Direct Numerical Simulation and Visualization of Biswirling Jets

Abstract

Two parallel swirling/rotating jets with a distance between them are termed biswirling jets here, which have important and complicated vortex structures different from the single swirling jet due to the negligible vortex-vortex interactions. The visualization of vortex-vortex interaction between the biswirling jets is accomplished by using direct numerical simulation. The evolution of vortex structures of the biswirling jets is found rather complicated. The turbulent kinetic energy and turbulence dissipation in the central convergence region are augmented locally and rather strongly. The modulation of turbulent kinetic energy by jet-jet interaction upon different scales of vortices is dominated by the swirling levels and the distance between the jets. The turbulent kinetic energy upon intermediate and small scale vortices in bijets with not very high swirling level and at a very close distance is smaller than that in single swirling jets, whereas the opposite is true under a far distance, and so forth.

Hydrodynamic Modeling of Turbulence Modulation by Particles in Swirling Gas-Particle Two-Phase Flow

“…combination of swirling number, mass loading, particle size and density etc, which mass loading was considered as the leader order. Moreover, turbulent kinetic energy that determined by the intermediate and the small scale vortices is smaller than of in single swirling jet [21] . Wang et al 2019 [22] studied the effects of inertial particle on self-sustained, turbulent coherent structures in plane Couette flow at low Reynolds number.…”

“…Swirling two-phase hydrodynamics using PDPA were performed by Sommerfield et al 1991,1993 [12,13] . In recent years, the direct numerical simulation (DNS) [18][19][20][21][22][23] , the large eddy simulation (LES) [24][25][26][27][28][29][30][31] , the Reynolds averaged Navier-Stokes simulation (RANS) [32][33][34][35][36][37][38][39][40][41] , have been applied to model and simulate the hydrodynamics of two-phase flows has been rapidly developed based on the computational fluid dynamics (CFD) technique. Gore et al1989 [42] characterized the turbulence modification into augmentation and attenuation categories using a developed intuitive parameter, which is the ratio of the particle diameter to a characteristic size of large eddies.…”

Hydrodynamic Modeling of Turbulence Modulation by Particles in a Swirling Gas–Particle Two-Phase Flow

“… 20 , 21 Low-inertia particles trigger the laminar-to-turbulent instability, whereas high-inertia particles tend to stabilize turbulence due to the extra dissipation induced by particle–fluid coupling. 22 Regarding the LES application, turbulence modulations have strongly anisotropic characteristics and been closely determined by the flow structure in the backward facing step two-phase flows, especially smaller size and lower density particle enhanced the turbulence modulation. 23 For the first time, the swirling particle-laden follows in a coaxial-jet combustor were numerically simulated.…”

Investigations of Gas–Particle Two-Phase Flow in Swirling Combustor by the Particle Stokes Numbers

“…In recent years, computational fluid dynamics (CFD) methods are being utilized substantially compared to hydrodynamic modelling for the single/multicomponent gas-particle two-phase turbulent flow, e.g., the direct numerical simulation (DNS) algorithm [6][7][8][9][10][11], large eddy simulation (LES) SGS model [12][13][14][15][16][17][18], and Reynolds time-averaged Navier-Stokes simulation (RANS) [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Regarding gas turbulence modulations, Gore et al (1989) [35] found that turbulence modifications generally have two kind of effects-that is, the augmentation and attenuation activities-using a dimensionless parameter based on the ratio of particle diameter and length of maximum eddy.…”

“…Meanwhile, gas turbulent modulations are highly sensitive to mass loadings rather than particle response, which is the primary order from a group of parameters: particle size, density, swirling number, etc. Moreover, turbulent kinetic energy of gas is determined by intermediate, smaller-scale vortices [8][9][10]. As for LES SGS modeling, Apte et al (2003) [13] and Oefelein et al (2007) [14] simulated the swirling particle-laden two-phase turbulent flow in a coaxial-jet combustor based on the Sommerfield's experiment [37].…”