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CFD simulation of a vortex-controlled diffuser for a jet engine burner

Chijioke Emeka Gaius, Teodorczyk Andrzej

Combustion Engines

2023

R. 62, nr 4

71--82

A computational flow analysis of an ideal vortex-controlled diffuser (VCD) was carried out. The simulation model used is the compressible Reynolds averaged Navier-Stokes equations(RANS), with the application of the RNG based k-ε turbulence model. The effects of important parameters like static pressure recovery, bleed fraction, position of bleed slot, have been studied and comparisons were made with respect to VCD without the bleed configuration and the following features were revealed: radial profiles of velocity at inlet, mid-planes and exit planes, including diffuser effectiveness (i.e. static pressure recovery), diffuser efficiency, reattachment length and diffuser total pressure loss. Results obtained by applying the RNG turbulence model show an instantaneous improvement in the diffuser efficiency that happen at reasonably minimal suction rates. From the calculations, it has been verified and shown in the analysis that the effect of the bleed positioning offers advantages in relation to where it is located.

Numerical Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel

Saleem Bala Kawa M., Mustafa Andam, Kareem Dalshad Ahmed, Yuce Mehmet Ishak, Szydłowski Micchał, Al-Ansari Nadhir

Archives of Hydro-Engineering and Environmental Mechanics

2023

Vol. 70, nr 1

49--69

Computational examinations of the flow field in an open channel having a single Backward- -Facing Step (BFS) with a constant water depth of 1.5 m were performed. The effects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two different expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic (CFD) simulations. Commercially available CFD software, ANSYS FLUENT, was used for calculations. The simulation outcomes were verified using experimental results. Moreover, analyses were performed by using two equation turbulence closure models, K-ε family (standard, RNG and realizable), and K-ω family (Wilcox’s and SST K-ω). The analyses have revealed that the reattachment length increases with an increase in the expansion ratio, the flow velocity and the Reynolds number. The results obtained for two expansion rates and eight different flow velocities have shown insignificant differences between one turbulence closure model and the others. Furthermore, it was observed that both velocity and expansion ratios have an effect on the reattachment zone size.