Soot size measurement in a swirl stratified flame using high-speed angular light scattering

Abstract

Soot size measurement in a swirl stratified flame using high-speed angular light scattering RESUME Les travaux presentes dans cette etude concernent des mesures de tailles de particules de suie produites lors de la combustion de l ethylene. La flamme etudiee est representative des conditions aeronautiques, c est-adire turbulente, stratifiee (fort gradient spatial de richesse) et swirlee (ecoulement rotatif). La diffusion elastique de la lumiere est utilisee afin de determiner la taille des particules de suie. Cette technique est appliquee ici dans un plan a l aide d une nappe laser ainsi que de trois cameras disposees a trois angles de diffusion differents. En effet, l intensite de la lumiere diffusee, resultante de l interaction entre un faisceau laser et l aerosol, varie en fonction de l angle auquel on collecte le signal. Cette variation angulaire est une signature de la taille des particules etudiees. Puisque la flamme etudiee est turbulente donc instationnaire, des cameras haute-cadence sont utilisees permettant un suivi dynamique de la taille des particules dans la flamme. ABSTRACT The present study concerns size measurement of soot particles which are produced during the combustion of ethylene. The flame which is studied is representative of aeronautic conditions, i.e. turbulent, stratified (high spatial equivalence ratio gradient) and swirled (rotating flow). Elastic light scattering is used in order to determine the soot particle size. This technique is applied in planar configuration thanks to a laser sheet and three cameras placed at three different scattering angles. Indeed, the intensity of the scattered light, which results from the interaction of the laser with the particles, varies with the angle at which the signal is collected. This angular variation allows a determination of the particle size. Because the flame under study is turbulent, high-speed cameras are used in order to enable a temporal tracking of the particles size in the flame.