Particle deposition in a burner

The flame deposition of colloidal silica particles onto a collector has been characterized for a simple, cylindrically symmetric geometry. Material is deposited over a limited area of a disk and the individual particle paths form an inverted cone which can be observed to penetrate the boundary layer at the disk surface. The paths emanate from a narrow stream confined close to the axis of the flow. A model is proposed to qualitatively explain the collection process and account for observed behavior. This comparatively simple approach apparently contains the essential features of the process. The general form of the deposition is determined by inertial forces on the particles. Impaction, however, is due to forces which result from moderate thermal gradients near the collector surface. A critical radius exists, depending upon conditions of temperature and flow, beyond which deposition does not occur. Although the model provides a generally unsatisfactory description of the flux distribution, it is apparent that the flux will be a maximum off center, resulting in a depression in the center of the collected material. Deposition at the stagnation point is a special case, beyond the scope of this model.