A New Aircraft Inlet for Sampling Interstitial Aerosol: Design Methodology, Modeling, and Wind Tunnel Tests

Moharreri, Arash; Craig, Lucas; Rogers, D. C.; Dhaniyala, Suresh

doi:10.1080/02786826.2013.800186

Cited by 7 publications

(16 citation statements)

References 29 publications

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“…4), CN measurements made by BASE-I and HIMIL were seen to be significantly elevated. The shatter contamination seen in BASE-I data was likely because, for large incoming particles/droplets, a significant fraction of secondary particles generated from impaction may be larger than 2 µm and the CFD simulations of Moharreri et al (2013) suggested that shatter particles in that size range will enter the aerosol sample. Thus, it could be concluded that shatter-free sampling of interstitial aerosol measurements is possible with the BASE-I design but only in the absence of drizzle/precipitation droplets.…”

Section: Cn Measurements In Liquid Cloudsmentioning

confidence: 99%

“…The primary objective for the deployment of BASE-I in PLOWS was to test the inlet performance under actual flight conditions and compare the obtained data with the wind-tunnel and CFD results of Moharreri et al (2013). The major dimensions and assembly components of the aircraft version of BASE-I are shown in Fig.…”

Section: First Iteration: Base-imentioning

confidence: 99%

“…The SMAI was installed ∼ 15 m behind the aircraft nose on the centerline of the fuselage and the HIMIL was mounted ∼ 14 m behind the aircraft nose and ∼ 1.5 m off the centerline to the left side. A picture of the inlets mounted on the C-130 belly was shown in Moharreri et al (2013).…”

Section: First Iteration: Base-imentioning

confidence: 99%

“…The inability to make incloud aerosol measurements from aircraft has stymied efforts to fully understand aerosol-cloud systems. Recently, the design of a new aircraft inlet for aerosol measurements in clouds, called the Blunt-body Aerosol Sampler (BASE), was introduced (Moharreri et al, 2013). The BASE has a blunt body housing with a forward-facing inlet tube located in its aft region, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…2). Moharreri et al (2013) used computational fluid dynamics (CFD) modeling to arrive at the initial design of the BASE. The CFD predictions were validated with windtunnel measurements of flow fields and particle trajectories around the inlet.…”

Section: Introductionmentioning

confidence: 99%

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Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

et al. 2014

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Abstract. There is limited understanding of the role of aerosols in the formation and modification of clouds, partly due to inadequate data on such systems. Aircraft-based aerosol measurements in the presence of cloud particles have proven to be challenging because of the problem of cloud droplet/ice particle shatter and the generation of secondary artifact particles that contaminate aerosol samples. Recently, the design of a new aircraft inlet, called the Blunt-body Aerosol Sampler (BASE), which enables sampling of interstitial aerosol particles, was introduced. Numerical modeling results and laboratory test data suggested that the BASE inlet should sample interstitial particles with minimal shatter particle contamination. Here, the sampling performance of the inlet is established from aircraft-based measurements. Initial aircraft test results obtained during the PLOWS (Profiling of Winter Storms) campaign indicated two problems with the original BASE design: separated flows around the BASE at high altitudes and a significant shatter problem when sampling in drizzle. The test data were used to improve the accuracy of flow and particle trajectory modeling around the inlet, and the results from the improved flow model were used to guide design modifications of the BASE to overcome the problems identified in its initial deployment. The performance of the modified BASE was tested during the ICE-T (Ice in Clouds Experiment -Tropics) campaign, and the inlet was seen to provide near shatter-free measurements in a wide range of cloud conditions. The initial aircraft test results, design modifications, and the performance characteristics of the BASE relative to another interstitial inlet, the submicron aerosol inlet (SMAI), are presented.

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Section: Cn Measurements In Liquid Cloudsmentioning

confidence: 99%

Section: First Iteration: Base-imentioning

confidence: 99%

Section: First Iteration: Base-imentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

et al. 2014

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Aircraft-Based Aerosol Sampling in Clouds: Performance Characterization of Flow-Restriction Aerosol Inlets

Craig

Moharreri

Rogers³

et al. 2014

Journal of Atmospheric and Oceanic Technology

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Interaction of liquid cloud droplets and ice particles with aircraft aerosol inlets can result in the generation of a large number of secondary particles and contaminate aerosol measurements. Recent studies have shown that a sampler designed with a perpendicular subsampling tube located within a flow-through conduit (i.e., a flow-restriction inlet) was best suited for in-cloud sampling. Analysis of field data obtained from different flow-restriction inlets shows that their critical cloud droplet breakup diameters are strongly dependent on design details and operating conditions. Using computational fluid dynamics (CFD) simulations, in-cloud sampling performance of a selected inlet can be predicted reasonably accurately for known operating conditions. To understand the relation between inlet design parameters and its sampling performance, however, CFD calculations are impractical. Here, using a simple, representative one-dimensional velocity profile and a validated empirical droplet breakup criteria, a parametric study is conducted to understand the relationship between different inlet design features and operating conditions on its critical breakup diameters. The results of this study suggest that an optimal inlet for in-cloud aerosol sampling should have a combination of a restriction nozzle at the aft end of the flow-through conduit to minimize wall-impaction shatter artifacts and a blunt leading edge to minimize shatter artifact generation from the aerodynamic breakup of cloud droplets. Inlets for in-cloud aerosol sampling from aircraft will, therefore, differ significantly in design from those used for clear-air aerosol sampling.

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Abundance of fluorescent biological aerosol particles at temperatures conducive to the formation of mixed-phase and cirrus clouds

et al. 2016

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Abstract. Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric boundary layer is not well known. Many types of biological particles fluoresce when exposed to ultraviolet light, and the Wideband Integrated Bioaerosol Sensor takes advantage of this characteristic to perform real-time measurements of fluorescent biological aerosol particles (FBAPs). This instrument was flown on the National Center for Atmospheric Research Gulfstream V aircraft to measure concentrations of fluorescent biological particles from different potential sources and at various altitudes over the US western plains in early autumn. Clear-air number concentrations of FBAPs between 0.8 and 12 µm diameter usually decreased with height and generally were about 10–100 L−1 in the continental boundary layer but always much lower at temperatures colder than 255 K in the free troposphere. At intermediate temperatures where biological ice-nucleating particles may influence mixed-phase cloud formation (255 K  ≤ T ≤  270 K), concentrations of fluorescent particles were the most variable and were occasionally near boundary-layer concentrations. Predicted vertical distributions of ice-nucleating particle concentrations based on FBAP measurements in this temperature regime sometimes reached typical concentrations of primary ice in clouds but were often much lower. If convection was assumed to lift boundary-layer FBAPs without losses to the free troposphere, better agreement between predicted ice-nucleating particle concentrations and typical ice crystal concentrations was achieved. Ice-nucleating particle concentrations were also measured during one flight and showed a decrease with height, and concentrations were consistent with a relationship to FBAPs established previously at the forested surface site below. The vertical distributions of FBAPs measured on five flights were also compared with those for bacteria, fungal spores, and pollen predicted from the EMAC global chemistry–climate model for the same geographic region.

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A New Aircraft Inlet for Sampling Interstitial Aerosol: Design Methodology, Modeling, and Wind Tunnel Tests

Cited by 7 publications

References 29 publications

Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

Aircraft-Based Aerosol Sampling in Clouds: Performance Characterization of Flow-Restriction Aerosol Inlets

Abundance of fluorescent biological aerosol particles at temperatures conducive to the formation of mixed-phase and cirrus clouds

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