多噴射流水流量計之流體結構耦合分析與參數化設計

Abstract

本研究透過流體結構耦合數值模擬方法，深入分析多噴射流水流量計的內部流場與葉輪轉動行為，並建立了一套有效的參數化設計流程。隨著智慧水務與即時監控需求的增加，多噴射流水流量計因其結構簡單、成本低廉，以及在低流量下具備良好的靈敏性與穩定性，已成為住宅及小型商業用戶流量計量的重要工具。然而，實務上水流量計於不同流量條件下的轉動響應具非線性特性，導致產品校正流程繁瑣且成本高昂。因此，本研究透過模擬輔助設計，期望能有效提升水流量計性能，簡化校正流程。 本研究首先透過實驗測試現有商用多噴射流水流量計之性能，並採用計算流體力學軟體COMSOL進行有限元素法數值模擬，以驗證所建模型之可靠性與準確性。進一步分析不同葉輪桶孔數配置對水流量計性能的影響。模擬結果顯示，減少葉輪桶入口孔數可有效提升低流量區的啟動靈敏度，且對高流量條件下的性能及壓降影響有限。其中，「8-1孔」設計尤其能避免射流直接衝擊葉輪中心所導致的不穩定推力，有效兼顧流場穩定性與計量靈敏度，整體性能具明顯改善，但模擬結果亦顯示，不同流量下的計量常數 𝐾𝑚 值仍存在變化，指出在實現全面線性化方面仍有優化空間。 本研究成果證實數值模擬方法在水流量計設計階段的有效性，有助於縮短產品開發與測試週期，提供未來多噴射流水流量計實務設計的參考基礎，並協助產業在生產效率與產品性能穩定性間取得更佳平衡。

The advancement of smart water management systems requires water meters capable of real-time monitoring, accurate measurement, and cost efficiency. Among various options, multi-jet water meters have become prevalent in residential and small commercial applications due to their simple structure, low cost, and excellent sensitivity and stability at low flow rates. However, their non-linear rotational response under varying flow conditions complicates the calibration process, thus increasing production complexity and cost. To address this issue, this study utilizes fluid-structure interaction numerical simulation methods to analyze internal flow characteristics and impeller rotational behavior of multi-jet water meters, aiming to simplify product design and calibration processes. This research first validates the reliability of the numerical model by conducting experimental tests on commercial multi-jet water meters, and then performs finite element simulations using the computational fluid dynamics software COMSOL to ensure the model’s accuracy. The study further investigates the impact of different impeller chamber inlet configurations on water meter performance. Simulation results indicate that reducing the number of inlet holes significantly enhances startup sensitivity at low flow rates, with minimal impact on performance and pressure drop at higher flow rates. Notably, the “8-1 hole” design effectively prevents unstable thrust caused by jet streams directly impacting the impeller center, thereby improving both flow stability and measurement sensitivity. While these design changes improved low-flow sensitivity, simulations also revealed that the 𝐾𝑚 value still exhibited variations across different flow rates, suggesting that further optimization is needed to achieve ideal calibration linearity.