摘 要
隨著工業的發展與自動化的進步，真空技術的重要性日益增加，而各類真空幫浦中，噴射型真空產生器有著許多優點，因為其體積小、機構簡單、不易損毀、及產生真空方便，所以廣泛應用於自動化運送物品中；常見的運用在吸取外界空氣，或者接上吸盤吸取物件，特別適合於半導體製程、面板搬運、玻璃製造、家電製造等。本研究目標係針對噴射型真空產生器中，基礎的一段式真空產生器做性能優化，首先建立實驗設施以量測其性能參數，主要有空氣消耗量、最高吸入量、最大真空度這三項；接著運用CFD模擬來評估不同操作狀態下，其內部流場與壓力分佈的型態，並將模擬與實驗結果比對確認模擬之可信度。
在性能提升部分則藉助重要幾何參數的分析，透過改變主要噴嘴與混合排氣段之配合距離和混合排氣段直徑，並透過觀察其計算的流場與壓力分佈，評比分析出性能較佳的組合設計與噴流型態；其次依使用需求特性:高真空度和高吸入量，同時仔細考量對應的能源效率因子，分別選定合適的真空產生器之設計參數組合。最後藉由無因次分析方法針對一階段的真空產生器做推導，找出其對應的無因次函數式；接著將上述模擬所得數據取代實驗，據以找出實際之無因次關係式。此無因次關係式可用設計出不同尺寸的真空產生器，並可輕易計算出其預估的真空度、吸入量與能源效率，足以作為真空產生器設計之重要且易用的工具。

With the development of industry and the advancement of automation, the application of vacuum technology becomes more important to attract researcher’s attention. Among various vacuum pumps, the vacuum ejector owns many advantages, such as small size, simple structure, high durability, and easy to generate vacuum, so it is widely used in automated transportation and becomes the target of this thesis. The goal of this research is the performance enhancement of single-stage vacuum ejector, which can serve as the foundation for other complicate vacuum generators. An integrated effort of numerical, experimental, and dimensional-analysis technologies is constructed to attain several optimized ejector designs and an easy-to-use dimensional formular for industry engineers.
At first, the experimental facility is setup to measure the performance parameters (air consumption, maximum suction volume, and maximum vacuum pressure) of a commercial vacuum generator, Then, these test results are used to successfully validate the simulation outcome and CFD tool, which is utilized for executing the parametric study on key design variables of vacuum ejector. The variables considered here include gap between the main nozzle exit and the exhaust pipeline and the diameter of pipe. Thereafter, several appropriate parameter combinations of ejectors are selected to generate for fulfilling the demand of high vacuum pressure and large suction flow rate, respectively. Moreover, dimensional analysis is carried out on the vacuum generator to yield the corresponding nondimensional parameters and functional relations of suction flow rate and vacuum pressure. With the aids of CFD results, the actual function forms for these dimensional relations are decided with an accurate deviation. In conclusion, the accomplishment of this work provides a systematic design scheme for constructing the optimized vacuum generator to meet particular requirement in the practical applications. Also, the nondimensional formular offers a ready-to-use design tool for creating different sizes ejectors in a convenient manner.

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