本文利用熱傳學與流體力學理論，以數值方法模擬氣冷及水冷式機車引擎熱液動之性能分析。針對氣冷式機車引擎以有限元素法與擬穩態模型配合平均熱傳係數（h）與其相對平均溫度（T）之邊界條件來分析進、排氣閥、活塞、汽缸頭與汽缸體之溫度場，並探討活塞於上死點(TDC)及下死點(BDC)時各元件的溫度分佈與熱傳率之差異性對引擎的影響。而水冷式機車引擎則對導風罩、輪胎與擋泥蓋至冷卻水箱之車體空間，建立幾何模型並作數值模擬，以探討整體流場之分佈趨勢，進而分析各種行車速度下流入水箱速度之分佈趨勢。輔以水箱熱液動性能電腦輔助設計軟體來預估水箱的熱傳量，並與實車模型實驗量測之熱傳量相互比較。
　　由數值結果可知燃燒室內各元件之熱傳率所佔比例：進氣閥為11％、排氣閥為8％、汽缸頭為21％、活塞為35％與汽缸為25％。而模擬行車速度為2 m/s~20 m/s時，可知流入水箱的平均速度約為行車速度的20％~22％。當導風罩α=-10°相對於α=0°時之流入水箱平均速度增加10.2％，α=+10°時則減少3.7％。而α=-10°之預估熱傳量增加8.4％，α=+10°時則減少3.1％。並由CFD模擬所得之流入水箱速度，輔以水箱熱液動性能電腦輔助設計軟體來預估水箱的熱傳量，與實車模型實驗量測之熱傳量相互比較，誤差為11%~17%之間。

This study utilizes heat transfer and computational fluid dynamics theory to numerically analyze the 3-D thermal-hydraulic characteristic for motorcycle engines with air-cooling and water-cooling, respectively.
For air-cooling motorcycle engine, the finite element method has been used to solve the temperature field and heat transfer rate for each component (intake valves, exhaust valves, piston, piston rings, cylinder head and cylinder) of motorcycle engine when the piston is in the Top Dead Center (TDC) and Bottom Dead Center (BDC), respectively. For water-cooling motorcycle engine, the flow field and the velocity distribution for air flow over the space between the grille, tire, the mud cover and radiator of the motorcycle were analyzed for different motorcycle speed and grill angles. In addition, the heat transfer performances of the radiator were examined in conduction with the radiator computer-aided design radiator software.
The results showed that the fraction of heat transfer rate for each component are as follows: intake valves 11％, exhaust valves 8％, cylinder head 21％, the piston 35％ and the cylinder 25％. The average velocity inside the radiator is only about 20% to 22% of inlet velocity when the inlet velocity is varied from 2 m/s to 20 m/s. When the grille angle is decreased α=-10°,the radiator average velocity and the heat transfer rate are increased 10.2% and 8.4 %, respectively, while the grille angle is increased α=+10°,the radiator average velocity and the heat transfer rate are decreased 3.7% and 3.1%, respectively. The numerical prediction is in good agreement with experimental data within 17%.

1.Annand, W.J.D., “Heat Transfer in the Cylinders of a Reciprocating Internal Combustion Engine”, Proc. Instn. Mech. Engrs 177, p. 973, 1963.
2.Woschni, G., “A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine”, SAE Paper 670931, 1967.
3.Alkidas, A. C., “Heat transfer characteristics of a spark-ignition engine”, ASME J.Heat Transfer, 102 189-193, 1980.
4.Alkidas, A. C. and Myers, J. P. , ”Transient heat-flux measurements in the combustion chamber of a spark-ignition engine”, ASME J.Heat Transfer104 62-67, 1982.
5.Yoshiteru, E., Shoichi F. and Koh M., “Heat Loss to Combustion Chamber Wall of 4-stroke Gasoline Engine”, Bulletin of JSME, Vol. 28, No. 238, April 1985.
6.Worthen, R. P. and Rauen, D. G. , “Measurement of Valve Temperaturesand Strain in a Firing Engine”, SAE Paper 860356, 1986.
7.Heywood, J. B., ” Internal combustion engine fundamentals”, McGraw-Hill, New York, Chapter 12,1988.
8.Wu, H. W. and Chiu, C. P., “ Computer diagnosis system for thermal analysis of engine piston”, Warme-und Stoffubertragung 24,203-210,1989.
9.Wu, H. W. and Chiu, C. P., “Study of Finned-Wall Cylinder Temperature in a Two Stroke Gasoline Engine-Comparison of Analytical and Experimental Results”, SAE Paper 871655, 1989.
10.Prasad, R. and Samria, N. K., “Transient Heat Transfer Studies on a Diesel Engine Valve”, Int. J. Mech. Sci., vol. 33, no. 3, pp. 179–195, 1991.
11.Cherrie, J. M., “Factors Influencing Valve Temperatures in Passenger Car Engines”, SAE Paper 650484, 1965.
12.Worthen, R. P. and Tunnecliffe, T. N., “Temperature Controlled Engine Valves”, SAE Paper 820501, 1982.
13.Johan, Z., Moraes, A. C. M., Buell, J. C. and Ferencz, R. M., “In-Cylinder Cold Flow SimulationUsing a Finite Element Method”, Comput. Meth. Appl. Mech. Eng., vol. 190, pp. 3069–3080, 2001.
14.Harigaya, Y., Toda, F. and Suzuki, M., ” Local Heat Transfer on Combustion Chamber Wall of a Spark Ignition Engine”, pp. 1567–1575, SAE paper, No. 931130, 1993.
15.Hayes, T. K., White, R. A. and Peters, J. E., “Combustion chamber temperature and nstantaneous local heat flux measurements in a spark ignition engine”, pp. 1–9, SAE paper, No. 930217, 1993.
16.Heisler, H., “Advanced Engine Technology, Society of Automotive Engineers“, Hodder Headline Group, London, 1995.
17.Yang, L. C., Hamada, A. and Ohtsubo, K., “Engine Valve Temperature Simulation System “, SAE Paper 2000-0100564, 2000.
18.Liu, Y. and Reitz, R. D., “Modeling of heat conduction within chamber walls for multidimensional internal combustion engine simulations”, Int. J. Heat Transfer. Vol.41, Nos 6-7,pp.859-869, 1998.
19.Grau, J. H., Garcia, J. M., Garcia, J. P., Robles, A.V. and Pastor,R.R., “ Modeling Methodology of a Spark-Ignition Engine and Experimental Validation Part I: Single-Zone Combustion Model ”, SAE Paper, No. 2002-01-2193, 2002.
20.Lee, C. W., Kim, C. W. and Kim, S.P., “A steady of heat flux in a constant-volume combustion chamber ”, Automobile Engineering , Proc. Instn Mech .Engers Vol.217 Part D, 2003.
21.Shojaefard, M. H., Noorpoor, A. R. Bozchaloe, D. A. and Ghaffarpour, M., “TRANSIENT THERMAL ANALYSIS OF ENGINE EXHAUST VAVEL ”, Numerical Heat Transfer, Part A, 48: 627- 644, 2005.
22.Wu, Y.Y., Chen, B.C. and Hsieh, F.C., “ Heat transfer model for small-scale air-cooled spark-ignition four-stroke engine ”, International Journal of Heat and Mass Transfer 49 3895-3905, 2006.
23.Kim, H. M., Choi, K. S., Kim, C. H. and Lee, D.J., ”Development of Surface Welding Method for Surface Temperature Measurement of an IC Engine’s Combustion Chamber”, Key Engineering Material Vols. 306-308 pp 453-458, 2006.
24.Mohammadi, A., Yaghoubi, M. and Rashidi, M., “Analysis of local convective heat transfer in a spark ignition engine”, International Communications in Heat and Mass Transfer 35 215-224, 2008.
25.Huh, K.Y., Chang, I. P. and Martin, J. K., “A Comparison of Boundary Layer Treatments for Heat Transfer in IC Engines”, SAE Paper 900252, 1990.
26.Atkinson, K. N., Drakulic, R., Heikal, M. R. and Cowell, T. A., “Two-and-three-dimensional numerical models of flow and heat transfer over louver fin arrays in compact heat exchangers”, International Journal of Heat and Mass Transfer 41 pp.4063-4080, 1998.
27.Wang, C. C., Chang, Y, P. and Chi, K. Y., “A study of non-redirection louver fin-and tube heat exchanger ”, Proc. Instn. Mech Engrs Vol.212 part C, pp.1-13, 1998.
28.Wang, C. C., Chi, K. Y. and Chang, Y. J., “An experimental study of heat transfer and friction characteristics of typical louver fin-and tube heat exchangers”, International Journal of Heat Mass Transfer Vol.41, pp.817-822, 1998.
29.Lawrence, N. and Kortekaas, H. Y. P., ”DECSIM-A PC-Based Diesel Engine Cycle and Cooling System Simulation Program”, Mathematical and Computer Modelling 33 565-575, 2001.
30.Yang, Z., Boseman, J., Shen, F. Z. and Acre, J. A., ”CFRM concept for vehicle thermal system”, SAE Paper No. 2002-01-1207, 2002.
31.Witry, A., Al-Hajeri, M. H. and Bondok, A. A., “Thermal performance of automotive aluminium plate radiator” ,Applied Thermal Engineering, 25, 1207-1218, 2005.
32.Oi, Z. G., Chen, J. P. and Chen, Z. J., “Analysis and simulation of mobile air conditioning system coupled with engine cooling system”, Energy Conversion and Management 48 1176-1184, 2007.
33.Hsieh, C.T. and Jang, J. Y., ” 3-D Thermal-Hydraulic Analysis for Airflow Over a Radiator and Engine Room ”, International Journal of Automotive Technology, Vol.8, No.5, pages 659-666, 2007..
34.Abaqus Theory Manual, Version 6.7, ABAQUS, Inc. Dassault Systèmes, 2007.
35.CFD-ACE(U),CFD Research Corporation,Alabama,USA, 2003.
36.Launder, B. E. and Spalding, A. D.,“Mathematical Models of Turbulence” , pp. 90-100, Academic, London, 1972.
37.Chang, W. J. and Jang, J. Y. “Non-Darcian Effects on Vortex Instability of a Horizontal Natural Convection Flow in a Porous Medium”, International Journal of Heat and Mass Transfer, Vol. 32, No. 3, PP. 529-539, 1989.
38.Wang, C. L. and Jang, J. Y. ” The Developing Mixed Convection in a Vertical Non-Darcian Porous Channel”, The Chinese Journal of Mechanics, Vol. 10, No.2, PP. 131-144, 1994.
39.GT-POWER USER MANUAL.
40.張錦裕與蔡瑛吉, “水箱熱液動性能電腦輔助設計軟體”光陽公司研究報告, 2009.