| 摘要: | 此研究是描述預混火焰聲波振盪之情況以 探討固體火箭燃燒不穩定之問題。探討主題為 火焰之輻射量測及火焰所激發之聲波振盪。研 究結果發現,在某些當量比之下,會產生週期性 的火焰輻射及壓力振盪;且火焰以多頻振盪,其振盪的主頻率與壓力振盪的主頻率可能不同。 火焰輻射之振盪頻率隨當量比之減少而減低, 同時,聲波場之存在並不影響火焰之振盪。火 焰激發之聲波振盪會因振盪頻率不同而產生加 強或減弱之現象。當聲波振盪之頻率與實驗長 管之自然頻率接近時,有加強聲波場之現象;反 之,則聲波振盪會被減弱。
This research is concerned with the study of sound generation by simulated solid rocket premixed flames located on the sidewall of a long rectangular duct. Specifically, the flame radiation, i.e., light emission, of the flame and the induced acoustic oscillation were investigated. These studies reveal that the self-excited oscillatory flame radiation and the induced pressure oscillation were observed only at certain equivalence ratios. In addition, the flame oscillates with several frequencies and the dominating frequency can be different from that of the induced pressure oscillations. The frequencies of the flame oscillation decreased as the equivalence ratio decreased, and were not affected by the presence of acoustic wave. However, the acoustic oscillations could be enhanced or damped by the flame oscillation depending on the frequency of the oscillations. Driving of acoustic wave occurred when the frequencies of the induced acoustic wave are close to the harmonics of the experimental duct. On the other hand, the acoustic oscillations were damped when the frequencies of the pressure oscillations are away from the harmonics of the duct.
This research is concerned with the study of sound generation by simulated solid rocket premixed flames located on the sidewall of a long rectangular duct. Specifically, the flame radiation, i.e., light emission, of the flame and the induced acoustic oscillation were investigated. These studies reveal that the self-excited oscillatory flame radiation and the induced pressure oscillation were observed only at certain equivalence ratios. In addition, the flame oscillates with several frequencies and the dominating frequency can be different from that of the induced pressure oscillations. The frequencies of the flame oscillation decreased as the equivalence ratio decreased, and were not affected by the presence of acoustic wave. However, the acoustic oscillations could be enhanced or damped by the flame oscillation depending on the frequency of the oscillations. Driving of acoustic wave occurred when the frequencies of the induced acoustic wave are close to the harmonics of the experimental duct. On the other hand, the acoustic oscillations were damped when the frequencies of the pressure oscillations are away from the harmonics of the duct. |
