Quantitative oxygen imaging in an engine

Abstract

Simultaneous imaging of laser-induced fluorescence of toluene and 3-pentanone was used to determine the local absolute oxygen and residual gas concentrations present within an engine. The technique utilizes the different sensitivities of the laser-excited molecules to quenching by molecular oxygen as a means to determine quantitative images of in-cylinder oxygen concentrations. The difference in the amount of oxygen available between two operating conditions was investigated. Results are in agreement with measurements in the exhaust gas.

Absorption and fluorescence of toluene vapor at elevated temperatures

“…13 Adding an additional tracer that is oxygeninsensitive enables the simultaneous quantification of fuel and oxygen concentrations. 14,15 Despite the frequent application of toluene for fuel concentration diagnostics in the mixing and compression phase of internal combustion engines, no information is available about the variation of absorption crosssections and fluorescence quantum yields in the relevant pressure and temperature range. As a result, many authors simply assume negligible pressure and temperature effects.…”

Thermally-excited fluorescence of strontium products for in-cylinder temperature diagnostics in internal combustion engines

“…Using early fuel injection strategies accomplishes this for the present engine. 39,40 Charge homogeneity also allowed for a 1-D thermodynamic model of the engine, described below, to give adequate temperature calculations for the burned gas region since it uses a two-zone combustion submodel. Repeatability of results and minimization of cycle-to-cycle variation was sought to allow averaging of spectra for the calibration step of the procedure.…”

Diffractive/refractive (hybrid) UV-imaging system for minimally invasive metrology: design, performance, and application experiments

“…The tracers also are very different in terms of their collisional, nonradiative de-excitation (quenching): While toluene is very efficiently quenched by oxygen, 3-pentanone is nearly independent on the oxygen partial pressure. Detecting LIF from both tracers simultaneously in two detection channels, the oxygen partial pressure can be determined [29], which is of particular interest in modern engine operating strategies. It is also possible to evaluate the local temperature exploiting a red shift of toluene's emission spectrum.…”