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A Design and Analysis of Novel Non-Premixed Dual-Swirling Combustion Nozzle
|Contributors: ||NTOU:Department of Mechanical and Mechatronic Engineering|
|Issue Date: ||2011-06-28T07:38:23Z
|Abstract: ||本研究以太極型之控制圓盤，置於燃燒器上用以控制流場特性，經由此新型設計，可有效提升原燃燒器燃燒效率，最終達到節能減碳的目的。本實驗將太極型控制圓盤置於燃燒器出口處，流體經過其機構時，會將大部分軸向動量轉變成徑向動量，而產生旋流的效果提升其紊流強度。實驗方式為使用雷射光頁輔以煙線流場觀測技術，探討出受太極型控制圓盤所調制出的各流場型態，再於中心噴流釋放CO2氣體，量測其濃度分佈情形，而得知各特徵模態的混合能力。再使用熱電偶、拍照攝影技術等實驗方法，討論出火焰流場其特徵模態、火焰高度、溫度分佈、熱量釋放率。經由上述實驗方式，在等溫流場時，可區分為以下模態：噴流模態(Jet flow)、雙迴流泡模態(Dual bubble)、偏向流模態(Deflect flow)、不穩定流模態(Unstable flow)、紊流模態(Turbulent flow)。不穩定流模態(Unstable flow)其混合能力為最佳，如再配合上12道膛線噴嘴，其混合效率幾乎為100%。於火焰流場時，可區分為以下模態：噴流火焰模態(Jet flame)、閃爍火焰模態(Flickering flame)、迴流火焰模態(Recirculated flame)、橫八字型火焰模態(Lazy-eight flame)、旋流火焰模態(Swirling flame)、跳脫火焰模態(Lifted flame)。以橫八字型火焰模態，其熱量釋放率為最佳。故使用太極型控制圓盤於燃燒器時，相較於噴嘴其整體燃燒總熱量釋放率可大幅提升約50%。|
This study utilized a TaiChi-type disc to modulate the flow fields behind a combustor. The novel TaiChi-type disc increases the combustion efficient significantly, and therefore the goal of energy saving and carbon reduction. The TaiChi-type disc was installed at the exit of a combustor. Most of the axial momentum was transformed to the radial momentum when the flow passed through the TaiChi-type disc. Therefore, the turbulence intensity was increased. A laser-light sheet and the smoke-wire flow visualization scheme were utilized to explore the flow characteristics modulated using the TaiChi-type disc. Furthermore, the mixing efficiency of the characteristic modes was determined by measuring the concentration of carbon dioxide exhaled from the disc center. Additionally, the flame modes, flame length, temperature distribution and the heat-release rate were determined using the thermal couple and direct photography. The experimental results revealed that the isothermal flow fields might be categorized into five modes, that is, the jet flow, dual bubble, deflect flow, unstable flow and turbulent flow modes. The highest mixing efficiency occurs in the unstable flow mode. Especially, the addition of a 12-rifled nozzle increase the mixing efficiency near 100% in the unstable flow mode. Moreover, the flame fields were classified into six flame modes, that is, the jet flame, flickering flame, recirculated flame, lazy-eight flame, swirling flame and the lifted flame modes. The highest heat-release rate occurs in the lazy-eight flame mode. Consequently, the TaiChi-type modulated combustor can increase the global heat-release rate about 50% higher than solitary combustor.
|Appears in Collections:||[機械與機電工程學系] 研究計畫|
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