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

Abstract

The combustion diagnostics community has recently begun to focus its efforts toward practical combustion devices. One impetus behind this effort is the need to develop aeropropulsion gas turbine combustors with ultra-low NOx emissions. For the past several years, the Flame Diagnostics Laboratory at Purdue University has been advancing optically non-intrusive techniques to measure concentrations of nitric oxide [NO] in lean direct-injection (LDI) spray flames. LDI flames offer the possibility of reducing NOx emissions from gas turbines by rapid mixing of the liquid fuel and air so as to drive the flame structure toward partially premixed conditions. In this paper, we review the technical approach required to utilize laser-induced fluorescence (LIF) methods for quantitatively measuring [NO] in LDI spray flames. In the progression from atmospheric to high-pressure measurements, the LIF method requires a shift from the saturated to the linear regime of fluorescence measurements. As such, we discuss quantitative, spatially resolved laser-saturated fluorescence (LSF), linear laser-induced fluorescence (LIF) and planar laser-induced fluorescence (PLIF) measurements of NO concentration in atmospheric, LDI spray flames. In general, the results are comparable, although novel filtering techniques are required at higher flame pressures.

Mixing intensification by chaotic advection inside droplets for controlled nanoparticle preparation

“…This technique has been successfully used in many studies of mixing process (Cooper and Laurendeau 2000;Gordon et al 2004;Liu et al 2008;Liu et al 2009;Luo et al 2006;Luo et al 2007;Nere et al 2003;Pan and Meng 2001;Thurber and Hanson 2001).…”

Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames III Comparison of A–X excitation schemes

“…60 Narrowband monochromator detection ͑Ͻ5-nm bandpass͒ was used in most of the research for effective interference suppression; however, significant interference was observed with broadband imaging detection in the 4-bar spray flame. 55,61 In previous research, we investigated different transitions within the A-X͑0, 0͒ band in detail in premixed flat CH 4 -air flames up to 60 bar and discussed their applicability for high-pressure combustion situations. 4 It was shown that the transition originally proposed by DiRosa et al 24 is clearly superior to other approaches in terms of both signal strength and suppression of O 2 LIF interference.…”

Measurement of gas concentration by wavelength shift method with an EDFA fiber laser loop

“…The sensitivity, therefore, is limited. Alternatively, other spectroscopy techniques based on the detection of absorption induced phenomena of light can be used such as pressure changes in photoacoustic spectroscopy [6], laser-induced fluorescence (LIF) [7,8], or ions in resonant enhanced multiphoton ionization (REMPI) [9]. But they are hard to calibrate.…”