Abstract: According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.

Abstract: A separation plate (10) includes a first surface and an opposing second surface. Plural pairs of a nozzle (14) and a virtual impactor (16) are provided on the first surface. Each nozzle tapers from an inlet end (14a) to an outlet end (14b). Each virtual impactor comprises a pair of generally fin-shaped projections (24). Each fin-shaped projection includes an inner wall (26) and a convex outer wall (28). The inner walls of the fin-shaped projections of a virtual impactor face each other to define a minor flow passage (30) therebetween. The convex outer walls of the fin-shaped projections of a virtual impactor cooperatively present a convex surface including a virtual impact void therethrough. The virtual impact void defines an inlet end of the minor flow passage. A virtual impactor body (33) is provided between adjacent virtual impactors (16).