| 摘要: | 本研究是以開放式的傾斜滑槽作為實驗設備，並在滑槽中設置兩個圓柱形的阻礙物以實驗的方式探討不同實驗控制參數(滑槽傾斜角、圓柱間距)，對超臨界顆粒流撞擊阻礙物後產生的震波交互影響。為了觀察流體在自由表面的速度，攝影機垂直於滑槽上方拍攝影像，並利用粒子影像測速(Particle image velocimetry, PIV)計算速度場，而流體深度則是使用雷射掃描儀搭配旋轉編碼器來量測。實驗結果分析了流體深度、平均速度、擾動速度、粒子溫度以及福祿數的變化，根據這些分析參數的結果，建立了參數彼此之間的關聯性。
由實驗結果可以知道，顆粒經過震波後會有流體深度突然上升以及速度突然下降的不連續變化，當兩個震波彼此交互影響時，流體深度會上升得更高，影響範圍也變得更遠。在低傾斜角時，我們發現最大流體深度、平均擾動速度以及平均粒子溫度是隨著圓柱間距增加而減小，反之，在高傾斜角時，是隨著圓柱間距增加而增加。表示流場擾動速度與粒子溫度的增加會導致顆粒的流動變得稀薄，影響流體深度的膨脹效應越強，使最大流體深度增加。最後，我們從流場的深度剖面發現不同實驗組別間，有著不同的流動形態，並將所有組別的結果繪製成相圖呈現，還發現流動形態與最小福祿數有關。
;This study investigates the interaction effects of shock waves between two circular cylinder obstacles in supercritical granular flow using an open inclined chute as the experimental equipment. Different experimental control parameters, such as the inclination angle of the chute and the spacing between the cylinders, are used to investigate the shock wave interaction after the granular media impacts obstacles. A camera perpendicular to the surface of the chute will be used to record the free surface granular flow images, and particle image velocimetry (PIV) is employed to calculate the velocity fields. The fluid depth is measured using a laser scanner combined with an encoder. The experimental results analyze the variations in fluid depth, mean velocity, fluctuation velocity, granular temperature, and Froude number. According to these analysis parameters, we also established correlations between each other.
From the results, it is observed that the granular flow experience discontinuous changes in fluid depth with sudden increases and decreases in velocity after shock waves. When two shock waves interact with each other, the fluid depth increases even higher, and the influence range becomes larger. At low inclination angles, the maximum fluid depth, average fluctuation velocity, and average granular temperature decrease with the increase in cylinder spacing. Conversely, at high inclination angles, these parameters increase with increasing cylinder spacing. The results show that the increase in fluctuation velocity and granular temperature will cause the granular flow field to become dilute. The expansion behavior of the fluid will further increase the maximum fluid depth. Finally, we identified different flow types from the depth profile of the flow field. It can be seen from the phase diagram that the flow type is related to the minimum Froude number. |
