Shrouded Probe Performance: Variable Flow Operation and Effect of Free Stream Turbulence

Chandra, Sumit; McFarland, Andrew R.

doi:10.1080/02786829708965418

Cited by 19 publications

(15 citation statements)

References 7 publications

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“…The turbulence intensity was 5.0, 3.5, and 2.7% for wind speed of 0.56, 2.2, and 6.6 m S-Iwithin the central two-thirds area of the test section. The turbulence decreased slightly with increasing wind speed, similar to results obtained by Chandra and McFarland (1997). The level of turbulence was also in the same range of aerosol wind tunnels of small-to-medium size (Hindsand Kuo 1995;Aizenberg etal.…”

Section: --------------------supporting

confidence: 74%

“…Therefore, we recommend a level of turbulence in the wind tunnel test section of below 8% in the longitudinal direction. This level of turbulence was chosen because Chandra and McFarland (1997) showed that below 8% turbulence the sampling efficiency of an isokinetic sampler was not affected. Table 2 lists the currentEPA requirements for wind tunnel performance and recommended changes.…”

Section: Discussionmentioning

confidence: 99%

“…There did, however, appeartobeanincreaseinvariability ofmeasured sampling efficiency associated with turbulence intensity. Similarly, Chandra and McFarland (1997) found that the sampling efficiency (aspiration minus wall losses) for an isokinetic sampler did not change for turbulence intensity between 4 and 8%; however, the sampling effi ciency did decrease when the turbulence was increased to 12%.…”

Section: Introductionmentioning

confidence: 99%

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An Aerosol Wind Tunnel for Evaluation of Massive-Flow Air Samplers and Calibration of Snow White Sampler

Cheng

Irshad

McFarland

et al. 2004

Aerosol Science and Technology

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][Massive-flow air samplers are being deployed around the world to collect aerosol samples for analysis of radioactivity as a result of nuclear tests and nuclear accidents. An aerosol wind tunnel capable of an 1100 rrr' min -I flow rate was built at Lovelace Respiratory Research Institute (LRRI) to test the sampling efficiency of these samplers. This aerosol wind tunnel uses a stationary air blender to enha nce mixing, and therefore it achieves the required uniform distribution of wind speed and aerosol concentration in the test section. The test section of the wind tunnel has a cross section that is 4.3 m x 3.7 m. The aero sol wind tunnel was tested for performance in terms of distribution of wind speed, turbulent inten sity, SF6 tracer gas concentration, and aero sol concentration. Test criteria consistent with U.S. Environmental Protection Agency (EPA) and Amer ican National Standards Institute (ANSI) standards were ad opted as the guideline s for the aerosol wind tunnel. Additional cr iter ia for aero sol wind tunnel were also recommended. Initial test of the aero sol wind tunnel showed that the wind tunnel could be operated in a wind speed range of 2 to 24 km h-I. Within this ran ge, th e distribution of wind speed SF 6 trace gas concentration and aero sol concentration in two-thirds of the central area of the test section showed coefficient of variances (Ca Vs) of less than 10% for the ran ge of wind speeds. Thi s met the stringent guidelines for aerosol wind tunnel performance set by EPA and ANSI sta nda rds.The LRRI wind tunnel was used to evaluate the collection efficiency of the sampling head of massive-volume air samplers, including the Snow White sampler. Th e sa mpler was tested in this aero sol wind tunnel for particles between 2 and 20 JLm.The sampling flow rat es were 500 and 700 nr' h-I for th e tested wind speeds of2.2 and 6.6 m S-I, respectivel y. The results showed that sampling efficiency was influenced by both sampling flow rate and wind speed. The sampling efficiency decreased with an increase in particle size of between 2 and 20 JLm. Th e sa mpling efficiency also decrea sed as the wind speed was increased from 2.2 to 6.6 m S-I.

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Section: --------------------supporting

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Aerosol Wind Tunnel for Evaluation of Massive-Flow Air Samplers and Calibration of Snow White Sampler

Cheng

Irshad

McFarland

et al. 2004

Aerosol Science and Technology

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“…The small differences in measured versus calculated values may be due to the assumption of discrete sample line components in the calculation while the tube used in the experiment is continuous (Figure 9). Describing and analyzing uncertainties in single sample experiments are given by Kline and McClintock (1953) and used in a study by Chandra and McFarland (1997).…”

Section: Upmentioning

confidence: 99%

“…Stober and Flachsbart (1973) evaluated ammonium fluorescein as a laboratory test aerosol. Fluorescein tagged aerosols were used by Chandra and McFarland (1997) in wind tunnels to evaluate inlets In experimental work, fluorescein tagged aerosols are sampled onto filters. The fluorescein is then transferred to a solution and a fluorometer is used to analyze the fluorescence intensity (FI) of the solution.…”

mentioning

confidence: 99%

Use of Fluorescein in Aerosol Studies

Kesavan¹,

Doherty²

2000

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Fluorescein has been used as a tracer in aerosol studies for the detection and quantification of aerosols. This report summarizes a sequence of experiments conducted to confirm our procedure used for the recovery and detection of fluorescein from filters. Our results confirmed the following: (1) The optimum excitation and emission wavelengths for fluorescein are 492 and 516 nm, respectively. (2) For fluorescence intensity (FI) measurements to be accurate, FI of a sample has to be significantly higher than the FI of water filled test tubes. (3) At higher gain settings, changes in the test tube orientation can affect the FI measurement of low fluorescence material. (4) Consistent alignment of the test tube in the fluorometer reduces the variation in FI measurements. (5) Below the self-quenching limit, the fluorometer readings increase linearly with increasing fluorescein concentrations. (6) After the pH of the recovery solution has reached 8, there is no significant effect on FI measurements for further increase in pH. (7) The change in pH does not affect the shape or the position of the peak of the emission spectrum. (8) Our procedure fully recovers fluorescein from glass fiber filters. (9) Fluorescein samples, prepared for fluorometer measurements, were stable over at least a 12 day period.

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References

2013

Airborne Measurements for Environmental Research

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Shrouded Probe Performance: Variable Flow Operation and Effect of Free Stream Turbulence

Cited by 19 publications

References 7 publications

An Aerosol Wind Tunnel for Evaluation of Massive-Flow Air Samplers and Calibration of Snow White Sampler

An Aerosol Wind Tunnel for Evaluation of Massive-Flow Air Samplers and Calibration of Snow White Sampler

Use of Fluorescein in Aerosol Studies

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