單直管科氏質量流量計之理論建構與模擬

本論文主要的目標在於合理的假設條件下，建立一個較為簡單的數學模型，透過此模型來探討單直管CMF的運作行為，並且探討各種設計參數對於單直管CMF運作中的影響。除此之外，針對感測器以及微調質量等質量塊的安裝位置找出最佳位置點，並使用相關研究成果協助產業開發單直管CMF的產品。首先，本論文提出針對單直管CMF的振動行為數學模型，再透過MATLAB作進一步的驗證，計算出單直管CMF的自然振動頻率以及振動行為，同時也可以得到每種不同的單直管CMF的量測靈敏度以及量測時間差。此外，本論文亦提出使用最佳化方法計算出感測器以及微調質量的最佳安裝位置。最後，本論文也針對各種設計參數作討論，找出在設計過程中，最主要影響單直管CMF量測表現的影響因子，有助於產業開發設計單直管CMF時可以作為參考。最後，透過ANSYS模擬來驗證理論計算的結果，使用流固耦合的模型進行計算，成功計算並驗證各種不同模型的自然振動頻率、量測時間差以及質量流量等性能指標。以自然振動頻率為例，兩種不同的設計模型與理論的計算結果誤差仍在3 %以內。然而，在量測時間差的誤差相較於自然振動頻率的結果稍大一些，但是在趨勢上仍與理論非常吻合，模擬結果仍可以做為未來結果比較參考的依據。

關鍵字

科氏質量流量計；量測點最佳化；流固耦合模擬；模態展開

並列摘要

In this research, we constructed a simple mathematical modal to describe the operation of single tube Coriolis mass flowmeter (CMF) with the suitable conditions and discuss some related issues including looking for the optimal positions of sensors, adjust mass and the dominant design factors of single tube CMF. These contribution would assist the cooperator to develop the related products. First of all, we utilized modal expansion method to solve the equation of motion for single tube CMF and verify our mathematical modal by MATLAB algorithms. Secondly, we could obtain natural frequency and displacement of vibrating tube from our mathematical modal. After that sensitivity of single tube CMF and measure time difference could be calculated. Thirdly, global optimization was applied for the sensor position, adjust mass position so that we could get the maximum sensitivity. Furthermore, the dominant design factors were found out that would help for constructing our own experimental facility in the future. Finally, in order to compare the results between ANSYS and MATLAB, we set up a fluid structure interaction simulation model, calculate the natural frequency and measure time difference successfully.

並列關鍵字

Coriolis Mass Flowmeter ； Optimal Position of Sensor ； Fluid Structure Interaction ； Modal Expansion Method

參考文獻

[1] P. Kollsman, “Apparatus for Measuring Weight Flow of Fluids,” U.S. Patent, 2602330, July 1952.

[7] N. M. Keita, “Contribution to the Understanding of the Zero Shift Effects in Coriolis Mass Flowmeters,” Flow Measurement and Instrumentation, Vol. 1, pp. 39–43, October 1989.

[9] G. Sultan, “Single Straight-Tube Coriolis Mass Flowmeter,” Flow Measurement and Instrumentation, Vol. 3, pp. 241–246, October 1992.

[10] R. Cheesewright and C. Clark, “The Effect of Flow Pulsations on Coriolis Mass Flow Meters,” Journal of Fluids and Structures, Vol. 12, pp. 1025–1039, November 1998.

[11] A. Belhadj, R. Cheesewright, and C. Clark, “The Simulation of Coriolis Meter Respones to Pulsation Flow Using a General Purpose F. E. Code,” Journal of Fluids and Structures, Vol. 14, pp. 613–634, July 2000.

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單直管科氏質量流量計之理論建構與模擬

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