Development of a Versatile Aerosol Generation System for Use in a Large Wind Tunnel

Heist, David; Richmond-Bryant, Jennifer; Eisner, Alfred D.; Conner, Teri

doi:10.1080/02786820300947

Cited by 13 publications

(10 citation statements)

References 16 publications

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“…Preliminary spot checking of the symmetry with the cylinder in place supports this assumption. This assumption is also supported by Heist et al [47], which demonstrated that the velocity proÿle was nearly constant (with a coe cient of variation of 3%) over the cross-sectional height of the empty wind tunnel. The same wind tunnel is used in this study.…”

Section: Measurements Takenmentioning

confidence: 57%

“…For a freestream velocity of 1:0 m=s, the tunnel velocity proÿle is uniform over the cross-section with a spatial coe cient of variation of 3.0%; the turbulence intensity at this speed is 3.5%. A detailed description of this tunnel can be found in Reference [47].…”

Section: Wind Tunnelmentioning

confidence: 99%

“…After passing through a contraction, the air encounters a honeycomb grid, which removes any large-scale turbulent structures from the ow. Finally, the air travels downstream to the 1:52 m × 1:21 m × 7:30 m test section where velocity measurements are taken with a two-dimensional 514-nm Argon-Ion laser phase Doppler anemometer (PDA) (Dantec Measurement Technology, Inc., Copenhagen, Denmark), which is described in detail in many publications including [44][45][46][47].…”

Section: Wind Tunnelmentioning

confidence: 99%

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Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Richmond-Bryant¹

2003

Numerical Methods in Fluids

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SUMMARYVeriÿcation testing was performed for various Reynolds-averaged Navier-Stokes methods for uniform ow past a circular cylinder at Re = 5232. The standard and renormalized group (RNG) versions of the k-method were examined, along with the Boussinesq, Speziale and Launder constitutive relationships. Wind tunnel experiments for ow past a circular cylinder were also performed to obtain a comparative data set. Preliminary studies demonstrate poor convergence for the Speziale relationship.Veriÿcation testing with the standard and RNG k-models suggests that the simulations exhibit global monotonic convergence for the Boussinesq models. However, the global order of accuracy of the methods was much lower than the expected order of accuracy of 2. For this reason, pointwise convergence ratios and orders of accuracy were computed to show that not all sampling locations had converged (standard k-model: 19% failed to converge; RNG k-model: 14% failed to converge). When the non-convergent points were removed from consideration, the average orders of accuracy are closer to the expected value (standard k-model: 1.41; RNG k-model: 1.27). Poor iterative and global grid convergence was found for the RNG k-=Launder model. The standard and RNG k-models with the Boussinesq relationship were compared with experimental data and yielded results signiÿcantly di erent from the experiments.

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Section: Measurements Takenmentioning

confidence: 57%

Section: Wind Tunnelmentioning

confidence: 99%

Section: Wind Tunnelmentioning

confidence: 99%

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Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Richmond-Bryant¹

2003

Numerical Methods in Fluids

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“…A detailed description of this aerosol generation system can be found in Heist et al (2003). The aerosol generation system yielded a spatially uniform concentration profile across the wind tunnel test section with a CV = 6.4%.…”

Section: Experimental Datamentioning

confidence: 99%

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Richmond-Bryant

Eisner

Flynn

2006

Aerosol Science and Technology

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The objective of this work is to evaluate the performance of the steady state Reynolds Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) models for estimating concentration of low Stokes number aerosols (Stk = O(10 −4 )) in the wake of a bluff body. These simulations are compared with experimental data. In the simulations and experiments, particles are released upstream of the body and convected downstream, where some are entrained into the wake. The air velocity is computed using a steady state renormalized group k ∼ ε model. Lagrangian particle trajectory simulations are performed in conjunction with each airflow model to calculate concentrations. The experiments are performed in an aerosol wind tunnel in which phase Doppler velocimetry measurements are obtained the velocity field and for aerosol concentration.The RANS model yields a wake concentration deficit that extends downstream past x/D = 10, while the experiments produce elevated concentrations immediately downstream of the near wake. It is postulated that the concentration peak is at least in part attributed to particle interaction with the boundary layer by the following mechanism. Particles are transported into the boundary layer by turbulent diffusion, turbophoresis, and/or inertial forces. Particles then separate from the cylinder with the airflow and travel in a sheath around the periphery of the near wake to converge at the downstream edge of the near wake. Underestimation of the wake concentration by the RANS model is potentially due to inadequacy in the boundary layer approximation used in the model.

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“…With a stable, uniform concentration in the wind-tunnel, a single point measurement of freestream concentration would be sufficient to determine the upstream aerosol characteristics. Uniform particle concentration in the wind tunnel can be achieved using multiple identical particle injectors spread over the tunnel cross-section (Heist, Richmond-Bryant, Eisner & Conner 2003). Such an injection approach would, however, result in significant blockage of the cross-section, and influence the wind-tunnel flow characteristics.…”

Section: Methodsmentioning

confidence: 98%

Numerical simulations of the sampling performance of a large particle inlet

Zhao

Chen

Holsen

et al. 2015

Journal of Aerosol Science

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a b s t r a c tThe sampling performance characteristics of a funnel-shaped large particle inlet (LPI) were obtained experimentally using wind-tunnel measurements and the results compared against computational fluid dynamics (CFD) predictions. In the wind-tunnel, a moving injector system was used to inject polydisperse particles uniformly over the tunnel cross-section and a pair of Aerodynamic Particle Sizers were used to measure sizeresolved sampling efficiencies of the inlet at 3 m s À 1 . The wind-tunnel results differed from earlier published CFD predictions, necessitating a numerical re-analysis of the inlet performance with a higher order turbulence model and a finer mesh grid appropriate for accurate particle turbulent dispersion modeling. The new simulations revealed non-uniformity in the spatial distribution of particles exiting the inlet. As particle measurements were only made from a sub-set of the inlet flow, the spatial distribution of particles needed to be considered for an accurate comparison with numerical simulations. Accounting for the spatial non-uniformity of particles exiting the inlet resulted in reasonably good comparison of simulations with experimental data. The simulation results suggest that the current LPI design results in an almost wind-speed independent sampling performance for particles smaller than 10 mm and a cut-size of $ 20 mm for wind-speeds as large as 4.5 m s À 1 . The CFD results suggest that a simple redesign will result in effective sampling of larger particles but will increase the wind-speed dependence of the inlet's sampling efficiency. Further wind-tunnel testing is required to validate the predicted sampling efficiencies at larger sizes and higher wind-speeds.

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Development of a Versatile Aerosol Generation System for Use in a Large Wind Tunnel

Cited by 13 publications

References 16 publications

Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Verification testing in computational fluid dynamics: an example using Reynolds‐averaged Navier–Stokes methods for two‐dimensional flow in the near wake of a circular cylinder

Considerations for Modeling Particle Entrainment into the Wake of a Circular Cylinder

Numerical simulations of the sampling performance of a large particle inlet

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