In this study, experiments were carried out to investigate the detonation velocity behavior near limits in rough-walled tubes. The wall roughness was introduced by using different spiral inserts in 76.2-mm-diameter, 50.8-mm-diameter, 38.1-mm-diameter, and 25.4-mm-diameter tubes. Different pre-mixed mixtures, CH4 + 2O2, C2H2 + 2.5O2, C2H2 + 2.5O2 + 70%Ar, and 2H2 + O2 were tested in the experiments. Different spiral wire diameters were used, and the pitch of each spiral was twice of the diameter to keep the same level of roughness in all experiments for each tube. Fiber optics were used to record the detonation time of arrival to deduce the velocity. The normalized velocity V/VCJ and the velocity deficit δ were computed and analyzed to describe the detonation behavior near the limit. The cellular structure near the limit was recorded by the smoked foils.

中文翻译：

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近极限气态爆轰在粗糙壁管中的传播

在这项研究中，进行了实验以研究在粗糙壁管中接近极限的爆速行为。通过在 76.2 毫米直径、50.8 毫米直径、38.1 毫米直径和 25.4 毫米直径的管中使用不同的螺旋插入件来引入壁粗糙度。在实验中测试了不同的预混合混合物 CH4 + 2O2、C2H2 + 2.5O2、C2H2 + 2.5O2 + 70%Ar 和 2H2 + O2。使用了不同的螺旋线直径，每个螺旋线的节距是直径的两倍，以在每个管的所有实验中保持相同的粗糙度水平。使用光纤记录到达的爆炸时间以推导出速度。计算和分析归一化速度 V/VCJ 和速度赤字 δ 以描述接近极限的爆轰行为。