高轉速下光學反射鏡之流場數值分析與系統設計

Airflow Numerical Simulation and System Design of High-speed Rotating Reflector

蕭詠中(Yung-Chung Hsiao)

指導教授 ： 楊宏智

國立臺灣大學/工學院/機械工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10218

摘要

本研究針對在高速轉動下的光學反射鏡，在不改變驅動主軸的狀況下，期望能以降低風阻的方式，來提高反射鏡所能達到的最高轉速。為了了解風阻與外型關係，我們使用流場模擬，找出最佳的反射鏡外型設計以及風罩外型。在30000 rpm的轉速下，得出最佳的反射鏡外型，其外型為使用圓角的兩面鏡，並加裝圓盤構造，圓盤半徑為1.1倍兩面鏡半徑，高度為2 mm，所受到的風阻扭矩為0.037 N-m，比起目前所使用兩面鏡 0.078 N-m的還低，大幅降低了約52%的風阻。風罩參數方面，考慮到成本因素，最佳之風罩外型參數，是風罩內徑為1.3倍兩面鏡半徑，風罩高度為1.4倍的兩面鏡高度，此時所受到的風阻扭矩約為0.039 N-m。而在不考慮成本因素狀況下，風罩內徑可選擇2.4倍以上的兩面鏡半徑，風罩高度可選擇1.4倍以上的兩面鏡高度。
新主軸反射鏡系統使用倒立設計，輕量化改良後不但重量輕，方便搬運，也可以將反射鏡調整至適當的高度，以符合光學系統需求，運轉也沒有問題。使用旋轉微調裝置，可以幫助我們更方便且快速的校正光路。然而，油氣問題以及兩面鏡夾持變形問題，是未來必須解決的目標。

關鍵字

旋轉反射鏡 ； 高速轉動 ； 計算流體力學 ； 風阻扭矩

並列摘要

This thesis aims at increasing the peak rotating speed of the high-speed optical reflectors without altering the driving spindle by reducing associated windage. In order to determine the relationship between windage and the shape of the optical reflectors, airflow simulations were used to find the best shape design of the reflector and the cover. At 30000 rpm, the best shape of the reflector is the two-faceted mirror with round corner and added disks whose radius is 1.1 times radius of the two-faceted mirror and thickness is 2 mm. The windage torque for the new designed reflectors, 0.037 N-m, is lower than the windage torque, 0.078 N-m, for the traditional ones. It decreases about 52% windage torque. Without much increasing the cost, the best shape parameter of the cover is that the cover radius is 1.3 times of the two-faceted mirror, the cover height is 1.4 times of the two-faceted mirror, while the windage torque is about 0.039 N-m. Regardless of the cost, above 2.4 times radius and above 1.4 times height of the two-faceted mirror is selected preferred.
The reflector system of new spindle uses the design of handstand. After redesigning to reduce the weight, it is convenient to move this system. For the optical system, reflector can be adjusted to the proper altitude. The reflector system can work. By using the precision rotary device, it is convenient and quickly to adjust the optical beams. However, it is necessary to solve the oil-air problem and the deformation problem caused by clipping the two-faceted mirror in the future.

並列關鍵字

rotating reflector ； high-speed rotating ； CFD ； windage torque

參考文獻

[10] 張哲源,“高轉速下光學反射鏡之製程與加工研究,” 國立台灣大學工學院機械工程學系碩士論文, 2008

[5] Frank M. White, “Fluid Mechanics 5th,” McGraw-Hill, 2003

[6] FLUENT6.1 Documentation, Fluent Inc.

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[2] Willian T.Moore, “Optical scanning system with compensation for unwanted image rotation during scanner,” US Patent, No. 4,202,597, 1980