Numerical evaluation of stresses acting on particles in high-pressure microsystems using a Reynolds stress model

Effect of ventilation mode and airflow rate on the flow field and particle mass concentration distribution of a high-speed rail carriage in the putty polishing workshop

Objectives. The putty polishing procedure usually produces a large number of micron-sized particles, which can lead to serious respiratory diseases as well as skin conditions. The diagonal ventilation system is widely used to decrease the particle concentration in different environments. However, it becomes less effective for a large empty factory workshop, such as the polishing workshop for high-speed rail carriages, in which the diagonal ventilation mode usually results in turbulence in the airflow. In this article we report that the situation can be improved by optimizing the number and locations of the air inlets and outlets in the carriage-polishing workshop. Three modified ventilation modes are proposed, whose efficiencies are evaluated by numerical simulations and compared to the diagonal mode. Results. The results show that the mode with two inlets close to the ceiling and two outlets close to the floor yields the best performance. Besides, the optimum airflow rate under this mode is further determined by both simulations and in-situ measurements. The results reported can serve as a reference for the design of the ventilation systems in the polishing workshops of similar sizes.

Implicit Large Eddy Simulation of Flow in a Micro-Orifice with the Cumulant Lattice Boltzmann Method

A detailed numerical study of turbulent flow through a micro-orifice is presented in this work. The flow becomes turbulent due to the orifice at the considered Reynolds numbers (∼ 10 4 ). The obtained flow rates are in good agreement with the experimental measurements. The discharge coefficient and the pressure loss are presented for two input pressures. The laminar stress and the generated turbulent stresses are investigated in detail, and the location of the vena contracta is quantitatively reproduced.

Delamination of graphite in a high pressure homogenizer

A scalable industrial method for graphene and Few-Layer-Graphene (FLG) production by graphite delamination in N-methylpyrrolidone and water–surfactant mixtures using a high pressure homogenizer is presented.