Development of Simultaneous Non-intrusive Measurement of Size, Flowing Attitude and Velocity of Arbitrarily Shaped Particle.

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The sizing of arbitrarily shaped particles is of technical interest and accurate determination of their equivalent diameter is important, because most particles in industrial processes are non-spherical. A reliable measuring technique has been demanded for improvement of equipment with high efficiency. In general, motion of non-spherical particle in fluid is governed by drag and inertia forces. The evaluation of equivalent diameter of non-spherical particle is not relevant due to the lack of effective measuring techniques. The purpose of the present investigation is to develop the measuring technique for non-spherical particles in flow and to establish a suitable signal processing technique, which provided velocity, size shape, and attitude and trajectory of particle. The measurements were implemented with free falling flow and confined jet flow. The effect of non-sphericality on particle dispersion was presented by these experiments, and also the performance and accuracy of the presen … More t technique were confirmed by the practical application.The present instrument consisted of a Laser Doppler Velocimeter and a receiving optics and a shadow image processor unit with a linear photo sensor array placed at the focal plane corresponding to the measuring volume. The array sampled one-dimensional slices of moving two-dimensional shadow at the pre-defined sampling frequency. The time series of the on-dimensional slices and the simultaneously measured particle velocity were used for reconstruction of the two-dimensional shadow image. From the provided shadow area the particle size was determined. Measurement accuracy of sizing was estimated at about 3% for spherical particles and 10% for non-spherical particles. The measuring system also provided spatial position of a particle traveling through the measuring volume.The experiments in a confined jet flow with Reynolds number of 14700, in which two-component velocities, size and number density of particle were measured, indicated that the axial component of mean velocities of non-spherical particle was smaller than that of spherical particle which had a almost same terminal velocity, and that radial mean square displacement of non-spherical sarticles estimated form their number density measurements was larger than that of spherical particles. It was concluded from the results that non-spherical particle behaved differently form spherical particles in downstream of the jet, and longer resident time of non-spherical particle in the jet flow caused larger radial dispersion. Less