Passive Optical Measurement of Velocity in a Luminous Flow

A segmented-image emission velocimeter (SIEVE) is an optical instrument for measuring the velocity of a luminous turbulent flow. More specifically, it measures a component of flow velocity perpendicular to its line of sight. This instrument is not only nonintrusive but is also passive in the sense that unlike other flow-measuring optical instruments, it does not seed the flow and does not illuminate the flow to obtain scattering of light from seed particles in the flow; instead, it utilizes broad-band light emitted by the flow. Flows amenable to SIEVE velocity measurement include flames and rocket exhaust plumes.