Font Size: a A A

Optical diagnostics for partially premixed flames

Posted on:2003-07-22Degree:Ph.DType:Dissertation
University:University of Illinois at ChicagoCandidate:Xiao, XudongFull Text:PDF
GTID:1462390011485445Subject:Engineering
Abstract/Summary:PDF Full Text Request
This investigation pertains to the development of optical techniques for combustion applications, including analog and digital holographic interferometry, and rainbow schlieren deflectometry. These techniques are used to investigate partially premixed flames (PPFs) stabilized either on a Wolfhard-Parker slot burner or on an axisymmetric coannular burner. The interferometric and deflectometric methods measure the refractive index in the flames. In order to interpret the refractive index measurements a variety of counterflow partially premixed flames are simulated by using detailed descriptions for the species' thermophysical properties and the flame chemistry. Based on these simulations, we first establish that a relation can be developed to model the refractive index as a function of temperature in PPFs, which contains relatively minor errors that depend upon the rich-side equivalence ratio. Larger errors are observed in the case of nonpremixed flames. Thereafter, a rational approach for determining the local mixture fraction, species distribution, and temperature in these flames is constructed. Here, a conserved scalar ξ, that transforms the flame structure from a spatial to a generic distribution, is inferred from the refractive index distribution using a flamelet library. Consequently, the deduction of the density, temperature, and composition in two-dimensional PPFs becomes feasible. The digital holographic interferometry technique is based on the principles of Fourier optics. The spectral features of holograms are used to develop two numerical methods for hologram reconstruction. The results show that both methods provide an accurate reconstruction of the phase image associated with a simulated flame.
Keywords/Search Tags:Partially premixed, Flame, Refractive index
PDF Full Text Request
Related items