Assessing the size distribution of droplets in a cloud chamber from light extinction data during a transient regime

2014 ◽  
Vol 109 ◽  
pp. 29-36 ◽  
Author(s):  
Sorin Nicolae Vâjâiac ◽  
Valeriu Filip ◽  
Sabina Ștefan ◽  
Andreea Boscornea
Keyword(s):  
Size Distribution ◽  
Transient Regime ◽  
Cloud Chamber ◽  
Light Extinction ◽  
Extinction Data

scholarly journals A Diagnostic Technique for Particle Characterization Using Laser Light Extinction

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Kris Barboza ◽  
Lin Ma ◽  
K. Todd Lowe ◽  
Srinath Ekkad ◽  
Wing Ng
Keyword(s):  
Size Distribution ◽  
Laser Light ◽  
Diagnostic Technique ◽  
Size Distribution Function ◽  
Polystyrene Latex ◽  
Light Extinction ◽  
Particle Size Range ◽  
Initial Development ◽  
Particle Ingestion ◽  
Laser Extinction

Increased operations of aircraft, both commercial and military in hostile desert environments have increased the risk of micro-sized particle ingestion into engines. The probability of increased sand and dust ingestion results in increased life cycle costs in addition to increased potential for performance loss. Thus, the ability to accurately assess the amount of inlet debris would be useful for engine diagnostics and prognostic evaluation. Previous engine monitoring studies were based on the particle measurements performed a posteriori. Thus, there exists a need for in situ quantification of ingested particles. This paper describes the initial development of a line-of-sight optical technique to characterize the ingested particles at concentrations similar to those experienced by aircraft in brownout conditions using laser extinction with the end goal of producing an onboard aircraft diagnostic sensor. By measuring the amount of light that is transmitted due to the effects of scattering and absorption in the presence of particles over a range of concentrations, a relationship between particle diameters and the laser light extinction was obtained. This relationship was then used to obtain information on diameters and number densities of ingested particles. The particle size range of interest was chosen to be between 1 and 10 μm and the size distribution function was assumed to be lognormal. Tests were performed on polystyrene latex spheres of sizes 1.32 μm, 3.9 μm, and 5.1 μm in water dispersions to measure diameters and concentrations. Measurements were performed over multiple wavelengths to obtain information on the size distribution and number density of particles. Results of tests presented in this paper establish the validity of the laser extinction technique to provide real time information of ingested particles and will serve as an impetus to carry out further research using this technique to characterize particles.

Classification Inversion Algorithm of Circular Cylinder Particle Size Distribution Based on the Light Extinction Date

2011 ◽  
Vol 105-107 ◽  
pp. 2113-2116
Author(s):  
Hong Tang ◽  
Wen Bin Zheng
Keyword(s):  
Particle Size ◽  
Circular Cylinder ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle System ◽  
Distribution Functions ◽  
Light Extinction ◽  
Particle Sizing ◽  
Inversion Algorithm ◽  
Cylinder Particle

Particulate flow is commonly encountered in industries as well as in many other chemical and mechanical engineering applications. The accurate measurement of particle size distribution is of the utmost importance since it decides the physical and chemical characteristic of the particles. The light extinction method can be used for in-line monitoring of particle systems thus providing real time measurements of both particle size distribution and particle concentration. In light extinction particle sizing, a classification inversion algorithm is proposed for the circular cylinder particles. The measured circular cylinder particle system is inversed with different particle distribution functions and classified according to the inversion errors in the dependent model. The simulation experiments illustrate that it is feasible to use the inversion errors of object functions to inverse the circular cylinder particle size distribution in the light extinction particle sizing technique. This classing inversion algorithm can avoid the defects that the type of the size distribution must be assumed beforehand for the light extinction method.

Horizontal air showers induced by muons with energy above 1013 eV

1968 ◽  
Vol 46 (10) ◽  
pp. S369-S372 ◽  
Author(s):  
T. Matano ◽  
M. Nagano ◽  
S. Shibata ◽  
K. Suga ◽  
G. Tanahashi ◽  
...  
Keyword(s):  
Size Distribution ◽  
Zenith Angle ◽  
Nuclear Interaction ◽  
High Energy ◽  
Cloud Chamber ◽  
The Other ◽  
Active Particle ◽  
Air Showers ◽  
Experimental Distribution ◽  
Electromagnetic Showers

We have been observing horizontal air showers to study the high-energy interactions of muons. Nine horizontal air showers of size greater than 104 and zenith angle above 70° were observed. Two of these showers showed evidence that they are not pure electromagnetic showers but nucleonic showers. One shower contained a nuclear-active particle which produced a nuclear interaction in the cloud chamber, and the other shower contained a muon which penetrated about 103 g cm−2 of iron absorber. The size distribution of the horizontal showers was compared with the calculated one assuming that the nuclear interaction of high-energy muons was negligible. The discrepancy between the experimental distribution and the calculated one is reduced if the nuclear interaction of high-energy muons is taken into account, which supports our view that the horizontal air showers (at least some fraction of them) are produced by nuclear interactions of high-energy muons.

scholarly journals Real-Time Aerosol Optical Properties, Morphology and Mixing States under Clear, Haze and Fog Episodes in the Summer of Urban Beijing

2017 ◽  
Author(s):  
Rui Li ◽  
Yunjie Hu ◽  
Ling Li ◽  
Hongbo Fu ◽  
Jianmin Chen
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Light Absorption ◽  
Large Fraction ◽  
Light Extinction ◽  
Absorption Enhancement ◽  
Air Pollution Control ◽  
Hygroscopic Growth ◽  
Aerosol Optical Properties ◽  
Mixing States

Abstract. Characteristics of aerosol optical properties, morphologies and their relationship were studied in urban Beijing during the clear, haze and fog episodes, sampled from 24th May to 22nd Jun, 2012. Transmission Electron Microscope (TEM), a Cavity Ring Down Spectrometer (CRDS), a nephelometer and an aethalometer were employed to investigate the corresponding changes of the aerosol properties. Five episodes were categorised according to the meteorological conditions, composition and optical variation. Results show the clear episode (EP-2 and EP-4) featured as the low light extinction with less pollutants, which are mostly externally mixed. Coarse particles were scarcely observed in EP-2 due to the washout of a previous heavy rain. Thus the size distribution in EP-2 was smaller than EP-4, which had some mineral particles introduced from the north. In contrast, industry-induced haze (EP-1) and biomass burning-induced haze (EP-5) were both impacted by the south air mass. Higher AOD (Aerosol Optical Depth) values illustrated heavy loading particle concentrations. Due to the collision, size of most particles was larger with the diameter of 1 μm, resulting in a higher scattering coefficient. However, as the influence of severe crop residue combustion, a large fraction of soot was detected, which sticks to the KCl transformed sulphate or nitrate particles. The light absorption enhancement was contributed by both Black Carbon (BC) acceleration and other light absorbing substances. Comparatively, soot fog period detected in EP-3 was mostly internally mixed with sulphates and nitrates, which revealed themselves after electron exposure. The larger size distribution was likely to be caused by both hygroscopic growth and collision. More internally mixed particles were observed, which favored the light absorption. The comparison of all the episodes provides a deeper insight of how mixing states influence the aerosol extinction properties and also a clue to the air pollution control in the crop burning seasons.

scholarly journals Reallocation in modal aerosol models: impacts on predicting aerosol radiative effects

2014 ◽  
Vol 7 (1) ◽  
pp. 161-174 ◽  
Author(s):  
T. Korhola ◽  
H. Kokkola ◽  
H. Korhonen ◽  
A.-I. Partanen ◽  
A. Laaksonen ◽  
...  
Keyword(s):  
Size Distribution ◽  
Interaction Parameter ◽  
Reference Model ◽  
Cloud Droplet ◽  
Particle Growth ◽  
Number Concentration ◽  
Light Extinction ◽  
Aerosol Size Distribution ◽  
Light Extinction Coefficient ◽  
Aerosol Cloud

Abstract. Atmospheric models often represent the aerosol particle size distribution with a modal approach, in which particles are described with log-normal modes within predetermined size ranges. This approach reallocates particles numerically from one mode to another for example during particle growth, potentially leading to artificial changes in the aerosol size distribution. In this study we analysed how the modal reallocation affects climate-relevant variables: cloud droplet number concentration (CDNC), aerosol–cloud interaction parameter (ACI) and light extinction coefficient (qext). The ACI parameter gives the response of CDNC to a change in total aerosol number concentration. We compared these variables between a modal model (with and without reallocation routines) and a high resolution sectional model, which was considered a reference model. We analysed the relative differences in the chosen variables in four experiments designed to assess the influence of atmospheric aerosol processes. We find that limiting the allowed size ranges of the modes, and subsequent remapping of the distribution, leads almost always to an underestimation of cloud droplet number concentrations (by up to 100%) and an overestimation of light extinction (by up to 20%). On the other hand, the aerosol–cloud interaction parameter can be either over- or underestimated by the reallocating model, depending on the conditions. For example, in the case of atmospheric new particle formation events followed by rapid particle growth, the reallocation can cause on average a 10% overestimation of the ACI parameter. Thus it is shown that the reallocation affects the ability of a model to estimate aerosol climate effects accurately, and this should be taken into account when using and developing aerosol models.

Sign in / Sign up

Export Citation Format

Share Document