Abstract Due to their low sedimentation rate, nano-objects offer the opportunity to study flame propagation at low turbulence. The burning velocity was then estimated by flame visualization in two apparatuses: a vertical 1 m long tube with a square cross-section and a 20 L sphere equipped with visualization windows and a vent. This works aims to study the laminar burning velocity of nanocellulose by a direct visualization of the flame propagation within these devices. A high-speed video camera was used to record the flame propagation, and an estimation of the unstretched burning velocity was obtained through linear and nonlinear relationships relating the flame stretching and the flame velocities. Although these methods were initially established for gases, the organic nature of nanocellulose implies a fast devolatilization, which makes the application of the methods possible in this work. Similar results were obtained in both apparatuses in different turbulence conditions, proving the laminar burning velocity was approached. The laminar burning velocity for the nanocellulose was determined to be 21 cm s−1. This value, estimated through flame propagation visualization, was then compared to the value calculated by applying a semi-empiric correlation to the pressure-time evolution recorded during standard explosion tests in the 20 L vessel.

中文翻译：

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“敲击纳米纤维素”：接近粉末空气火焰的层流燃烧速度

摘要 由于纳米物体的低沉降率，为研究低湍流下的火焰传播提供了机会。然后通过两种装置中的火焰可视化估计燃烧速度：具有方形横截面的垂直 1 m 长管和配备有可视化窗口和通风口的 20 L 球体。这项工作旨在通过直接可视化这些设备内的火焰传播来研究纳米纤维素的层流燃烧速度。使用高速摄像机记录火焰传播，并通过与火焰拉伸和火焰速度相关的线性和非线性关系获得未拉伸燃烧速度的估计。虽然这些方法最初是针对气体建立的，但纳米纤维素的有机性质意味着快速脱挥发分，这使得这些方法在这项工作中的应用成为可能。两种装置在不同湍流条件下都获得了相似的结果，证明接近层流燃烧速度。纳米纤维素的层流燃烧速度确定为 21 cm s-1。该值是通过火焰传播可视化估算的，然后与通过将半经验相关性应用于 20 L 容器中标准爆炸测试期间记录的压力-时间演变计算的值进行比较。