标题： 通过条纹角度可视化检测颗粒管道流中的湍流模式 显示英文标题

标题： Detecting Turbulent Patterns in Particulate Pipe Flow by Streak Angle Visualization

摘要： 在颗粒管道系统中检测层流到湍流的过渡仍然是流体力学中的一个复杂问题，通常需要复杂且昂贵的实验设备。 本研究提出了一种创新的条纹可视化方法，旨在提供一种简单且可靠的方法，以识别具有中性浮力颗粒的颗粒管道流中的过渡湍流模式。 该技术采用激光装置和低成本的相机设置来捕捉流体中的粒子生成的条纹，从而实现实时观察流动模式。 通过与已建立的技术如粒子图像测速（PIV）和压降测量进行比较，验证了所提出方法的准确性与可靠性。 实验表明，该条纹可视化方法通过分析条纹角度的标准差，能够区分层流、过渡流和湍流区域。 该方法在低颗粒浓度下尤其高效，即在其他更成熟的方法变得不那么有效的地方。 此外，该技术使我们能够利用基于条纹角度统计分布的Kullback-Leibler散度确定临界雷诺数，这与以往的研究结果一致。 由于在低浓度下有效且稳健，这种条纹可视化技术为颗粒管道流的表征开辟了新的前景，不仅限于实验室环境，还包括工业多相流等不太受控的场景，在这些场景中确定流动的层流或湍流性质是流量计校准的前提条件。 显示英文摘要

摘要： Detecting the transition from laminar to turbulent flow in particulate pipe systems remains a complex issue in fluid dynamics, often requiring sophisticated and costly experimental apparatus. This research presents an innovative streak visualization method designed to offer a simple and robust approach to identify transitional turbulent patterns in particulate pipe flows with neutrally buoyant particles. The technique employs a laser arrangement and a low-cost camera setup to capture particle-generated streaks within the fluid, enabling real-time observation of flow patterns. Validation of the proposed method was conducted through comparison with established techniques like Particle Image Velocimetry (PIV) and pressure drop measurements, confirming its accuracy and reliability. Experiments demonstrate the streak visualization method's capacity to differentiate between laminar, transitional, and turbulent flow regimes by analyzing the standard deviation of streak angles. The method is especially efficient at low particle concentration, ie precisely where other more established methods become less effective. Furthermore, this technique enables us to identify a critical Reynolds number using Kullback-Leibler divergence built on the statistical distribution of streak angles, which is consistent with previous studies. Because it is effective at low concentrations and robust, this streak visualization technique opens new perspectives for the characterization of particulate pipe flows not only in the confines of the laboratory but also in less controlled industrial multi-phase flows where determining the laminar or turbulent nature of the flow is a prerequisite for flowmeter calibration.