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

任意形状颗粒的尺寸测量具有技术意义，并且准确测定其当量直径是重要的，因为工业过程中的大多数颗粒是非球形的。为了提高设备的使用效率，需要一种可靠的测量技术。一般来说，流体中非球形颗粒的运动受阻力和惯性力的控制。由于缺乏有效的测量技术，非球形颗粒的当量直径的评估是不相关的。本研究的目的是发展流场中非球形颗粒的测量技术，建立一套合适的信号处理技术，提供颗粒的速度、尺寸、形状、姿态和轨迹。测量是在自由下落流和受限射流的情况下进行的。通过实验研究了非球形度对颗粒分散性的影响，并对本系统的性能和精度进行了评价。 ...更多信息 该仪器由激光多普勒测速仪、接收光学系统和阴影图像处理单元组成，在测量体积的焦平面上放置线性光传感器阵列。阵列以预定义的采样频率对移动的二维阴影的一维切片进行采样。二维阴影图像的重建使用的时间序列的三维切片和同时测量的粒子速度。根据所提供的阴影面积确定粒度。尺寸的测量精度估计为约3%的球形颗粒和10%的非球形颗粒。在雷诺数为14700的受限射流中，测量了颗粒的二分量速度、尺寸和数密度，实验结果表明，非球形颗粒的平均速度轴向分量小于球形颗粒，球形颗粒的平均速度轴向分量与球形颗粒的平均速度轴向分量基本相同，非球形颗粒的径向均方位移大于球形颗粒的径向均方位移。结果表明，非球形颗粒在射流下游的运动方式与球形颗粒不同，非球形颗粒在射流中的停留时间越长，径向弥散越大。少

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