本論文主旨在研究燃燒領域上尚未完全探索之固態燃料於渦漩流場高速衝擊下之燃燒學理。自行設計製作熱流風洞及耐高溫突張燃燒室作為實驗平台，發展量測技術，將高速高溫氣流 (800K~1200K) 吹過背向階梯下游之壓克力燃料板 (固態燃料之通用測試材料)，模擬分析固態燃料衝壓引擎燃燒室中的非穩態引燃過程。研究重點在建立一可靠的固態燃料衝壓引擎模擬平台，並試圖了解此類燃燒室中固態燃料引燃後火焰行為的控制機構與物理意涵。
本研究已完成熱流風洞系統，也對其性能進行基本分析。引燃實驗中觀察到在特定高溫氣流邊界條件下，有數種不同的引燃模式及火焰傳播行為。流場中稍短之滯留時間及溫度的相互競爭，應是造成此多種引燃過程之主要因素；隨著燃料逐漸熱解，迴流區內流體滯留之優勢，亦逐漸被下游預混火焰造成之高溫所取代。另一方面，在引燃過程的高速攝影觀測結果中，觀察到特殊的焰核滾轉現象；固態燃料蒸氣若於流場中再接觸區下游引燃，會產生順向及逆向的火焰傳播，其中逆向火焰傳播由於承受較大的對流熱損失，故時序上較順向傳播為晚。此為前人文獻中較少記載之現象，值得未來深入進行討論。
本研究於學術上之具體成果為: 提供固態燃料在週期性渦漩衝擊下之燃燒新現象，成功發展高速高溫之熱流風洞設計製造及操控技術，奠定非穩態燃燒診測技術之基礎。對未來能源領域方面固態燃料之應用特性，及高速推進系統之研究與發展有所助益。

This research work is to study the ignition process of a PMMA slab installed in a sudden-expansion chamber, simulating that occurring in a solid fuel ramjet (SFRJ) combustor. The subject was rarely published in the combustion community before and has long been considered essential to practical application of solid fuel. For the study a hot flow wind tunnel with a sudden-expansion test section has been fabricated. The slab is set immediately downstream of a backward-facing step, and a high-temperature oxidizing stream is provided to flow over the slab.
To date the wind tunnel is fully operational and its performance has been extensively evaluated. For a given step height and prescribed velocity, temperature and oxygen concentration of the oxidizing stream, distinct ignition and flame spread phenomena have been observed. Data show that the ignition features are determined by the competition between two dominant variables, the residence time and temperature. As pyrolysis of the solid fuel proceeds, dominance of residence time is gradually replaced by high temperature, which is induced by the premixed flame formed downstream. Thus, instead of occurring within the recirculation zone, ignition is found more likely to take place near the rear end of the fuel slab.
Images acquired via high-speed photography reveal interesting, however, unrecognized “rolling” behavior of flame kernels that remains to be further identified. Both concurrent and opposed flame spread are observed if ignition occurs downstream of the reattachment zone. The opposed flame spread is noticed to occur later than the concurrent mode since it suffers more severe convective heat loss.
Besides the establishment of a reliable SFRJ simulation platform and corresponding diagnostic techniques, this research provides more physical insights into combustion features of solid fuel in a sudden-expansion combustor, which is commonly seen in industrial applications. Further investigation into this subject is believed to be critical for future development of power and high-speed aero-propulsion systems.

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