Experimental study on three dimensional movements of particles II Effects of particle diameter on turbulence characteristics
Abstract Based on the 3D PTV (Particle Tracking Velocimetry) measuring system, the 3D movement characteristics of particles with four different diameters were investigated. Under specific flow conditions, the impact of particle diameters on 3D motion of particles was studied, and the turbulence characteristics were analyzed by different statistical methods. The results showed that the turbulence intensity of coarse particle decreased as the diameter increased. In near wall region, the probability density distributions of longitudinal and vertical fluctuation velocities both deviated from the normal distribution; while in the outer region, the probability density distribution of vertical fluctuation velocity approximately agreed with the normal distribution.
Summary First a short analysis and description is given about the profile geometry of special twist drill. Different groups of profiles are defined. The influence of the cross section profile to the torsional stiffness was determined and related to the drilling process. Torque and thrust were measured under variation of speed, feed, depth and point geometry. Testing the different dynamic behaviour of the twist drills is included.