Measuring the coefficient of restitution of high speed microparticle impacts using a PTV and CFD hybrid technique

Abstract

A novel particle tracking velocimetry (PTV)/computational fluid dynamics (CFD) hybrid method for measuring coefficient of restitution (COR) has been developed which is relatively simple, cost-effective, and robust. A laser and camera system is used in the Virginia Tech Aerothermal Rig to measure velocity trajectories of microparticles. The method solves for particle impact velocity at the impact surface using a CFD solution and Lagrangian particle tracking. The methodology presented here attempts to characterize a difficult problem by a combination of established techniques, PTV and CFD, which have not been used in this capacity before. Erosion and deposition are functions of particle/wall interactions and COR is a fundamental property of these interactions. COR depends on impact velocity, angle of impact, temperature, particle composition, and wall material. Two sizes of Arizona road dust and one size of glass beads are impacted on to a 304 stainless steel coupon. The particles are entrained into a free jet of 27 m s−1 at room temperature. Impact angle was varied from 85° to 25° depending on particle. Mean results collected using this new technique compare favorably with trends established in literature. The utilization of this technique to measure COR of microparticle sand will help develop a computational model and serve as a baseline for further measurements at elevated air and wall temperatures.

A regime map for the normal surface impact of wet and dry agglomerates

“…The physical properties of the dust particles and the glass walls are shown in Table . Reagle et al have measured the coefficient of restitution (COR) for oblique impacts of Arizona test dust (ATD) particles with nominal size 20–40 µm. In the mentioned study, the impact angle was varied between 30° and 80° and the measured COR ranged from 0.9 to 0.4.…”

Vibrational Effects on the Coefficient of Restitution

“…LASER Doppler Velocimetry [26],Particle Tracking Velocimetry [27] amongst others. The most prominent technique is measuring the time lag between consecutive impacts [28,29].…”

Multi-fidelity uncertainty quantification of particle deposition in turbulent pipe flow

“…It remains an ongoing debate in the literature how to parametrize and measure cohesive forces accurately [70,71,72]. As summarized in [41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68] of common natural particulates and dust constituents. Upper and lower bounds correspond to the 10-th and 90-th percentile when distributions are given.…”