Steady-state and unsteady Reynolds-averaged Navier-stokes modelling of cold jets-in-hot crossflow in a cylindrical duct for non-impinging, impinging, and strongly impinging jets

Kartaev, E. V.; Holdeman, J. D.

doi:10.1007/s00231-020-02853-6

Cited by 2 publications

(1 citation statement)

References 25 publications

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“…5 Beyond the early attempts at understanding the basic mixing and flow field characteristics with cross flow jets, 6 more recent studies have addressed the influence of preheating such jets on NO x emissions 7 as well as the likely impact on instabilities. 8 In the case of fixed bed biomass combustors, the main flow primary air, passing through the packed fuel bed is further supplemented in the downstream with secondary air, thus resulting in a configuration involving jets in a cross-flow. 9 The role of secondary air in biomass combustion becomes very important due to high volatile matter content of biomass, which requires a further supply of air at the second stage above the fuel bed.…”

Section: Introductionmentioning

confidence: 99%

Secondary air induced flow structures and mixing in a fixed bed combustor

Junejo

Chapela

Porteiro

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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Air staging features widely in biomass combustion from small space heaters to industrial-scale moving grate systems. Whilst studies have been conducted into the impact of air staging on emissions and combustion performance, there is little or no insight into the exact flow dynamic and physical mechanisms that are induced by secondary air under such conditions. This paper uses experimental data to validate numerical predictions before investigating the flow field structures and mixing characteristics in a fixed bed air staged combustor. The study utilizes Constant Temperature Anemometry (CTA) experiments to establish boundary conditions for a lab-scale fixed bed combustor. Results from numerical simulations obtained using [Formula: see text] l- 𝜔 model were in good agreement with experimental data. Conditions tested cover five different secondary to total air ratios (Qs/Qt) and two different locations of secondary air injection. Results show that at Qs/Qt = 0.50, 0.25 and 0.18 one strong recirculation zone is induced upstream of the secondary air injection and one downstream. Varying the point of injection of secondary air from h/D = 0.64 to h/D = 0.40 also had an effect on the size of the upstream recirculation zone. Qs/Qt = 0.50 had the highest values of mixing index among all spatially located planes at the upstream of secondary air injection. The overall findings shed light on the possible flow interactions between secondary air and the top layers of fuel bed. They also highlight the significance of secondary air on inducing both upstream and downstream flow structures.

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Section: Introductionmentioning

confidence: 99%

Secondary air induced flow structures and mixing in a fixed bed combustor

Junejo

Chapela

Porteiro

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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Comparison between sonic jets with one jet orifice and two opposite orifices into a Ma-3.0 supersonic crossflow through circular ducts

2022

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Large-eddy simulations and nanoparticle-based planar laser scattering experiments are conducted to investigate various physical aspects of transverse sonic jets injected into a Ma-3.0 supersonic crossflow through a circular pipe. Configurations with one jet and two opposite jets are compared. For the single jet, a separation shock is generated by the recirculation zone on the opposite wall, and this intersects with the jet shear layer to push several jet plumes into the near-wall region. For the two jets, the bow shocks interact with each other, forming an oblique shock train. All of the shocks promote vortex breakage in jet wakes. A counter-rotating vortex pair is generated in the jet near-field region, enhancing the local mixing. A near-wall region in the jet lee between the counter-rotating vortex pair branches exhibits a low fuel mass fraction. The jet fluid in the downstream near-wall region is entrained by the crossflow upstream of the jet. The interaction between the bow shocks and shear layers of the two jets induces recirculation zones in the lee of the jet, which enhance the fuel mixing. This explains the phenomenon whereby the total pressure recovery coefficient and mixing efficiency of two jets are higher than those of the single jet.

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Steady-state and unsteady Reynolds-averaged Navier-stokes modelling of cold jets-in-hot crossflow in a cylindrical duct for non-impinging, impinging, and strongly impinging jets

Cited by 2 publications

References 25 publications

Secondary air induced flow structures and mixing in a fixed bed combustor

Secondary air induced flow structures and mixing in a fixed bed combustor

Comparison between sonic jets with one jet orifice and two opposite orifices into a Ma-3.0 supersonic crossflow through circular ducts

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