Particle Dynamic Trajectory Measurement Method Based On Asynchronous Delay Method

Particle tracking velocimetry is a measurement technology that tracks the trajectory of single particles.It is a commonly used technology in the field of particle two-phase flow measurement.Light-field cameras based on light-field imaging technology can record light information in space,and a single camera can be used to measure three-dimensional information in space,which has gradually become a research focus and focus in many fields.In the field of particle two-phase flow measurement,research on three-dimensional particle tracking and speed measurement technology based on light field camera imaging system is currently in its infancy in China.Aiming at the low frame rate caused by the long transmission time of single frame image data reading in the light field camera,this paper proposes an image acquisition method based on asynchronous delay sampling mode.When a light field camera is used to capture images of moving particles in a flow field,referring to the higher frame rate overlap sampling mode of a single conventional camera,two identical light field cameras are used to perform image acquisition based on asynchronous timing,and the delay of adjacent frame image acquisition is delayed.The time can be adjusted according to the actual situation,breaking the limitation of the light field camera low frame problem in the 3D particle tracking velocimetry technology.Aiming at the problem of slow speed of light field camera 3D reconstruction,this paper proposes a 3D particle positioning method based on an optimized multiplication algebraic reconstruction algorithm.In-depth study of the light field imaging model of three-dimensional particles in space,and the imaging model of particles in the light field camera is determined by establishing a ray tracing matrix.Establishment of mathematical model based on light field camera tomography reconstruction,calculation of light field image,reconstruction using multiplication algebra.The algorithm reconstructs the particle position,optimizes the weight matrix and relaxation factor of the algorithm,and improves the speed and accuracy of particle reconstruction positioning.Finally,a light field camera particle tracking measurement system based on asynchronous time-lapse sampling was established.Particle tracking velocity measurement technology was used to measure particles in the flow field.The light field camera was used to collect particle images and perform 3D reconstruction spatial positioning and trajectory measurement.The particle size and speed of the particles are obtained by processing.