Scramjet (Supersonic Combustion Ramjet，超音速燃燒衝壓引擎)是近年來新興研究的科技 之一，NASA 美國太空總署在1995-1996 年即開始著手相關的發展計畫(Hyper-X)，在2004 年 11 月，NASA 的X-43A 已能達到9.6 馬赫的速度刷新了飛行速度紀錄。 Scramjet 目前暫時只 能在高速下運轉，所以當藉由載具達到5 馬赫以上的速度後，再啟動快速噴射裝置使超音速 燃燒衝壓引擎運轉，當大氣中的氧氣被吸入與噴射機內的氫氣結合再加以點燃，便可產生推 進力，由於本身只需攜帶少量的氫當作燃料，氫具高內能、反應快速、燃燒較完全，不會有 什麼廢氣。Scramjet 重量輕，且幾乎不會造成汙染，如此極高速的引擎，對於將來的航空科 技是相當具突破性的研究課題。 本實驗室曾於 1995 年使用Navier-Stokes 方程式搭配雙層代數式紊流模式來模擬超音速衝 壓引擎燃燒室內震波增強混合與燃燒分析[33]並於46th International Astronautical Congress 中發表，有了以往的模擬經驗以及對超音速衝壓引擎的瞭解，本計劃擬使用直接模 擬蒙地卡羅法(DSMC)模擬三維超音速燃燒衝壓引擎(scramjet)之內、外流場，來分析超音速燃 燒衝壓引擎進氣道與燃燒室之混合與燃燒現象。 於計畫第一年(96 年度)，我們模擬三維超音速燃燒衝壓引擎之內流場，於馬赫數5、10 和 15 下之進氣道流場狀態。而計劃第二年(97 年度)，我們以第一年所得到之進氣道模擬結果作 為內流場進氣口之初始狀態來模擬超音速燃燒衝壓引擎之內流場，並搭配不同進氣口凸塊高 度來分析內流場中之混合現象。最後於計畫第三年(98 年度)加入氫氣之化學反應模式來探討 其燃燒現象，並同時邀請屏東科技大學戴昌賢及江庭隆兩位教授加入計算使用Navier-Stokes 方程式搭配雙層代數式紊流模式來模擬超音速燃燒衝壓引擎之內流場，最後再做兩者之比較。 關鍵詞：直接模擬蒙地卡羅法(DSMC)、超音速燃燒衝壓引擎(Scramjet)、Navier-Stokes Scramjet (Supersonic Combustion Ramjet) is an air-breathing engine which is important for the future hypersonic vehicle and the space planes. The concept of an airframe integrated Scramjet has evolved from NASA Langley Research Center program (Hyper-X) for hypersonic air-breathing engine in 1995-1996. In November of 2004, NASA』s X-43A research vehicle achieves the record-breaking flights, Mach 9.6. The oxygen needed by the engine to combust is taken from the atmosphere passing through the vehicle, instead of from a tank onboard. The craft becomes smaller, lighter and faster. This proposal applies the Direct Simulation Monte Carlo method (DSMC) to calculate the inner and outer flow fields of the supersonic combustion ramjet (Scramjet) and analysis the mixing and combustion phenomenon of the inlet and combustor of the Scramjet engine. First, this proposal calculates the outer flow field of the Scramjet engine at Mach 5, 10 and 15. From the former calculated results, the initial flow conditions of the Scramjet combustor inlet can be defined. In order to analysis the mixing phenomenon, the inner flow field of the Scramjet engine is calculating with various inlet step height. Then, the inner flow field of the Scramjet engine is calculating with chemical reaction to analysis the combustion phenomenon inside the engine. Final, this proposal employs the Navier-Stokes equations with the turbulent model (Two-layer algebraic eddy viscosity model) to calculate the inner flow field of the Scramjet engine. The results are compared to the former results from the DSMC simulation.
