| 摘要 |
PURPOSE:To make external oscillation and flow disturbance hard to exert influence by specifying the shapes and sizes of a vortex generation body and a detection pipe. CONSTITUTION:The detection pipe 28 of the vortex generation body 16 increases in sensitivity with its external diameter, but such a gap that the tube 28 does not contact the internal wall of a cavity part 24 is required to detect the strain of the pipe 28. The gap 26 needs to be determined so that there is no influence of foreign matter in fluid. For the purpose, the shapes and sizes of the generation body 16 and pipe 28 are specified to accelerate the flow at the periphery of the generation body 16 and the generate Karman's vortex streets behind the generation body 16. Then, pressure difference of the fluid generated between both flanks 42R and 42L of the generation body 16 operates on the pipe 28 as differential pressure to generate flexural stress, whose variation is detected by a magnetostrictive element. In this case, slits 44R and 44L are made long to improve linearity and then the Karman's vortex streets are generated stably even if the fluid to be measured is disordered owing to a drift current and a swivel current. Further, one end of the pipe 28 is formed cylindrically to increase the natural frequency, thereby reducing the influence of external oscillation. |
