輕航機引擎室熱流場的改善研究

The Study on the Improvement of Thermofluid Field of the Engine Compartment of a Light Aircraft

黃勝梁(Sheng Liang Huang)

指導教授 ： 劉思正 ； 蘇智群

國立屏東科技大學/工學院/機械工程系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00034

摘要

輕航機引擎室氣流場分佈的好壞，直接影響到引擎的散熱效率。因此，本文使用計算流體力學(Computational Fluid Dynamics)軟體－Fluent，針對輕航機引擎室的熱流場進行數值模擬與分析，從原始模型的計算結果，發現氣流不易流到引擎汽缸上，造成引擎汽缸的表面溫度過高。本文於是根據原始模型的缺點，在引擎室內設計了導管、導流板以及在整流罩側面增加排氣口位置等6個模型來進行熱流場的改善，最後並依據模擬結果將其中4個較好的改善模型整合成一個模型來增強熱流場的改善效果。從研究的結果可知，在引擎室內增加導流板與導管有助於引導氣流流向引擎汽缸，使引擎汽缸的表面溫度迅速下降，而增設出口位置可以使引擎室內的壓力下降，導致氣流容易通過引擎室，讓流過引擎的氣流速度變大。另外，整合模型的模擬結果顯示，引擎汽缸的表面溫度從原型的555.58K (282.43 C，右前方汽缸)與567.07K (293.92 C，左前方汽缸)降至359.48K (86.33 C，右前方汽缸)與358.75K (85.60 C，左前方汽缸)，符合引擎在運轉時，說明書的溫度規範值，顯示整合模型可以有效改善輕航機引擎的散熱。

關鍵字

輕航機 ； 引擎室 ； 計算流體力學 ； 熱流場

並列摘要

The distribution of thermolfluid fluid of the engine compartment of a light aircraft will directly affect the thermal discharge of an engine. Therefore, this study uses the software of Computational Fluid Dynamics-Fluent to simulate and analyze the thermofluid field of the engine compartment of a light aircraft.The results from the prototype indicate that the airflow dose not flow to the engine cylinder easily, and this causes the surface temperature of engine cylinder too high. Hence this study is based on the defects of the prototype to design the guide pipe, the guide vane in the engine compartment and increase the outlet on the side of the cowling, which are used to establish six improved models. Finally, four improved models, which have better improved thermifluid conditions, are integrated into the model 7. It can be seen from the results of this study, the guide pipe and the guide vane are helpful to guide the airflow to the engine cylinder, and reduce the surface temperature of engine cylinder quickly; the increase of the outlet can decrease the pressure in the engine compartment, make airflow pass through the engine compartment easily, and result in increasing the velocity of airflow. Besides, the result of model 7 indicates that the surface temperature of engine cylinder is reduced from the prototype of 555.58K (282.43 C, the front right of the engine cylinder) and 567.07K (293.92 C, the front left of the engine cylinder) to the integrated model 7 of 359.48K (86.33 C, the front right of the engine cylinder) and 358.75K (85.60 C, the front left of the engine cylinder), it conforms to the temperature specification written on the installation manual for ROTAX 912S aircraft engine.This study reveals that the integrated model 7 improves the thermal discharge of the engine of a light aircraft.

並列關鍵字

Light Aircraft ； Engine Compartment ； Computational Fluid Dynamics ； Thermofluid Field

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