本研究主要目的為量測低雷諾數下，平面微擴流器的損失係數隨擴張角之變化。實驗用的平面微擴流器之細長比為15，擴張角由 - ，雷諾數範圍由100-2000。本研究之實驗架構：由一個程式控制的精密注射幫浦，推動針筒，使流體通過一段管路系統，注入儲液槽後，再通過微擴流器，進入水槽。儲液槽的壓力是以已校正的精密壓力感測器來量測，並將量測到的壓力代入損失係數關係式，計算微擴流器的損失係數。透過實驗結果，我們發現不論是小角度或大角度，損失係數都會隨著雷諾數的減少而增加。在小角度的時候，微擴流器受到黏滯摩擦損失的影響，會產生很大的損失係數，甚至比大角度的損失係數更大；在大角度的時候，微擴流器的壓力損失主要是由流場分離產生，受到黏滯摩擦損失的影響有限。

This study aims at measuring the loss coefficients of planar microdiffusers under low Reynolds number flow as a function of divergence angle. The planar microdiffusers have a fixed slenderness ratio of 15 and the divergence angle is varied from 4。-120。. The range of the Reynolds number in the experiment is 100-2000. The flow rate is controlled by a precision syringe pump, which pushes the fluid through a section of pipeline, a reservoir, the microdiffuser, and then entering a tank. The pressure in the reservoir is measured by a precision pressure sensor and is used for calculating the loss coefficient of the diffuser. Experimental results show that the loss coefficient increases with decreasing Reynolds number. Microdiffusers with small divergence angles may have larger loss coefficients than those at large angles due to the wall frictional loss. The pressure losses of microdiffusers at large angles are primarily due to flow separation and the effects of viscous loss are very limited.

[1] L. Smith, Micromachined nozzles fabricated with a replicative method 2nd Workshop on Micromachining, Micromechanics and Microsystems “Micromechanics Europe ‘90’”, Berlin, Germany(1990).
[2] E. Stemme, G. Stemme, A valve-less diffuser/nozzle based fluid pump, Sensors and Actuators A: Physical 39, pp.159-167(1993).
[3] A. Olsson, G. Stemme, E. Stemme, A valve-less planar fluid pump with two pump chambers, Sensors and Actuators, A46-47, pp.549-556, 1995.
[4] A. Olsson, P. Enoksson, G. Stemme, E. Stemme, A valve-less planar pump isotropically etched in silicon, Journal of Micromechanics and Microengineering 6, pp.87-91, 1996.
[5] A. Olsson, P. Enoksson, G. Stemme, E. Stemme, Micromachined flat -walled valve-less diffuser pumps, Journal of Microelectromechanical systems 6, pp. 161-166, 1997.
[6] F.M. White, Fluid Mechanics, McGraw-Hill, New York, 1994.
[7] P.W. Rundstadler, F.X. Dolan, R.C. Dean, Diffuser Data Book,Creare, Hanover, NH, 1975.
[8] J.E. Idelchik, Handbook of Hydraulic Resistance, 2nd edn., Haper & Row, New York, 1986.
[9] G. K. Artyushkina, On the hydraulic resistance during laminar fluid in conical duffusers, Tr. LPI, no. 333, pp.104-106, 1973.
[10] T. Gerlach and H. Wurmus, Working principle and performance of the dynamic micropump, Sensors and Actuators A: Physical 50, pp.135-140, 1955.
[11] A. Olsson, G. Stemme, E. Stemme, Diffuser-element design investigation for valve-less pumps, Sens. Actuators A: Phys. 57, pp.137-143, 1996.
[12] X.N. Jiang, Z.Y. Zhou, X.Y. Huang, Y. Li, Y. Yang, C.Y. Liu, Micronozzle/diffuser flow and its application in micro valveless pumps, Sens. Actuators A: Phys 70, pp.81-97, 1998.
[13] A. Olsson, G. Stemme, E. Stemme, Numerical and experimental studies of flat-walled diffuser elements for valve-less micropumps, Sens. Actuators A: Phys. 84, pp.165-175, 2000.
[14] T. Gerlach, Microdiffusers as dynamic passive valves for micropump applications, Sens. Actuators A: Phys. 69, pp.181-191, 1998.
[15] V. Singhal, S. V. Garimella, J. Y. Murthy, Low Reynolds number flow through nozzle-diffuser elements in valve-less micropump, Sensors and Actuators A: Physical 113, pp.226-235, 2004.
[16] K.S. Yang, I.Y. Chen, B.Y. Shew, C.C Wang, Investigation of the flow characteristics within a micronozzle/diffuser, Journal of Micromechanics and Microengineering 14, pp.26-31, 2004.
[17] 共軛焦3D光學表面形貌量測儀使用者訓練教材,國立成功大學工學院系統暨船舶機電工程系與微機電研究所,2004年9月.