Improving the reconstruction accuracy of tomographic absorption spectroscopy sensor by optimizing laser beam...

Area of Science:

• Combustion diagnostics
• Optical diagnostics
• Tomographic imaging

Background:

• Tomographic absorption spectroscopy (TAS) is valuable for combustion diagnostics, reconstructing spatial distributions of temperature and species concentration.
• The accuracy of TAS is highly dependent on the geometric arrangement of laser beams, particularly when beam numbers are limited.
• Existing beam arrangements may not fully utilize available beams, leading to suboptimal reconstruction accuracy.

Purpose of the Study:

• To develop an optimized laser beam arrangement method for tomographic absorption spectroscopy (TAS).
• To enhance the utilization efficiency of limited laser beams for improved reconstruction accuracy.
• To provide a simpler and more intuitive approach to beam arrangement optimization.

Main Methods:

• A novel cost function was designed, integrating the beam number matrix (BNM) and total weight matrix (TWM).
• A simulated annealing algorithm was employed to determine the optimal beam arrangement based on the defined cost function.
• Numerical simulations were conducted using a 12-beam TAS sensor to evaluate performance against traditional and orthogonality-optimized arrangements.
• The method was applied to reconstruct temperature distributions in asymmetric butane flames.

Main Results:

• The BNM-TWM optimized beam arrangement demonstrated lower reconstruction errors compared to orthogonal and OD-optimized arrangements in simulations.
• Significant improvements were observed, especially when orthogonal and OD-optimized arrangements performed suboptimally.
• The optimized arrangement successfully reconstructed temperature distributions of asymmetric butane flames, outperforming ineffective parallel beam distributions.
• Reconstructed flame center temperatures showed less than a 3% difference compared to thermocouple measurements.

Conclusions:

• The proposed BNM-TWM beam arrangement optimization method effectively enhances TAS accuracy under limited beam conditions.
• This optimization strategy offers a more efficient use of limited beams for tomographic reconstruction.
• The method shows potential for broader application in tomographic imaging systems beyond combustion diagnostics.