Raman-Rayleigh-LIF measurements of temperature and species concentrations in the Delft piloted turbulent jet diffusion flame

Abstract

We report a series of Raman-Rayleigh-LIF measurements in two turbulent natural-gas jet diffusion flames produced by the Delft piloted jet diffusion flame burner. The main objective of the Raman-Rayleigh-LIF measurements was to obtain detailed information on the major species concentrations in the flames. The measurements provide simultaneous data on temperature, the concentrations of the major species and the radicals OH and NO and mixture fraction. The application of the Raman technique in the undiluted naturalgas flames proves to be very challenging because of the high fluorescence interference levels. The interference contributions to the recorded Raman signals are identified and subtracted using empirical correlations between the Raman signals and the signals on fluorescence interference monitor channels. The calibration and data reduction of the Raman-Rayleigh and LIF signals are discussed in detail. The resulting dataset compares excellently with data from previous experiments. Because the Raman-Rayleigh-LIF data provide quantitative concentrations and accordingly quantitative mixture fractions, they form a valuable and useful extension of the existing database for the Delft piloted jet diffusion flame burner.

Flow and Mixing Fields for Transported Scalar PDF Simulations of a Piloted Jet Diffusion Flame (‘Delft Flame III’)

“…The differences between the mean mixture fraction profiles are explained by means of the mean axial velocity component again, in the context of mean convection-diffusion equation (3). The PPDF results are better.…”

“…The spontaneous emission of the pilot flames shows that the three-dimensional effects already disappear after a few millimeters [3]. The product streams of the individual pilot flames then combine to form a cylindrically symmetric stream, which strongly suggests that the three-dimensionality is not critical for flame stabilization.…”

“…In this paper, numerical results are presented for the piloted jet diffusion flame, known as 'Delft Flame III' [1][2][3][4]. This flame, with relatively strong interaction between turbulence and chemistry, is a target test flame in the series 'International Workshop on Measurements and Computations of Turbulent Non-premixed Flames (TNF) ' [5].…”

“…Results of the combination of k-ε model with round jet correction and presumed shape mixture fraction PDF models are contained in [1] and [8]. However, the experimental data of mean temperature used for validation purposes in these early works in the mean time have been superseded by more accurate measurements [3,4]. As a consequence, when comparing with the new measurements the agreement with the assumed shape PDF results is not so good as found in [1,7,8].…”

Laser-Induced Fluorescence Detection of Hot Molecular Oxygen in Flames Using an Alexandrite Laser

“…In this context, the available methods include laser-induced fluorescence (LIF) using excitation at 193 or 226 nm; [8][9][10][11][12][13] vibrational and pure-rotational coherent anti-Stokes Raman scattering (CARS) spectroscopy; [14][15][16][17] and spontaneous Raman scattering. [18][19][20][21][22] Assuming thermal equilibrium, it is possible to determine the population of excited oxygen from a combined measurement of the ground state population and the temperature. However, this assumption can hardly be justified in the vicinity of the reaction zone in a flame where the complex chemistry produces nonequilibrium species such as radicals in electronically excited states.…”