含可燃氣共伴流對於環形貧油火焰之穩焰機制

Mechanism of annular lean flame stabilization by air co-flow with combustible gas

王沛盛(Pei-Sern Ong)

指導教授 ： 楊鏡堂

國立臺灣大學/工學院/機械工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02359

摘要

本研究選用三環燃燒器作為載具，藉由其幾何形狀所產生的鈍體效應，也透過各環流場之間的交互作用來達到穩焰效果，從而改善甲烷貧油燃燒不穩定性， 在外環空氣共伴流穩焰效果的基礎上，本研究也探討含少量燃料之外環燃氣共伴流的穩焰效果。在逐步減少外環燃料含量及流速的情況下，以粒子影像測速儀(PIV)和化學螢光法來觀察燃燒流場。
外環純空氣共伴流必須在特定流速(0.33 m/s)以上方能產生穩焰效果，在外環混入燃料後，兩環的交互作用將不僅僅侷限於流場上的因素，也包括了燃燒化學反應層面上的影響。為了釐清外環少量燃料之化學性質對於穩焰效果之影響，本研究將外環流速調控在0.33 m/s以下。此外並以甲烷和丙烷作為外環燃料，以了解不同燃料種類在熱值或流量相同的情況下的穩焰效果。
研究結果顯示，以丙烷預混燃氣作為外環共伴流可獲得比甲烷預混燃氣更好的穩焰效果。丙烷預混燃氣除了能在更低的外環燃料流量下達到穩焰效果之外，也可在更低的外環流速下產生相同效果。而甲烷僅能在外環燃料流量為0.3 L/min時達到穩焰效果。本研究比較外環燃料流量和外環流速對於穩焰效果的影響，發現前者對於穩焰效果有著更顯著的影響。

關鍵字

穩焰效果 ； 粒子影像測速儀 ； 化學螢光法 ； 共伴流

並列摘要

In this present study, unstable annular methane-air premixed flame, of which the equivalence ratio is 0.85, has been tried to stabilize by different combustible outer co-flow. Methane and propane have been used as fuel in the outer annular premixed co-flow. The effects of combustible co-flow with respect to different combinations of injection velocities (Uout = 0.1-0.3 m/s) and fuel proportion on annular lean flame, are experimentally studied in a bluff-body multi-ring burner by flame image, flow path line, high speed Particle Image Velocimetry (frame rate = 1000 fps) and Chemiluminescene.
In the available literatures, dried air co-flow has been shown capable of stabilizing the unstable annular methane-air premixed flame with an injection velocity at least 0.33 m/s. The injection velocity of combustible co-flow was kept lower than 0.33 m/s so that the effect of fuel dilution (in the outer co-flow) on flame stabilization can be observed more conveniently.
Results show that propane-air premixed co-flow is more effective than methane-air on flame stabilization. Propane-air premixed co-flow can stabilize the unstable annular flame under all studied conditions; nevertheless, methane-air premixed co-flow merely achieves the same results at the flow rate of 0.3 L/min. On the contrary, the influences of outer co-flow velocities are less significant on the flame stabilization in all considered cases.

並列關鍵字

PIV ； Chemiluminescence ； stratified combustion ； flame stabilization

參考文獻

林泓瑋，2010，“環形貧油火焰特性與注入空氣共伴流之影響”，國立台灣大學機械工程學系碩士論文

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