- 學位論文
真空氣動梭鼓風機音場分析與降噪設計
Acoustic Analysis and Noise Reduction Design of Blowers for Pneumatic Vacuum Elevators
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摘要
真空氣動梭(PVE，Pneumatic Vacuum Elevator)是一種創新型電梯，欲上樓時由抽氣設備產生電梯車廂上下壓差推動車廂上升；欲下樓時利用重力自然下降節省能源。本產品突破傳統電梯之限制，毋需建造機房、升降道和底坑，大幅節省空間，非常適合已完成之公寓或樓中樓等未規劃電梯空間之建築物，具龐大商機。然而，目前仍不普及之一大主因，源於電梯上行時，產生令人不適之噪音。 本研究針對真空氣動梭之噪音問題，提出一套有效降噪方法，除確立噪音源外，透過文獻回顧評估各類降噪手段，並以電腦輔助工程分析CFD（Computational Fluid Dynamics，計算流體力學）軟體FLUENT，建立可預測噪音之虛擬原型，藉此觀察流場、聲場之變化，提出改良策略加以討論。 歸納模擬結果，可發現設計抗性膨脹室消音器之幾何形狀，可有效降低真空氣動梭之噪音。並分析各種吸音材料對於不同頻率噪音之吸聲性能，針對本研究之噪音源進行阻抗複合型消音器之設計。實測方面，則利用小型無音箱、噪音計搭配閃頻儀（量測鼓風機葉輪轉速）進行噪音量測。 掌握以上降噪設計策略，針對PVE噪音問題設計改良之成效良好：加裝消音器後，噪音降低4.8分貝，而流體動力性能不減；再加裝外覆防音材（聚氨酯棉），可再度降低噪音2.7分貝，總共降低7.5分貝，證實本研究之設計方法可有效降低產品噪音。 關鍵字：真空氣動梭、電梯、抽氣設備、噪音、計算流體力學、消音器
並列摘要
We present Pneumatic Vacuum Elevator (PVE), a novel elevator technology reducing energy consumptions by driving the elevator with air pressure. An air pumping equipment increases the air pressure to pulls the cabin and carries passengers upward; releases the air pressure while the gravity drops the cabin downward slowly. Comparing to the conventional elevators, the presented product is much more space-saving considering the construction of the machine room, since the hoist way or pit are no longer necessary for the system. PVE offers enormous potential business opportunities because of its suitability for completed condominium or duplex apartments, which have no reserved space for elevators. However, the PVE is not generally adopted nowadays because of producing noise when vacuuming the elevator cabin upward. The goal of our research is to reduce the noise effectively. First, we identify the source of noise. Second, we evaluate the existing noise reducing methods. By using computer aided engineering and computational fluid dynamics (CFD) software, FLUENT, we then conduct a noise- predictable virtual model to observe the dynamic of the flow/sound fields. Finally, we propose a solution and strategies for further improvement. Base on the analysis result, the geometry of the reactive expansion chambers mufflers would affect the noise produced in the vacuuming process. Therefore, we research the shape of the mufflers and exam several sound-absorbing materials for noise absorption properties under different frequencies, and design a hybrid muffler for the specific noise source. To exam the prototype, we design a series of experiments to measure noise using a small anechoic tank, a sound level meter and a digital stroboscope (especially for measuring RPM of the blade). This approach provides an efficient noise reducing solution for PVE. After conducting noise control design strategies and implementations mentioned above, the noise is decreased by 4.8 dB without affecting required fluid dynamics performance. By adding additional covers made with polyurethane cotton, a sound soundproof material, to the device, the noise is decreased by 2.7 dB more, which leads to 7.5 dB decreasing in total. To summarize, this result demonstrates our design effectively reduces the noise from the product. Keywords: Pneumatic Vacuum Elevator (PVE), elevators, pumping equipments, noise, computational fluid dynamics (CFD), muffler
參考文獻
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