Investigation on three mixing enhancement strategies in transverse gaseous injection flow fields: A numerical study.

Highlights • Mixing augmentation mechanisms of three devices were analyzed and compared. • Streamwise vorticity induced by additional vorticity is the main reason for mixing enhancement. • Stagnation pressure loss induced by the pulsed jet is small. • Air jet enhances mixing and reduces the hydrogen distribution on the bottom. • Ramp has a highly remarkable improvement on mixing efficiency and penetration depth. Abstract Numerical investigation of some mixing enhancement strategies based on the traditional transverse injection technique proposed in recent years was carried out by means of the three-dimensional Reynolds-average Navier–Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model. The numerical approaches employed in the current study were validated against the available two- and three-dimensional data in the open literature, and they can be used with confidence to achieve a better understanding of mixing augmentation mechanisms in transverse injection flow fields with various mixing enhancement strategies, namely the pulsed jet, the air jet and the ramp. Results obtained in this study provide important insight into complex flow phenomena. Various fundamental mechanisms dictating the intricate flow characteristics for the transverse injection flow field with various mixing enhancement strategies, including the circulation, vertical structures, velocity vectors and shock wave systems, have been analyzed systematically. The performance parameters of the transverse injection flow fields, such as the mixing length, the fuel penetration depth and the stagnation pressure loss have been compared. Different mixing enhancement strategies have their advantages and disadvantages, and the combination of various mixing enhancement strategies may be a promising injection strategy for better mixing performance of the transverse injection flow field. A stronger streamwise vorticity is the main reason for the mixing enhancement. However, the mixing length and the stagnation pressure loss of the transverse injection flow field show opposite trends from each other with a variance in the intensity of streamwise vorticity. [ABSTRACT FROM AUTHOR]