Numerical investigation on the flow structures in a narrow confined channel with staggered jet array arrangement

A series of numerical analyses have been performed to investigate the flow structures in a narrow confined channel with 12 staggered circular impingement holes and one bigger exit hole. The flow enters the channel through the impingement holes and exits through the far end outlet. The flow fields corresponding to two jet Reynolds numbers （25000 and 65000） and three channel con- figurations with different ratios of the channel height to the impingement hole diameter （Zr 1, 3, 5） are analyzed by solving the Reynolds averaged Navier-Stokes equations with the realizable k-e turbulence model. Detailed flow field information including the secondary flow, the interaction between the jets and the cross flow, and flow distribution along the channel has been obtained. Comparisons between the numerical and experimental results of the flow fields at the four planes along the channel are performed to validate the numerical method. The calculated impingement pattern, high velocity flow distribution, low velocity separation region and vortices are in good agreement with the experimental data, implying the validity and effectiveness of the employed numerical approach for analyzing relevant flow field.

Preparation of SGO-modified nanofiltration membrane and its application in SO_4^(2-) and Cl^- separation in salt treatment

The lack of fresh water in the world makes the search for an effective method to decontaminate water an urgent priority.An important step is to remove different multivalent ions in salt treatment.Nanofiltration(NF)has been used for treating water containing different kinds of salts.In this work,sulfonate group-modified graphene oxide(SGO)was prepared,and added during the interfacial polymerization(IP)reaction to prepare SGO-modifiedNF membranes(PA-SGO).The chemical composition,structure and surface properties of PA and PA-SGO membranes were characterized by FT-IR,XPS,SEM,AFM,contact angle and zeta potential measurements.Their water flux,salt rejection and antifouling abilities were investigated systematically.The testing results showed that the water flux of PA-SGO(0.03%SGO)was 45.85 LMH under a pressure of 0.2 MPa,and the salt rejection varied in the order of Na_2SO_4(98.99%)>MgSO_4(91.25%)>MgCl_2(42.27%)>NaCl(21.96%).An anti-fouling experiment indicated that the PA-SGO membrane had good anti-fouling properties because of its decreased roughness and increased hydrophilicity and electronegativity.The PA-SGO membrane has good potential for use in removing salt ions from water.

Experimental and numerical study of a gas cyclone with a central filter

This paper studies a novel gas cyclone with a cylindrical fiter face installed in the center from the vortex finder to the bottom hopper.The experimental results show that this composite cyclone has a higher collection fficiency and a lower pressure drop than the original cyclone.The mechanisms for the improvement are analyzed by both physical experiments and numerical simulations.By measuring dust samples collected at different places it is revealed that the center filter can prevent fine particles from entering the inner vortex and escaping,which accounts for the increase of the collection eficiency.In addition,the flow field of the composite cyclone is simulated by computational fluid dynamics and compared with that of the original cyclone.The analysis shows that with the filter layer installed,the swirling flow disappears in the vortex finder,which decreases the kinetic energy dissipation and hence lowers the pressure drop.