乙醇與異辛烷預混火燄傳播速度之研究

The Flame Propagation Velocity of Premixed Ethanol/Air and Iso-Octane/Air Mixtures

王興華(Ching-Hua Wang) ； 王琮熙(Tsung-Si Wang)

《中國航空太空學會學刊》 27卷2期 (1995/06) Pp. 93-101

https://doi.org/10.6124/TAASRC.199506_27(2).02

摘要

本文係利用一組可調間距式對噴噴嘴，以產生一組穩定的、靜止的、層流的、預混的、雙層且對稱的絕熱平面火燄，並配合雷射杜普勒測速儀(LDA)的使用，以量取此預混火燄的絕熱火燄傳播速度。
首先以LDA量測沿火燄商中心流線之速度分佈及其梯度，以取得在此流體延展率下的絕熱火燄傳播速度。實驗中於固定預混燃氣進氣狀況下，藉著調整對嘖嘖嘴間距，得到了一些預混、預揮發的液體燃料在不同延展率下的火燄傳播速度，藉以瞭解火燄傳播速度與延展率在不同情形下的關係；進而以外插方式求得無延展狀況時之絕熱火燄傳播速度。實驗的最後結果則包含了在不同預混燃氣進氣狀況下：例如不同進氣當量比與進氣溫度，無延展作用的絕熱火燄傳播速度。
實驗中使用直徑0.1~1µm的氧化鎮粉末作爲LDA量測的干涉粒子，所使用的液態燃料則爲乙醇與異辛烷，至於最低火燄延展率則可控制在~100sec^(-1)自，而未燃混合氣的進氣溫度則在80至140℃。
首先以LDA量測沿火燄商中心流線之速度分佈及其梯度，以取得在此流體延展率下的絕熱火燄傳播速度。實驗中於固定預混燃氣進氣狀況下，藉著調整對嘖嘖嘴間距，得到了一些預混、預揮發的液體燃料在不同延展率下的火燄傳播速度，藉以瞭解火燄傳播速度與延展率在不同情形下的關係;進而以外插方式求得無延展狀況時之絕熱火燄傳播速度。實驗的最後結果則包含了在不同預混燃氣進氣狀況下：仿如不同進氣當量比與進氣溫度，無延展作用的絕熱火燄傳播速度。
實驗中使用直徑。1~1µm的氧化鎮粉末作為LDA量測的干涉粒子，所使用的液態燃料則為乙醇與異辛烷，至於最低火燄延展率則可控制在~100sec^(-1)自，而未燃混合氣的進氣溫度則在80至140℃。

關鍵字

絕熱火燄傳播速度 ； 火燄延展率

並列摘要

This report presents an experimental methodology which can be used to determine the adiabatic flame propagation velocity accurately the basic idea is using a set of opposed flow burners, to generate two steady, stationary, laminar, premixed and symmetrical flames and cooperating with the Laser-Doppler-Anemometry (LDA) measurement.
The LDA was used to measure the fluid velocity profile along the centerline of the burner flow, by which the adiabatic flame propagation velocity as well as the flame stretch rate could be obtained. By simply varying the distance between the two opposed burners with fixed inlet conditions, we then measured the adiabatic flame propagation velocites under different flame stretch rates. By further extrapolating these results to the zero-strech condition, we thus obtained the stretchless adiabatic flame propagation velocity. The final experimental results included the stretchless adiabatic flame propagation velocity under different fuel/air equivalence ratios and precheated temperatures of the inlet combustible mixtures.
In the study, fine powders of MgO with size about 0.1~1.0 µm were used to serve as the LDA seeding particles; pre-vaporized Iiquid ethanol and iso-octane were used as the tested fuels; the minimum f1ame stretch rate obtained was about 100sec^(-1), and the inlet temperature of the premixed combustible mixture was about 80 to 140℃.
The LDA was used tomeasure the fluid velocityprofile alongthe centerline of the burner flow, by which the adiabatic flame propagation velocity as well as the flame stretch rate could be obtained. By simply varying the distance between the two opposed burners with fixed iulet conditions, we then measured the adiabatic flame propagation velocites under different flame stretch rates. By further extrapolating these results to the zero-strech condition, we thus obtained the stretchless adiabatic flame propagation velocity. The final experimental results included the stretchless adiabatic flame propagation velocity under different fuel/air equivalence ratios and precheated temperatures of the inlet combustible mixtures.
In the study, fine powders of MgO with size about 0.1~1.0 µm were used to serve as the LDA seeding particles; pre-vaporized Iiquid ethanol and iso-octane were used as the tested fuels; the minimum f1ame stretch rate obtained was about 100sec^(-1), and the inlet temperature of the premixed combustible mixture was about 80 to 140℃.

並列關鍵字

adiabatic flame propagation velocity ； flame stretch rate