本研究以實驗與數值模擬方法探討成功大學航太科技研究中心（ASTRC）反射式震波風洞中的暫態流場特性與有效測試時間。結果顯示，雙隔膜配置會產生理想一維震波管理論所無法預測的額外次級波系，且這些波會在風洞內反覆傳播與反射，進而在儲氣區與測試段中造成額外的壓力擾動。隔膜未完全開啟會導致額外的流動損失，使入射震波減弱，並降低儲氣區與測試段中的溫度與壓力條件。 數值結果進一步顯示，震波系與接觸區之間的交互作用會促使驅動氣體沿近壁面區域向下游傳輸，導致測試氣體提早受到污染。除了進行包含氦氣-空氣物種傳輸的數值模擬與動態壓力量測外，本研究亦利用圓錐模型的紋影可視化實驗來辨識驅動氣體的到達。當測試段中的氣體由空氣逐漸轉變為氦氣-空氣混合氣體時，模型周圍的流場結構會出現可觀察的變化，顯示此方法具有作為非侵入式偵測測試氣體組成變化方法的潛力。根據噴嘴內流場的建立過程與驅動氣體污染情形，數值模擬預測的有效測試時間約為 2.43 ms，而實驗結果顯示有效測試時間較短，約為 1.0 至 1.74 ms。因此，實驗所得的有效測試時間較數值預測短約 0.69 至 1.43 ms。整體而言，研究結果顯示，ASTRC 反射式震波風洞的有效測試時間受到非理想隔膜效應、震波系動態行為以及驅動氣體傳輸的顯著影響，而結合數值模擬與實驗的方法可作為評估該風洞有效測試時間的一種潛在方法。

This study experimentally and numerically investigates the transient flow characteristics and effective test time of the ASTRC reflected shock tunnel. The results show that the double diaphragm configuration generates additional secondary wave structures that are not predicted by ideal one-dimensional shock-tube theory, and these waves repeatedly propagate and reflect within the facility, producing additional pressure disturbances in the reservoir and test section. Incomplete diaphragm opening causes additional flow losses, weakening the incident shock and reducing temperature and pressure conditions in the reservoir and test section. The numerical results further show that the interaction between the shock train and the contact region promotes the downstream transport of driver gas along the near-wall region, leading to premature contamination of the test gas. In addition to simulations with helium-air species transport and dynamic pressure measurements, schlieren visualization of a cone model was employed to experimentally identify the arrival of driver gas. The changes in the flow structure around the model as the gas in the test section transitions from air to a helium-air mixture demonstrate that this approach provides a potential non-intrusive method for detecting changes in test gas composition. Based on flow establishment in the nozzle and driver gas contamination, the numerical simulation predicts an effective test time of approximately 2.43 ms, whereas the experimental results indicate a shorter effective test time of approximately 1.0 to 1.7 ms. The experimental value is therefore approximately 0.73 to 1.43 ms shorter than the numerical prediction. Overall, the results demonstrate that the effective test time of the ASTRC reflected shock tunnel is strongly influenced by non-ideal diaphragm effects, shock train dynamics, and driver gas transport, and that the combined numerical and experimental approach provides a potential method for evaluating the effective test duration of the facility.

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