초록 ▼

Instead of providing a channel in a Pitot tube for measuring static pressure, a channel is provided which terminates in an orifice facing perpendicular to the direction of the flow to be measured, surrounded by a rim having a surface, which may be quite narrow, that is inclined at between 15°and 45°

Instead of providing a channel in a Pitot tube for measuring static pressure, a channel is provided which terminates in an orifice facing perpendicular to the direction of the flow to be measured, surrounded by a rim having a surface, which may be quite narrow, that is inclined at between 15°and 45°, preferably 30°, to the plane perpendicular to the axis of the orifice, in order to intensify somewhat the Bernouilli effect of the flow across the orifice. This produces a suction (reduction of pressure) approximately equal to the increase of pressure sensed at an upstream facing orifice of a second channel produced by the same flow which is being measured. A differential manometer connected to the two channels registers about twice the pressure difference that would be measured between the pressure at an upstream facing orifice and the pressure in a channel that measures merely the static pressure in the flowing medium.

대표청구항 ▼

Double-acting differential fluid pressure measuring device for measuring fluid flow, comprising: a dual-channel elongate duct equipped for mounting in a position transverse to the direction of flow of a fluid medium into which a portion of said duct, including a first end thereof, projects when moun

Double-acting differential fluid pressure measuring device for measuring fluid flow, comprising: a dual-channel elongate duct equipped for mounting in a position transverse to the direction of flow of a fluid medium into which a portion of said duct, including a first end thereof, projects when mounted in said position, said mounted position defining an upstream side of said portion of said duct, said duct having a first channel, having straight end portion, for measuring a pressure lower than the static pressure of said medium when there is a flow of said medium in said direction and a second channel for measuring a pressure higher than the static pressure of said medium when there is a flow of said medium in said direction; a first orifice at said first end of said duct providing an open end for said straight end portion of said first channel facing perpendicularly to said direction of flow and terminating in a plane perpendicular to said straight end portion of said first channel, for passage of said fluid medium into and out of said first channel, said first orifice being provided with a fluid-deflecting rim surrounding said first orifice having a surface inclined to said plane perpendicular to said straight end portion of said first channel, said inclined surface having a central profile, in said direction of flow, inclined at an angle to said plane, averaged along said profile leading away from said plane to the outer periphery of said surface which is in the range from 15°to 45°; a second orifice on said upstream side of said duct near said first end thereof for permitting passage of said fluid medium into and out of said second channel; means at and near a second end of said duct, oppositely located relative to said first end, for connecting said first channel of said duct to the low-pressure sensing connection of a differential manometer having high and low pressure sensing connections and for connecting said second channel of said duct to the high pressure sensing connection of said differential manometer; whereby said manometer, by virtue of the position of said first orifice and the configuration and extent of said rim, measures a pressure difference representative of the rate of said flow which difference is at least 25% greater than the difference between the pressure at said high pressure sensing connection of said manometer and the static pressure of said medium in the region of the measure flow.