Comparisons of laser-saturated, laser-induced, and planar laser-induced fluorescence measurements of nitric oxide in a lean direct-injection spray flame

Abstract

We report quantitative, spatially resolved laser-saturated fluorescence (LSF), linear laser-induced fluorescence (LIF), and planar laser-induced fluorescence (PLIF) measurements of nitric oxide (NO) concentration in a preheated, lean direct-injection spray flame at atmospheric pressure. The spray is produced by a hollow-cone, pressure-atomized nozzle supplied with liquid heptane, and the overall equivalence ratio is unity. NO is excited by means of the Q(2)(26.5) transition of the gamma(0, 0) band. LSF and LIF detection are performed in a 2-nm region centered on the gamma(0, 1) band. PLIF detection is performed in a broad ~70-nm region with a peak transmission at 270 nm. Quantitative radial NO profiles obtained by LSF are presented and analyzed so as to correct similar LIF and PLIF profiles. Excellent agreement is achieved among the three fluorescence methodologies.

Effects of CH4 Content on NO Formation in One-Dimensional Adiabatic Flames Investigated by Saturated Laser-Induced Fluorescence and CHEMKIN Modeling

“…Laser scatter was avoided by shielding the laser path with black craft paper and a beam dump placed after the measurement zone. The NO mole fraction was measured with laser-saturated fluorescence (LSF) measurement as it is considered to be insensitive to both laser irradiance and the electronic quenching rate coefficients …”

“…The NO mole fraction was measured with laser-saturated fluorescence (LSF) measurement as it is considered to be insensitive to both laser irradiance 20 and the electronic quenching rate coefficients. 30 2.1.3. Signal Collection System.…”

Laser diagnostics for studies of turbulent combustion

“…The signal from saturated LIF is independent of collisional effects and the laser power, but saturation over the whole space and time of a measurement is not easy to achieve. A good discussion of saturation techniques with the example of NO is found in [101]; a comparison of linear and saturated techniques for quantitative and planar measurements is given in [25]. Usually one photon is used for excitation, but, with most atoms and some molecules (CO), only two-photon excitation schemes work.…”

Laser-induced fluorescence measurements in lean direct-injection spray flames: technique development and application

“…The magnitude of the un-scaled LIF measurements was ∼34% greater than that of the LSF measurements. Possible errors owing to the effects of RET dynamics on the LSF measurements are not sufficient to account for this deviation (Cooper et al 1998). We therefore invoked the more quantitative nature of the LSF measurements with respect to electronic quenching and presumed that they accurately represented NO concentrations in the LDI flame.…”

“…Some of these barriers include (1) spatial variations in the electronic quenching rate coefficient, (2) interferences from other species owing to broadband detection and (3) absorption of the laser sheet as it passes through the control volume. In an effort to make PLIF concentration images quantitative, Cooper et al (1998) developed a procedure whereby qualitative PLIF images in spray flames can be scaled to a single laser-saturated fluorescence (LSF) measurement so as to make the images quantitative within the error bars of the more accurate LSF point data. The quantitative nature of the LSF measurements arises from the fluorescence being nearly independent of both laser irradiance and the electronic quenching rate coefficient.…”