Signal quality analysis of a vortex flowmeter downstream of two 90 degree elbows out-of-plane
| Autor: | Chen-Wen Wu, 巫清文 |
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| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 The purpose of this work is to examine why the signal quality of a vortex flowmeter obtained at 15D downstream of two 90 degree out-of-plane elbows superior to that obtained at other locations downstream of the elbows. The vortex flowmeter employed is of 2 inch（50mm）in diameter and the vortex frequency sensor employed is of piezo electric type. The working fluid is water. Base on the diameter of the pipe and the bulk velocity of the pipe flow, the Reynolds numbers achieved in the experiments are in a range of 5×104 ~ 3×105. For the present pipe flow facility, flow reaches the fully-developed state at 45D downstream from the contraction. Subsequently the two 90 degree out-of-plane elbows is placed downstream of 45D from the contraction. It is noticed that the vortex flowmeter located at 15D dowmstream of elbows, shows the signal quality superior to that obtained at the other downstream locations. Measurements results obtained from a cobra probe show that a clockwise swirling flow structure develops downstream two 90 degree out-of-plane elbows, whose axial velocity distribution obtained at 15D downstream is more uniform than those obtained at other locations. Based on the present results obtained a suggestion is that the superiority of the vortex shedding signal quality obtained at 15D downstream is due to the uniformity of the axial velocity distribution, the effect of swirling appears less important. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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