A gas explosion is often vented to a safe location by means of a discharge duct. However, the presence of a discharge duct increases the explosion severity in the vessel, inducing a higher explosion overpressure compared to a simply vented vessel. To reduce the explosion overpressure in the vessel, an experimental study was performed to suppress the methane-air explosions in a 5 L vessel connected to a discharge duct of different scales (e.g., length and diameter) and with various sodium bicarbonate concentrations. The results show that the initial flame propagation process in the vessel was basically similar in the simply vented vessel and in the vessel vented through a discharge duct (i.e., ducted-vessel). In the middle and late stages of flame propagation in the vessel, the flame fragmentation was more pronounced for the ducted-vessel. Moreover, the degree of flame fragmentation in the vessel increased with the duct length. The flame structure in the vessel was more irregular for a larger vent coefficient (K_v = 9.75). The more pronounced quenching in the short duct (250 mm duct) is related to the high inhibition efficiency due to the leakage of a large amount of sodium bicarbonate (SBC) powder into the discharge duct while in the long duct (750 mm duct) the disturbance is due to the strong turbulence. The appropriate SBC concentration can transform the mechanism for the pressure rise in the vessel. At low powder concentrations the maximum pressure in the vessel is dictated by the flame reaching the vessel wall, while at high concentrations the maximum pressure is dominated by the pressure (i.e., burn-up) in the discharge duct. There is an approximately linear correlation between the maximum pressure and the average flame velocity in the discharge duct for a given powder concentration, and a linear relationship between the maximum pressure in the vessel and the duct independent of the SBC concentration. Through the analysis of the flame dynamics (e.g. flame morphology, flame propagation velocity and turbulence) and friction resistance induced by the varying duct scales, the suppression efficiency of SBC powder in the vessel is higher for a longer and narrower discharge duct.

瓦斯爆炸通常通过排气管排放到安全位置。但是，排气管的存在增加了容器内爆炸的严重性，与简单通风的容器相比，导致更高的爆炸超压。为了减少容器中的爆炸超压，进行了一项实验研究，以抑制5 L容器中的甲烷-空气爆炸，该容器连接到不同规模（例如长度和直径）且具有各种碳酸氢钠浓度的排放管。结果表明，容器中的初始火焰传播过程在简单通风的容器中以及通过排放导管（即导管）通风的容器中基本相似。在容器中火焰传播的中期和后期，导管容器的火焰破碎更为明显。而且，容器中火焰的破碎程度随管道长度的增加而增加。对于更大的排气系数，容器中的火焰结构更加不规则（ķ _v= 9.75）。短导管（250 mm导管）中更明显的淬火与抑制效率高有关，这是由于大量碳酸氢钠（SBC）粉末泄漏到排放导管中，而长导管（750 mm导管）中则有较高的抑制效率。扰动是由于强烈的湍流。适当的SBC浓度可以改变容器内压力升高的机制。在低粉末浓度下，容器中的最大压力由到达容器壁的火焰决定，而在高浓度下，最大压力由排放管道中的压力（即燃尽）决定。对于给定的粉末浓度，最大压力与排放管道中的平均火焰速度之间存在近似线性关系，以及容器中最大压力与管道之间的线性关系与SBC浓度无关。通过分析不同管道尺寸引起的火焰动力学（例如，火焰形态，火焰传播速度和湍流）和摩擦阻力，对于更长，更窄的排出管道，容器中SBC粉的抑制效率更高。