此研究運用直接數值模擬（DNS）方法，進行牙科高速氣動渦輪手機空轉運作時之流場模擬，深入探討在相同入口氣壓及轉子轉速的條件下，不同設計轉子其壓力分布變化、運作性能與氣動噪音特性。在研究中，我們採用合適於大規模平行計算的正交網格結構，且結合沉浸邊界法（IBM）來處理轉子的複雜幾何形狀，針對修改轉子之葉輪設計，並對其8片葉片編號，透過觀察其各自的正向受力面與背向受力面之壓力差與總壓力差，研究轉子扭矩以及使用快速傅立葉轉換（FFT）將壓力數值轉換成頻率與分貝數，探討對聲音的影響。在最後章節，本文根據不同轉子設計模擬之分析結果條列出以下結論。
本文通過比較不同葉輪設計之模擬結果，探討了形狀優化之可能性，期望能透過改變葉輪形狀來降低氣動噪音，提升醫者與病患對牙科治療的舒適度與效率。研究表明，轉子在高速旋轉時，位於氣動渦輪手機氣壓入口處和出口處的葉輪葉片為不同轉子設計下，壓力差結果變化最大之處。其中，增加氣壓推動時正向受力面之表面積，可提升正向與背向之壓力差，加強其扭矩值，幫助牙科高速氣動渦輪手機維持良好運轉與性能運作，但容易提高氣動噪音分貝數上升之可能性；相對而言，若嘗試在背向受力面形成圓角，使正向受力面的氣壓較不直接過渡至背向受力面，降低其壓力差值，則可有效降低氣動渦輪手機運轉時帶來的噪音，但會使牙科高速氣動渦輪手機運作性能較為減弱。最終進行各自設計之結果比對，選擇在葉輪每片葉片的背向受力面形成較小的圓角的設計，雖扭矩值降低了一些，但仍在合理範圍中，並幾乎不影響氣動渦輪手機之性能運轉，且對於降低氣動噪音有顯著的效果。

This study utilizes Direct Numerical Simulation (DNS) to investigate the internal flow dynamics of a dental high-speed air turbine handpiece during idle operation. Under con-sistent inlet pressure and rotor speed, the aerodynamic performance, pressure distribution, and aeroacoustic characteristics of rotors with different designs were analyzed.
A structured orthogonal grid suitable for large-scale parallel computing was used in con-junction with the Immersed Boundary Method (IBM) to handle the complex rotor geometry. The impeller design was modified, and its eight blades were numbered to allow de-tailed observation of the pressure difference between the pressure and suction surfaces of each blade, as well as the total pressure drop. The resulting pressure data were transformed using Fast Fourier Transform (FFT) to evaluate the corresponding frequency and sound pressure levels.
Comparative analysis of simulation results revealed that changes near the inlet and outlet of the rotor induce the greatest variation in pressure differences. Increasing the area of the pressure surface improves torque output but also tends to increase aeroacoustic noise. In contrast, incorporating fillets on the suction surface can reduce noise by decreasing the pressure difference, albeit with a slight reduction in performance. Among the designs tested, a rotor with a small fillet on each blade's suction side achieved effective noise reduction with minimal compromise in torque, demonstrating a promising approach for optimizing the balance between performance and noise in dental handpieces.

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