Design and application of an algorithm for measuring particle velocity based on multiple characteristics of a particle

Abstract During the post-processing of PIA images, correctly pairing the particles in two frames is the basic premise underlying the accurate measurement of particle velocity. The traditional particle pairing algorithm is designed according to the characteristics of particle morphology, but this method could result in a considerable number of wrong pairings when dealing with areas having particles of large density and similar shape, thus, calculate the particle velocities incorrectly. In this paper, the behavior characteristics of particles are analysed, and a new particle pairing algorithm based on multiple characteristics of a particle is proposed. In this algorithm, the similarities of basic particle features, adjacent particle motion directions and particle neighbourhood space are considered and analysed. A brand-new formula is established to calculate the overall feature similarity of the pairing particle and each searching particle. After the particles in two frames are paired, the particle velocities can be calculated. In this paper, the new algorithm was used to measure the particle velocity under high ambient pressure and cross flow respectively. The particle velocity is similarly to normally distribution. In D(40), the particles with the velocity of 0.8–0.9 m/s are the most, and in D(60), the particles with velocity of 1.6–1.7 m/s are the most, The mean velocity of particles at C(10,25) is 60.07 m/s. In C(20,50), the mean particle velocity is 52.01 m/s. The experimental results show that the new algorithm has a high precision rate of particle pairing, and can accurately measure particle velocities under different experimental conditions.