Diode Laser Absorption Tomography of 2D Supersonic Flow

Tunable diode laser absorption spectroscopy (TDLAS) shows promise for in situ monitoring of oxygen mass-flux in uniform, high-speed flows as has been previously demonstrated. However, the dynamic nature of typical flows of supersonic combustors, gas turbine engines and augmenters can also lead to inhomogenities that cannot be captured by a single TDLAS measurement because of its line-of-sight nature. Instead, multiple measurements varied over several spatial locations must be made to identify the inhomogenities that develop and consequently more accurately measure the mass-flux. A key question is how to minimize the number of beam-paths required to obtain useful tomographic information about the flow. In this paper, this question is addressed using Tomographic Reconstruction by Karhunen-Loeve Basis Functions (TRKB) better known as principle components analysis (PCA) as well as vector quantization. Specifically, steadystate CFD is used to form a training set of 2D profiles of oxygen and water concentrations in the isolator section of the supersonic combustion facility in research cell 18 at WrightPatterson AFB. This training set is then used to create an optimal set of basis functions that allow tomographic reconstruction to be performed with a limited number of TDLAS beam paths. This approach is also verified for the case of a laboratory scale flat flame McKenna burner. Good agreement is found between the reconstructed profiles and previously measured values for the temperature and concentration in the center flame zone as well as the ambient air.

[1]  H. Sebastian Seung,et al.  Learning the parts of objects by non-negative matrix factorization , 1999, Nature.

[2]  Charles Audet,et al.  Analysis of Generalized Pattern Searches , 2000, SIAM J. Optim..

[3]  Yuan-Pern Lee,et al.  Wavenumbers, strengths, widths and shifts with pressure of lines in four bands of gaseous 16O2 in the systems a1Δg−X3Σg− and b1Σg+−X3Σg− , 2000 .

[4]  R. Hanson,et al.  Diode-Laser Absorption Sensor for Line-of-Sight Gas Temperature Distributions. , 2001, Applied optics.

[5]  Kuo-Cheng Lin,et al.  Diode Laser Diagnostics for High Speed Flows , 2006 .

[6]  W. Meier,et al.  A flat flame burner as calibration source for combustion research: Temperatures and species concentrations of premixed H2/air flames , 1994 .

[7]  F. Gouldin,et al.  Tomographic Analysis of Unsteady, Reacting Flows: Numerical Investigation , 1998 .

[8]  Douglas A. Greenhalgh,et al.  A combustion temperature and species standard for the calibration of laser diagnostic techniques , 2006 .

[9]  Robert M. Gray,et al.  An Algorithm for Vector Quantizer Design , 1980, IEEE Trans. Commun..

[10]  Laurence S. Rothman,et al.  The HITRAN molecular spectroscopic database and HAWKS (HITRAN atmospheric workstation) , 1998, Defense, Security, and Sensing.

[11]  Clemens F. Kaminski,et al.  A flat flame burner for the calibration of laser thermometry techniques , 2006 .

[12]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[13]  J. A. White,et al.  A Psuedo-Temporal Multi-Grid Relaxation Scheme for Solving the Parabolized Navier-Stokes Equations , 1999 .

[14]  F. Gouldin,et al.  Tomographic reconstruction of 2-D absorption coefficient distributions from a limited set of infrared absorption data , 1998 .

[15]  Laurence S. Rothman,et al.  Reprint of: The HITRAN molecular spectroscopic database and HAWKS (HITRAN Atmospheric Workstation): 1996 edition , 1998 .

[16]  Avinash C. Kak,et al.  Principles of computerized tomographic imaging , 2001, Classics in applied mathematics.

[17]  Tarun Mathur,et al.  Near-infrared diode laser absorption diagnostic for temperature and water vapor in a scramjet combustor. , 2005, Applied optics.