內燃機內流場現象之研究

A Study on the Phenomena of the Flow Field in an Internal Combustion Engine

蘇鼎傑(Ding-jie Su)

指導教授 ： 鄧治東

中原大學/工學院/機械工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200374

摘要

內燃機目前係汽、機車主要的動力來源。而內燃機為一熱機，將燃料之化學能轉換成輸出軸之機械能。而汽缸內的流場現象對於引擎的性能有相當重要的影響，因此若能進一步瞭解與分析引擎汽缸內的流場現象，將有助於內燃機的設計。本研究使用由美國Los Alamos國家實驗室針對模擬分析內燃機熱流現象所發展的KIVA-3V計算流體力學程式模擬分析一真實引擎，KIVA-3V可用來計算暫態、二維、三維及含有噴油和亂流的化學反應流場。

一般而言，研究內燃機流場現象的方法主要分為實驗與數值模擬兩種，在實驗方面雖可量測到引擎的實際表現，但難以對整體及細部流場進行了解與探討，所以本研究使用KIVA-3V來模擬進而得到缸內整體流場。除此之外，由於電腦運算能力的快速發展，使得研究者通常會選用數值模擬方法。KIVA-3V是一計算流體力學程式，使用有限體積法中的ALE法則進行數值運算，在油滴行為描述方面使用蒙地卡羅(Monte Carlo)隨機法則，此法則可計算油滴的震盪、扭曲、分裂、碰撞和合併。

本文以RNG (Renormalization Group) 亂流模式探討內燃機內之流場現象，且探討引擎性能參數：滾流比、渦漩比、亂流強度、亂流動能。在容積效率、進氣與壓縮兩衝程之缸內壓力方面，其數值模擬值與實驗值兩者間所顯示之差異在5%以內；此外，對三組最大進氣閥升程之模擬，其所得之容積效率值在趨勢上係屬合理。

關鍵字

容積效率 ； 內燃機 ； 流場 ； KIVA -3V程式

並列摘要

Internal combustion engines are the primary power source for cars and motorcycles. It is the production of mechanical power from the chemical energy contained in the fuel. Because the importance of the phenomena of the flow field in internal combustion engines, this study uses the KIVA-3V code to analyze the flow field. The KIVA-3V code, which was developed at the US Los Alamos National Laboratory, is a powerful tool to analyze the transient, two- and three-dimensional, chemically reactive fluid flows with sprays and turbulence.

In general, the study of the flow field in internal combustion engines uses two methods: the experimental technique and the numerical simulation. Because the experimental technique cannot measure the overall flow field in the cylinder, this study uses the KIVA-3V code to simulate it. Besides, due to the tremendous computing capability available, people usually use numerical simulation for the study. The KIVA-3V code is a computational fluid dynamic program that uses the finite volume method with Arbitrary Lagrangian-Eulerian (ALE) algorithm. The Monte Carlo-based discrete-particle technique used in the fuel sprays model was implemented to describe the behavior of the droplets. The KIVA-3V code is capable of calculating the effects of droplet oscillation, distortion, breakup, collision and coalescence.

The study uses the RNG (Renormalization Group) turbulence model to study the phenomena of the flow field in an internal combustion engine. The engine performance parameters investigated are tumble ratio, swirl ratio, turbulence intensity, and turbulence kinetic energy. In addition, volumetric efficiency and the in-cylinder pressure behavior during the intake and compression stroke were obtained and compared with the experimental data. Their differences are within 5%, using the experimental values as the reference. Furthermore, the volumetric efficiencies for the three sets of intake valve lifts under study appear to be reasonable.

並列關鍵字

an internal combustion engine ； the volumetric efficiency ； the flow field ； the KIVA-3V code

參考文獻

[19]舒小恩,”進氣道角度對內燃機引擎汽缸內流場影響之研究”,私立中原大學機械研究所碩士論文,2000。

[20]廖俊霖,”內燃機引擎進氣閥道內流場之研究”,私立中原大學機械研究所碩士論文,2001。

[2]J-F. Le Coz, S. Henriot, and P. Pinchon, “An Experimental and Computational Analysis of the Flow Field in a Four-Valve Spark Ignition Engine—Focus on Cycle-Resolved Turbulence,” SAE Paper No. 900056.

[3]P. Beladini, C. Bertoli, F. E. Corcione, and G. Valentino, “In-Cylinder Flow Measurements by LDA and Numerical Simulation by KIVA-II Code,” SAE Paper No. 920155.

[4]Z. Han, R. D. Reitz, “Turbulence Modeling of Internal Combusion Engines Using RNG k- Models,” Combust. Sci. and Tech., 1995, Vol. 106, pp.267-295.