Water Vapor Absorption Thermometry for Practical Combustion Applications
Date
2009-06-24Author
Caswell, Andrew W.
Advisor(s)
Sanders, Scott T.
Metadata
Show full item recordAbstract
Thermometry in combustion applications by means of laser absorption spectroscopy is a well
established diagnostic. The experimental simplicity and wealth of knowledge that can be
readily gained from an absorption spectrum makes it often times the diagnostic of choice
when interrogating the flow fields of practical combustion devices such as internal
combustion engines.
This project develops techniques for optimizing the design of absorption based sensors by
providing strategies for selecting optimal wavelengths in order to improve thermometry.
Descriptive relations are derived in order to predict the performance of an absorption based
sensor and through numerical optimization, ideal selections of wavelengths can be made.
Furthermore, this work applies novel hyperspectral lasers to practical combustion
environments in order to infer gas properties based on direct absorption spectroscopy. The
measurements are designed for high-speed (30 kHz and up) data rates of useful engineering
parameters such as temperature and species concentration. Measurements have been
performed across the cylinder of an optically accessible HCCI engine using a rapidly-swept
(5 ?s measurement time) broad wavelength (1333-1377 nm) tunable laser. Temperature
results were obtained at 100 kHz with 0.25% RMS precision at a temperature of 1970 K.