Temperature statistics in a radiatively heated particle-laden turbulent square duct flow

Banko, Andrew; Villafañe, Laura; Kim, Ji Hoon; Eaton, John K.

doi:10.1016/j.ijheatfluidflow.2020.108618

Cited by 17 publications

(11 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our experiments extended from this regime to conditions when inertia should dominate. Still, even at St ∼ 35, the fluid behavior can impact preferential concentration of particles (Banko, 2018). Eruptions can have Stokes numbers extending from <<1 to >>1, depending on which portion of the plume is considered.…”

Section: Experimental Test Parametersmentioning

confidence: 99%

Flow Development and Entrainment in Turbulent Particle‐Laden Jets

et al. 2023

View full text Add to dashboard Cite

Explosive eruptions expel volcanic gases and particles at high pressures and velocities. Within this multiphase fluid, small ash particles affect the flow dynamics, impacting mixing, entrainment, turbulence, and aggregation. To examine the role of turbulent particle behavior, we conducted an analogue experiment using a particle‐laden jet. We used compressed air as the carrier fluid, considering turbulent conditions at Reynolds numbers from approximately 5,000 to 20,000. Two different particles were examined: 14‐μm diameter solid nickel spheres and 13‐μm diameter hollow glass spheres. These resulted in Stokes numbers between 1 and 35 based on the convective scale. The particle mass percentage in the mixture is varied from 0.3% to more than 20%. Based on a 1‐D volcanic plume model, these Stokes numbers and mass loadings corresponded to millimeter‐scale particle diameters at heights of 4–8 km above the vent during large, sustained eruptions. Through particle image velocimetry, we measured the mean flow behavior and the turbulence statistics in the near‐exit region, primarily focusing on the dispersed phase. We show that the flow behavior is dominated by the particle inertia, with high Stokes numbers reducing the entrainment by more than 40%. When applied to volcanic plumes, these results suggest that high‐density particles can greatly increase the probability of column collapse.

show abstract

Section: Experimental Test Parametersmentioning

confidence: 99%

Flow Development and Entrainment in Turbulent Particle‐Laden Jets

et al. 2023

View full text Add to dashboard Cite

show abstract

“…In this way, the turbulent kinetic energy varies non-monotonically as the increasing of radiation intensity due to the competing effects between the downward gravity and the upward buoyancy. Banko et al (2020) investigated experimentally the temperature statistics in the heated particle-laden turbulent square duct flow. The temperature statistics exhibit qualitatively differently at the duct centreline and the near wall under the effect of preferential concentration of particles and the streamwise elongated streaks in the centre and the near-wall regions, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Banko et al. (2020) investigated experimentally the temperature statistics in the heated particle-laden turbulent square duct flow. The temperature statistics exhibit qualitatively differently at the duct centreline and the near wall under the effect of preferential concentration of particles and the streamwise elongated streaks in the centre and the near-wall regions, respectively.…”

Section: Introductionmentioning

confidence: 99%

On the energy transport and heat transfer efficiency in radiatively heated particle-laden Rayleigh–Bénard convection

et al. 2022

View full text Add to dashboard Cite

We investigate the energy transport and heat transfer efficiency in turbulent Rayleigh–Bénard (RB) convection laden with radiatively heated inertial particles. Direct numerical simulations combined with the Lagrangian point-particle mode were carried out in the range of density ratio $854.7\le \rho _p/\rho _0 \le 8547$ and radiation intensity $1\le \phi /\phi _{solar}\le 100$ for both two-dimensional (2-D) and three-dimensional (3-D) simulations. The Rayleigh number ranges from $2\times 10^6$ to $10^8$ for 2-D cases, and is $10^7$ for 3-D cases for $Pr=0.71$ . It is found that particles with small density ratio that encounter strong radiation significantly alter the flow momentum transport and fluid heat transfer, so the fluid temperature of bulk is remarkably heated. We then derived the theoretical relation of the Nusselt number for interphase heat transfer in the heated particle-laden RB convection, which reveals that the heat transfer difference between the top and bottom plates stems from the interphase heat transfer. We further found that both the interphase heat transfer and the interphase thermal energy transport exhibit universal properties. They are both increased linearly with the reciprocal of the normalized density ratio. Additionally, both the interphase heat transfer and the interphase thermal energy transport increase linearly with the increase of radiation intensity. The growth rates exhibit specific scaling relations versus Rayleigh number and density ratio. Two different regimes distinguished by the critical density ratio, i.e. the exothermic particle regime and the endothermic particle regime, are observed. We further derived the power-law relation of the critical density ratios versus Rayleigh number and radiation intensity, i.e. $\rho _p/\rho _c \sim (\phi /\phi _{solar})^{1/2}\,Ra^{1/3}$ , which is in remarkable agreement with the 3-D simulations.

show abstract

“…These experiments reveal that the scaling law of heat flux is very different from the RBC driven by the external temperature difference. Experiments on radiation-absorbing particles in turbulent duct flow reveal the fluid temperature rising and different preferential concentration behaviours at the core region and near the boundary (Banko et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Experiments on radiation-absorbing particles in turbulent duct flow reveal the fluid temperature rising and different preferential concentration behaviours at the core region and near the boundary (Banko et al. 2020).…”

Section: Introductionmentioning

confidence: 99%

Wall-bounded thermal turbulent convection driven by heat-releasing point particles

Yang

2022

J. Fluid Mech.

View full text Add to dashboard Cite

In this work we investigate the thermal convection driven by heat-releasing point particles. Three-dimensional direct numerical simulations are conducted for $1\times 10^7\le {\textit {Ra}} \le 1\times 10^{10}$ and $0.01\le {\textit {St}} \le 10$ , where the Rayleigh number ${\textit {Ra}}$ and Stokes number ${\textit {St}}$ measure the strengths of the heat releasing rate and the Stokes drag, respectively. A regime at intermediate Stokes numbers is identified with most particles accumulating into the top boundary layer region, while for other cases particles are constantly advected over the entire domain. For the latter state, the flow motions are stronger at the upper part of the domain. The thicknesses of both momentum and thermal boundary layers at the top plate follow the same scaling law with ${\textit {Ra}}$ and show minor dependences on ${\textit {St}}$ . The volume-averaged temperature and convective flux exhibit non-monotonic variations as ${\textit {St}}$ increases and reach their minimums at intermediate ${\textit {St}}$ . The fraction coefficient of heat flux, i.e. the ratio between the heat flux through the bottom plate and the total flux through both plates, shares the similar dependence on ${\textit {St}}$ as the convective flux. The relation between these scaling laws can be explained by using the global balance between the dissipation and convective flux. The scaling laws for the transition between different flow regimes are also proposed and agree with the numerical results. The preferential concentration of particles is observed for all cases and is strongest at intermediate Stokes numbers, for which multiscale clustering emerges with small clusters forming larger ones.

show abstract

Temperature statistics in a radiatively heated particle-laden turbulent square duct flow

Cited by 17 publications

References 54 publications

Flow Development and Entrainment in Turbulent Particle‐Laden Jets

Flow Development and Entrainment in Turbulent Particle‐Laden Jets

On the energy transport and heat transfer efficiency in radiatively heated particle-laden Rayleigh–Bénard convection

Wall-bounded thermal turbulent convection driven by heat-releasing point particles

Contact Info

Product

Resources

About