臺灣博碩士論文加值系統

本文之研究乃是針對突縮(Suddenly Contraction)幾何外型之注油器管(Injector Orifice)內流場，在不同的L/D與雷諾數下進行層流、紊流數值的模凝，同時以經假設簡化後的兩相之液相流與氣相流場(比率為10000:1)狀態，利用所得的流場中壓力分布情形，與給定操作環境之工作流能的蒸汽壓相比較，找出流場中局部壓力小於流體之蒸汽壓與雷諾數變化之關聯，並加入空蝕係數作考量，再以STAR-CD計算軟體予以比對，來驗證軟體的正確性與可靠度。藉以簡單地預測空蝕(Cavitation)現象發生的條件，同時也估計可能發生空蝕現象發生位置的分佈。
在對注油器管兩相流內流場的暫態計算之後，發現當雷諾數增加
到某一值時，流場會於收縮段入口處會產生迴流區，形成那脈縮(Vena
Contracta)現象，而此迴流區則隨著雷諾數之加大而增長。在空蝕
現象預測方面，本研究發現當流場中局部壓力在雷諾數增加時會降低
到等於或小於流體之蒸汽壓，與觸發空蝕現象連帶關係，進而希望能
提供判斷突縮幾何形狀之注油器管內流場發生空蝕現象的時機。

This study briefly focuses on the study of cavitated flow phenomenon in an injector orifice. Numerical computation of laminar and turbulence flow simulation with aspect ratio of 10 is performed. It is assumed that the ratio of liquid and vapor flowfield (ratio 10000:1). In this study, the STAR-CD is used to perform the calculation to compare with the related experimental data. It is shown that the increase of Reynolds Number to some degree will cause flow separation around corners and causes cavitation. It is also discovered that the cavitation phenomenon appears as the pressure is reduced to the local saturation pressure.

目 錄
誌 謝 …………………………………………………. I
中文摘要 …………………………………………………. III
英文摘要 …………………………………………………. IV
目 錄 …………………………………………………. V
圖 目 錄 ………………………………………………….
表 目 錄 …………………………………………………. VII
IX
符號說明 …………………………………………………. X
第一章 緒 論 …………….………………………….. 1
1-1 引 言 ……………………………………….. 1
1-2 文獻回顧 ……………………………………… 3
1-3 研究目的與方法 ……………………………… 10
第二章 物理問題 ………………………………………. 12
2-1 空蝕物理現象簡介 …………………………… 12
2-2 空蝕係數物理意義 …………………………… 13
2-3 空蝕現象物理問題假設 ……………………… 15
第三章 數值模式 ……………………………………… 18
3-1 基本流場守恆方程式 ………………………… 18
3-2 標準方程式 ………………………………… 18
3-3 空蝕數值模式 ……………………………… 20
第四章 結果與討論 ……………………………………… 23
4-1 突縮管流場之格點獨立驗證 ………………… 23
4-2 突縮管之流場與空蝕分析……………………… 26
4-3 突縮管之壓力差測試流場分析……………… 28
4-4 突縮管之兩相流與單相(紊流)流場空蝕分析… 33
第五章 結論 …………………………………………… 41
參考文獻 ………………………………………………… 43

1.Marcus F. Heidmann, Richard J.Priem, and C. Huimphery “A Study of Spray Formed by Two Impinging Jets”, NACATN 3835, March 1957.
2.W.H.Nurick “Orifice Cavitation and Its Effect on Spray Mixing”, Journal of Fluid Engineering, December 1976, pp.681-687
3.F. Durst and T. Loy, “Investigations of Laminar Flow in A Pipe with Sudden Contraction of Cross Sectional Area”, Computers & Fluids Vol. 13, No. 1, pp.15-36, 1985.
4.H. Hiroyasu , M Arai , and M. Shimizu “Break-up Length of a Liquid Jet and Internal Flow in a Nozzle“ , ICLASS-91 Gaithersburg , MD, U.S.A. July 1991, pp.275-282
5.M. C. Kine, R.D. Woodward , R.L. Burch , F.B. Cheung, and K. K. Kuo “Imaging of Impinging Jet Breakup and Atomization Processes Using Copper-Vapor-Laser-Sheet-Illuminated Photography”, Chemical Propuision , Non-intrusive Combustion Diagnostics , May 1993, The Netherlands.
6.T. R. Ohrn, D. W. Senser, and A. H. Lefebvre, “Geometrical Effect on Discharge Coefficients for Plain-Orifice Atomizers”, Atomization and Sprays, vol., no. 2, pp.137-153, 1991.
7.Ja Ye Koo and Jay K. Martin, “Near-Nozzle Characteristics of A Transient Fuel Spray”, Atomization and Sprays, vol. 5, pp.107-121, 1995.
8.Lu He and Francisio Ruiz, “Effect of Cavitation on Flow and Turbulence in Plain Orifice for High-Speed Atomization”, Atomization and Sprays, vol. 5, pp.569-584, 1995.
9.David P. Schmidt, Christopher J.Rustand, and M. L. Corradini “A Fully Compressible, Two-Dimensional Model of Small, High-Speed, Cavitating Nozzles”, Atomization and Sprays, vol. 9, pp.255-276, 1999.
10.David P. Schmidt, Tzay-Fu Su, Kayhan H. Goney, P. V. Farrel, M. L. Corradini, “Detection of Cavitation in Fuel Injector Nozzles” , Engine Research Center, University of Wisconsin, Madison. WI 53706, 1996.
11.M. C. Kine, R.D. Woodward , R.L. Burch , F.B. Cheung, and K. K. Kuo “Imaging of Impinging Jet Breakup and Atomization Processes Using Copper-Vapor-Laser-Sheet-Illuminated Photography”, Chemical Propuision , Non-intrusive Combustion Diagnostics , May 1993, The Netherlands.
12.N. Tamaki, M. Shimizu, K. Nishida and H. Hiroyasu, “Effect of Cavitation and Internal Flow on Atomization of A Liquid Jet”, Atomization and Sprays, vol. 8, pp.179-197, 1998.
13.Y. Delannoy and J. L. Kueny, “Two Phase Flow Approach in Unsteady Cavitation Modeling”, Cavitation and Multiphase Flow Forum, ASME FED, Vol. 98, pp. 153-158, 1990.
14.M. A. Rizk and S. E. Elghobahsi, “A Two-Equation Turbulence Model for Dispersed Dilute Confined Two-Phase Flow”, Int. J. Multiphase Flow, Vol. 15, pp. 119-133 (1989).
15.A. Adeniji-Fashola and C. P. Chen, “Modeling of Confined Turbulent Fluid-Particle Flows Using Eulerian and Largrangian Schemes”, Int. J. Heat Mass Transfer, Vol. 33, pp. 691-701 (1990).
16.R. T. Issa and P. J. Oliverira, “Numerical Prediction of Phase Separation in Two-Phase Flow Through T-Junctions”, Comput. Fluids, Vol. 23, pp. 347~372 (1994).
17.J. Y. Tu and C. A. J. Fletcher, ”Numerical Computation of Turbulent Gas-Solid Particle Flow in 90。Bend”, AlChE J., Vol.41, pp. 2187-2196(1994).
18.David P. Schmidt, Christopher J. Rutland and M. L. Corradini, “A Numerical Study of Cavitating Flow Through Various Nozzle Shapes”, Engine Research Center, University of Wisconsin, Madison. 971597.
19.David P. Schmidt, M. L. Corradini, “Analytical Prediction of the Exit Flow of Cavitating Orifices”, Engine Research Center, 1500 Engineering Dr. University of Wisconsin, Madison. WI 53706.
20.David P. Schmidt, M. L. Corradini, “One-Dimensional Analysis of Cavitating Orifices”, Engine Research Center, 1500 Engineering Dr. University of Wisconsin, Madison. WI 53706.
21.卓英吉, “以數值方法探討注油器管內流場之空蝕現象”, 國立成功大學航空太空工程研究所碩士論文, 1997.
22.楊授印, “以數值方法探討噴流機構內流場空蝕現象” , 國立成功大學航空太空工程研究所碩士論文, 1998.
23.洪健元,”內流場空蝕現象之初步數值模擬”, 中華大學機械與航太工程研究所碩士論文, 1999.
24.R. T. Knapp, J. W. Daily, and F. G. Hammitt, “Cavitation,” McGraw-Hill Book Company, 1970.
25.Computational Fluid Dynamics Softwasre , “STAR-CD Version 3.10 User Guide”, 1999 Computational Dynamics Limited.
26.Computational Fluid Dynamics Softwasre , “STAR-CD Version 3.10 Tutorial Manual vol.1”, 1999 Computational Dynamics Limited.
27.Computational Fluid Dynamics Softwasre , “STAR-CD Version 3.10 Tutorial Manual vol.2”, 1999 Computational Dynamics Limited.
28.Computational Fluid Dynamics Softwasre , “STAR-CD Version 3.10 User Guide”, 1999 Computational Dynamics Limited.