption. First, a linearization scheme is provided for calculation of a concentration field, an original system is semi-linearized, and thus the nonlinearity of the original system is weakened; then, an alternate iteration scheme is provided for the temperature field and the concentration field to be measured, and a half of the number of unknown variables is reduced in each iteration; finally, a penalty term is introduced through an optimization technology to overcome the morbidity in the reconstruction process, regularization parameters can be adjusted automatically in each iteration, and it is guaranteed that an iterative solution converges to an exact solution. According to the alternate iterative scheme, on the premise of maintaining reconstruction precision, the computing time can be shortened remarkably, and the alternate iterative algorithm is suitable for large-scale field inversion computation.

Description

technical field [0001] The invention relates to an alternate iterative algorithm for reconstruction of temperature field and concentration field based on spectral absorption, belonging to the field of laser absorption spectroscopy. Background technique [0002] In recent years, with the country's increasing emphasis on environmental protection and the need to ensure safe and efficient industrial production, optical non-contact gas detection technology has developed rapidly. Gas detection technology based on laser absorption spectroscopy has the advantages of no preprocessing, fast response, accurate data, and simultaneous detection of multiple parameters, and has become one of the on-site on-line detection technologies currently used in many fields. [0003] Absorption spectroscopy technology uses a laser to pass through the area of ​​the flow field to be measured. When the laser frequency is the same as the transition frequency of the gas absorption component, the laser ene...

AI Technical Summary

Problems solved by technology

The filtered back-projection algorithm can obtain high-precision reconstruction results under a large number of projection rays and uniform projection angles, but the angle and number of projection rays are limited by space availability and system complexity in actual combustion field measurements

The algebraic iterative algorithm is an optimization algorithm based on an iterative solution strategy. It can be used for incomplete projection data or projections with non-uniform distribution. The calculation speed is fast, but it needs to increase the number of projections in different directions and cannot be used at the same time. Information on multiple absorption lines

The sequential quadratic programming algorithm has the overall convergence while maintaining the local super-1 convergence, and the search efficiency is high, but it is extremely sensitive to the initial value, and it is easy to fall into the local optimum and fail to obtain the global optimal solution

The simulated annealing algorithm improves the accuracy and stability of the temperature field and concentration field reconstruction results by increasing the measured value of the gas absorption spectrum on a single optical path. The overall reconstruction effect is better than the above algorithm, but it belongs to the random search optimization algorithm, and the calculation efficiency is low. , takes too long

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