Image Number 6 for United States Patent #4680962.
A fluid flow measuring device which does not disturb the fluid flow, in one embodiment is responsive to flow in each of three orthogonal directions. A central electrode carrying ionizing needle electrodes is combined with a concentric and coaxial open ion collecting structure that establishes a voltage gradient to the central electrode. The preferred embodiment employs a plurality of rings supported by rods that are parallel to the central electrode. The rings are subdivided into quadrants by insulating segments. Displacement of the ion cloud, resulting from fluid motion, is directly related to fluid velocity and can be resolved into components in the desired directions. Alternative embodiments include cylindrical sensors that can be oriented in the fluid stream for non interference with the rate and direction of flow.