Abstract The flame propagation characteristics of hydrogen/methane/air mixtures with different hydrogen addition ratios (φ = 0, 10 %, 20 %, 30 %, 40 % and 50 %) in different variable cross-section ducts were studied. A high-speed camera and pressure sensors were used to collect flame images and determine the overpressure dynamics. The results show that the smooth flame front will be twisted and folded, when the flame propagates to the abrupt position of the cross-section area of the duct. The larger the abrupt change rate of the duct cross-section is, the more obvious the disturbance to the flame and the more severe the turbulence. With increasing hydrogen addition ratio, the flame propagation speed and overpressure in the four kinds of variable cross-section ducts studied increase. The time for the flame front to reach the downstream end is gradually shortened, and the flame propagation time when the flame propagates from the smaller cross-section tube to the larger cross-section tube is more severely shortened with increasing hydrogen addition ratio than that when the flame propagates from the larger cross-section tube to the smaller cross-section tube. The increase of the overpressure caused by the addition of hydrogen is more significant when the flame propagates from the smaller cross-section tube to the larger cross-section tube. When the flame propagates from the smaller cross-section tube to the larger cross-section tube or from the larger cross-section tube to the smaller cross-section tube, the larger the abrupt change rate of the duct cross-section is, the larger the maximum overpressure.

中文翻译：

---

氢气/甲烷/空气预混火焰在变截面管道中的传播特性研究

摘要 研究了不同加氢比（φ=0、10%、20%、30%、40%和50%）的氢气/甲烷/空气混合物在不同变截面管道中的火焰传播特性。高速摄像机和压力传感器用于收集火焰图像并确定超压动态。结果表明，当火焰传播到管道横截面的突变位置时，光滑的火焰前沿会发生扭曲和折叠。风道截面突变率越大，对火焰的扰动越明显，湍流越剧烈。随着加氢比的增加，所研究的四种变截面管道中的火焰传播速度和超压均增加。火焰前端到达下游端的时间逐渐缩短，火焰从较小截面管传播到较大截面管时的火焰传播时间随着加氢比的增加而明显缩短。火焰从较大横截面的管子传播到较小横截面的管子。当火焰从较小截面的管子传播到较大截面的管子时，加氢引起的超压增加更为显着。当火焰从小截面管传播到大截面管或从大截面管传播到小截面管时，管道截面的突变率越大，则越大。最大超压。火焰从小截面管传播到大截面管时的火焰传播时间随着加氢比的增加比火焰从大截面管传播到小截面管时明显缩短。节管。当火焰从较小截面的管子传播到较大截面的管子时，加氢引起的超压增加更为显着。当火焰从小截面管传播到大截面管或从大截面管传播到小截面管时，管道截面的突变率越大，则越大。最大超压。火焰从小截面管传播到大截面管时的火焰传播时间随着加氢比的增加比火焰从大截面管传播到小截面管时明显缩短。节管。当火焰从较小截面的管子传播到较大截面的管子时，加氢引起的超压增加更为显着。当火焰从小截面管传播到大截面管或从大截面管传播到小截面管时，管道截面的突变率越大，则越大。最大超压。