New approach to single‐shot CARS thermometry of high‐pressure, high‐temperature hydrocarbon flames

Abstract

We demonstrate the feasibility of a proposed new approach to CARS thermometry with simultaneous measurements of the intensities of the hydrogen Q-branch lines and their linewidths during a single laser shot by means of a spectrograph combined with an interferometer having orthogonal directions of dispersions. This allows correct temperature evaluation that takes into account the directly measured linewidths. The experiments were carried out in a H 2 : N 2 = 1 : 10 mixture in a heated cell at a temperature of 1050 K. The values of the gas mixture temperature, which were defined from dual-broad band (DBB) CARS spectra with linewidth corrections in a pressure range of 2-9 MPa, coincide with thermocouple measurements within ∼2%, while without such a correction, the discrepancies increase up to 5%. The proposed approach can be applied to CARS temperature measurements in investigations of H 2 and hydrocarbon combustions without the necessity of species concentration measurements and not requiring the knowledge of line-broadening coefficients.

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

“…[143][144][145] Clauss and collaborators applied hydrogen CARS thermometry to combustion systems of relevance to rocket engines. For example, they studied cryogenic liquid oxygen (LOX) and gaseous oxygen-fed hydrogen [146][147][148] and hydrocarbon 147,149,150 flames operated under rather extreme conditions, i.e., pressures as high as 20 MPa and temperatures as high as 3000 K. Similar temperatures were measured in the jet flame of a staged oxy-fuel burner of a large-scale industrial furnace fueled with natural gas. 151 Kampmann et al 152 used vibrational CARS in a highly turbulent swirl flame.…”

Recent advances in linear and nonlinear Raman spectroscopy II

“…A three-laser, dual-pump CARS technique for the simultaneous detection of nitrogen, carbon monoxide and hydrogen has been developed and tested by Weikl et al 52 Measurements, which were in good agreement with theoretical spectral calculations, were taken in a heated cell and in a partially premixed propane/air flame. Fabelinsky et al 53 demonstrated the feasibility of a proposed new approach to single-shot CARS thermometry of highpressure and high-temperature hydrocarbon flames. The intensities of hydrogen Q-branch lines and their linewidths during a single laser shot were measured by means of a spectrograph combined with an interferometer having orthogonal directions of dispersions.…”

Single‐shot CARS thermometry of high‐pressure hydrocarbon flames using simultaneous intensity and linewidth measurements

“…[5] The idea is the simultaneous measurements of hydrogen Q-branch line intensities and their linewidths with the help of a spectrometer and an interferometer having orthogonal dispersions. In such an approach, the information on linewidths obtained from a single-shot CARS spectrum is directly used in temperature evaluation routines and does not require any knowledge of species concentration and broadening coefficients for a multispecies mixture.…”