Temperature and Density Measurements in an Engine by Pulsed Raman Spectroscopy

Abstract

<div class="htmlview paragraph">Measurements of temperature and nitrogen density and the fluctuations of these quantities have been made in a combusting engine. The measurements were made by applying pulsed, spontaneous laser Raman spectroscopy. This nonintrusive technique demonstrates one cubic millimeter spatial resolution and essentially instantaneous temporal resolution (10<sup>−8</sup> second). Densities were determined by measuring the Stokes vibrational scattering of nitrogen, and the temperatures were determined by measuring the ratio of anti-Stokes to Stokes scattering. The diagnostic technique is described and its accuracy analyzed.</div> <div class="htmlview paragraph">Temperatures and densities at two locations, over crank angles covering the compression and expansion strokes, for four equivalence ratios are presented. Typical temperature probability distributions are also presented.</div>