Modification of the University of Washington Mark 5 in-stack impactor

Esko Kauppinen, Risto Hillamo

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

A 12-stage, medium-flow rate, in-stack, low pressure impactor was designed and built by utilizing the jet plates of the University of Washington Mark 5 in-stack impactor. Impactor design was based on isentropic flow relationships corrected with experimental discharge coefficients measured for stages having similar geometry. Cut diameters were calculated from Stokes equation using the jet core velocity, √Stk50 = 0.49 and evaluating the slip correction factor and gas viscosity at the upstream stage stagnation gas conditions. Calculated aerodynamic cut diameters of stages 1–12 (stages are numbered starting from the smallest cut diameter) were 0.025, 0.039, 0.067, 0.10, 0.16, 0.27, 0.72, 1.4, 2.4, 4.9, 8.4 and 15.6 μm, when the impactor is operated at the overall outlet to inlet pressure ratio of 0.075 under STP conditions.

Operating pressures of the impactor stages were measured and the compressible flow stages 1–6 were calibrated with singly charged DOP-aerosols. Calculated and measured operating pressures agreed to within −9 and +6%. Experimental aerodynamic cut diameters of stages 1–6 were 0.030, 0.043, 0.078, 0.12, 0.30 and 0.36 μm, respectively, being clearly larger than the calculated values. Collection efficiency curves of stages 1–3 and 6 were sharp, having geometric standard deviations in the range 1.13–1.16. Stages 4 and 5 had poorer size classification properties; the geometric standard deviations of their collection efficiency curves were 1.45 and 1.59, respectively. When Stokes numbers were calculated using jet average (adiabatic) velocities and gas stagnation properties upstream the stage, √Stk50-values of stages 1–4 and 6 were in the range 0.45–0.49. The corresponding value for stage 5 was 0.65. Poor size resolution of stages 4 and 5 and a large √Stk50-value of stage 5 indicate that the steepness of the collection efficiency curve and cut point Stokes number of the compressible flow multijet impactor stages depend on the distance between the jet and the collection plates and the downstream to upstream stage pressure ratio.
Original languageEnglish
Pages (from-to)813-827
JournalJournal of Aerosol Science
Volume20
Issue number7
DOIs
Publication statusPublished - 1989
MoE publication typeA1 Journal article-refereed

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Compressible flow
compressible flow
Aerodynamics
Gases
aerodynamics
Viscosity of gases
gas
Aerosols
Flow rate
stack
impactor
low pressure
viscosity
Geometry
aerosol
geometry
rate

Cite this

Kauppinen, Esko ; Hillamo, Risto. / Modification of the University of Washington Mark 5 in-stack impactor. In: Journal of Aerosol Science. 1989 ; Vol. 20, No. 7. pp. 813-827.
@article{c426300441f04be7ba36b462af771283,
title = "Modification of the University of Washington Mark 5 in-stack impactor",
abstract = "A 12-stage, medium-flow rate, in-stack, low pressure impactor was designed and built by utilizing the jet plates of the University of Washington Mark 5 in-stack impactor. Impactor design was based on isentropic flow relationships corrected with experimental discharge coefficients measured for stages having similar geometry. Cut diameters were calculated from Stokes equation using the jet core velocity, √Stk50 = 0.49 and evaluating the slip correction factor and gas viscosity at the upstream stage stagnation gas conditions. Calculated aerodynamic cut diameters of stages 1–12 (stages are numbered starting from the smallest cut diameter) were 0.025, 0.039, 0.067, 0.10, 0.16, 0.27, 0.72, 1.4, 2.4, 4.9, 8.4 and 15.6 μm, when the impactor is operated at the overall outlet to inlet pressure ratio of 0.075 under STP conditions.Operating pressures of the impactor stages were measured and the compressible flow stages 1–6 were calibrated with singly charged DOP-aerosols. Calculated and measured operating pressures agreed to within −9 and +6{\%}. Experimental aerodynamic cut diameters of stages 1–6 were 0.030, 0.043, 0.078, 0.12, 0.30 and 0.36 μm, respectively, being clearly larger than the calculated values. Collection efficiency curves of stages 1–3 and 6 were sharp, having geometric standard deviations in the range 1.13–1.16. Stages 4 and 5 had poorer size classification properties; the geometric standard deviations of their collection efficiency curves were 1.45 and 1.59, respectively. When Stokes numbers were calculated using jet average (adiabatic) velocities and gas stagnation properties upstream the stage, √Stk50-values of stages 1–4 and 6 were in the range 0.45–0.49. The corresponding value for stage 5 was 0.65. Poor size resolution of stages 4 and 5 and a large √Stk50-value of stage 5 indicate that the steepness of the collection efficiency curve and cut point Stokes number of the compressible flow multijet impactor stages depend on the distance between the jet and the collection plates and the downstream to upstream stage pressure ratio.",
author = "Esko Kauppinen and Risto Hillamo",
year = "1989",
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journal = "Journal of Aerosol Science",
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Modification of the University of Washington Mark 5 in-stack impactor. / Kauppinen, Esko; Hillamo, Risto.

In: Journal of Aerosol Science, Vol. 20, No. 7, 1989, p. 813-827.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Modification of the University of Washington Mark 5 in-stack impactor

AU - Kauppinen, Esko

AU - Hillamo, Risto

PY - 1989

Y1 - 1989

N2 - A 12-stage, medium-flow rate, in-stack, low pressure impactor was designed and built by utilizing the jet plates of the University of Washington Mark 5 in-stack impactor. Impactor design was based on isentropic flow relationships corrected with experimental discharge coefficients measured for stages having similar geometry. Cut diameters were calculated from Stokes equation using the jet core velocity, √Stk50 = 0.49 and evaluating the slip correction factor and gas viscosity at the upstream stage stagnation gas conditions. Calculated aerodynamic cut diameters of stages 1–12 (stages are numbered starting from the smallest cut diameter) were 0.025, 0.039, 0.067, 0.10, 0.16, 0.27, 0.72, 1.4, 2.4, 4.9, 8.4 and 15.6 μm, when the impactor is operated at the overall outlet to inlet pressure ratio of 0.075 under STP conditions.Operating pressures of the impactor stages were measured and the compressible flow stages 1–6 were calibrated with singly charged DOP-aerosols. Calculated and measured operating pressures agreed to within −9 and +6%. Experimental aerodynamic cut diameters of stages 1–6 were 0.030, 0.043, 0.078, 0.12, 0.30 and 0.36 μm, respectively, being clearly larger than the calculated values. Collection efficiency curves of stages 1–3 and 6 were sharp, having geometric standard deviations in the range 1.13–1.16. Stages 4 and 5 had poorer size classification properties; the geometric standard deviations of their collection efficiency curves were 1.45 and 1.59, respectively. When Stokes numbers were calculated using jet average (adiabatic) velocities and gas stagnation properties upstream the stage, √Stk50-values of stages 1–4 and 6 were in the range 0.45–0.49. The corresponding value for stage 5 was 0.65. Poor size resolution of stages 4 and 5 and a large √Stk50-value of stage 5 indicate that the steepness of the collection efficiency curve and cut point Stokes number of the compressible flow multijet impactor stages depend on the distance between the jet and the collection plates and the downstream to upstream stage pressure ratio.

AB - A 12-stage, medium-flow rate, in-stack, low pressure impactor was designed and built by utilizing the jet plates of the University of Washington Mark 5 in-stack impactor. Impactor design was based on isentropic flow relationships corrected with experimental discharge coefficients measured for stages having similar geometry. Cut diameters were calculated from Stokes equation using the jet core velocity, √Stk50 = 0.49 and evaluating the slip correction factor and gas viscosity at the upstream stage stagnation gas conditions. Calculated aerodynamic cut diameters of stages 1–12 (stages are numbered starting from the smallest cut diameter) were 0.025, 0.039, 0.067, 0.10, 0.16, 0.27, 0.72, 1.4, 2.4, 4.9, 8.4 and 15.6 μm, when the impactor is operated at the overall outlet to inlet pressure ratio of 0.075 under STP conditions.Operating pressures of the impactor stages were measured and the compressible flow stages 1–6 were calibrated with singly charged DOP-aerosols. Calculated and measured operating pressures agreed to within −9 and +6%. Experimental aerodynamic cut diameters of stages 1–6 were 0.030, 0.043, 0.078, 0.12, 0.30 and 0.36 μm, respectively, being clearly larger than the calculated values. Collection efficiency curves of stages 1–3 and 6 were sharp, having geometric standard deviations in the range 1.13–1.16. Stages 4 and 5 had poorer size classification properties; the geometric standard deviations of their collection efficiency curves were 1.45 and 1.59, respectively. When Stokes numbers were calculated using jet average (adiabatic) velocities and gas stagnation properties upstream the stage, √Stk50-values of stages 1–4 and 6 were in the range 0.45–0.49. The corresponding value for stage 5 was 0.65. Poor size resolution of stages 4 and 5 and a large √Stk50-value of stage 5 indicate that the steepness of the collection efficiency curve and cut point Stokes number of the compressible flow multijet impactor stages depend on the distance between the jet and the collection plates and the downstream to upstream stage pressure ratio.

U2 - 10.1016/0021-8502(89)90092-X

DO - 10.1016/0021-8502(89)90092-X

M3 - Article

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