Fluid flow measuring device |
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| 申请号 | US3785206D | 申请日 | 1972-04-26 | 公开(公告)号 | US3785206A | 公开(公告)日 | 1974-01-15 |
| 申请人 | TELEDYNE INC; | 发明人 | BENSON J; BAKER W; | ||||
| 摘要 | Apparatus for measuring the velocity of fluid flow includes a form of pitot tube having orifices that develop a differential pressure related to the stream velocity and a means of directing an auxiliary stream of gas at or near one of the orifices. The auxiliary stream is arranged to be deflected by the main stream so that in the range of low velocities of the main stream, wherein pitot tubes are insensitive, the sensitivity of the apparatus is enhanced. In a preferred form of the device, a purged thermal flowmeter connected to the two orifices senses the velocity of the main stream. | ||||||
| 权利要求 | 1. Apparatus for measuring fluid flow through a supply line, compriSing: a. means including a pair of orifices within said line for developing a differential pressure thereacross in response to flow through the supply line; b. a shunt path bridging said orifices; c. a flowmeter connected to said shunt path; d. means for supplying purging fluid to said shunt path at points on opposite sides of the flowmeter; and e. means for amplifying the differential pressure developed by said developing means only when there is fluid flow through said supply line below a predetermined level, said amplifying means including means for introducing said purging fluid into the supply line in relationship to said orifices such that said purging fluid is directed at one of said orifices only when there is fluid flow through the supply line below said predetermined level. 2. Apparatus for measuring fluid flow as set forth in claim 1, wherein said differential pressure developing means comprises a pitot tube and wherein the amplifying means includes an auxiliary jet of purging fluid introduced into said supply line upstream of the pitot tube. 3. Apparatus for measuring fluid flow as set forth in claim 2, further comprising an additional auxiliary jet of fluid introduced into said supply line downstream of the pitot tube to permit apparatus to function when the direction of fluid flow in the supply line is reversed. 4. Apparatus for measuring fluid flow as set forth in claim 1, wherein said purging fluid is supplied to the shunt path at a pressure greater than that at either orifice whereby contact between the fluid in the supply line and the flowmeter is prevented. 5. Apparatus for measuring fluid flow as set forth in claim 4, wherein said differential pressure developing means comprises a pitot tube and wherein the amplifying means includes an auxiliary jet of purging fluid introduced into said supply line normal to the path of flow in the supply line and directed towards the downstream orifice of the pitot tube. 6. Apparatus for measuring fluid flow as set forth in claim 1, wherein said differential pressure developing means comprises a pitot tube having its orifices in facing relationship and wherein the purging fluid is supplied to the shunt path at a pressure greater than that at either orifice so as to cause purging fluid to issue from of said orifices. 7. Apparatus for measuring fluid flow as set forth in claim 6, wherein said orifices are in alignment along an axis normal to the direction of fluid flow in the supply line. 8. Apparatus for measuring fluid flow as set forth in claim 6, wherein the axes of said orifices define a plane extending in the direction of fluid flow in the supply line. |
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