Aerodynamic methods

Within the framework of the AsiaFlux program, Saigusa et al. (2005) measured the C02 fluxes since 1993 in the forest ecosystem of Takayama using an aerodynamic method to estimate the vertical gradient of C02 concentration and a vortex divergence method to calculate the coefficient of diffusion over the forest canopy. Also, measurements were made of vortex fluxes of sensible heat, water vapor, and C02. 

This text is concerned primarily with methods used on a large industrial scale. Electrolysis, distillation, and chemical exchange, which are useful primarily for separating deuterium and isotopes of other light elements, will be described in Chap. 13. Diffusion methods, the gas centrifuge, and aerodynamic methods, which are used primarily for uranium but are applicable also to other heavy elements, will be described in Chap. 14. 

Both the electrical and aerodynamic methods are well established and effective in maintaining the monodispersity of drop ensembles, once they are produced. 

The direct comparison of the results from optical methods with those from aerodynamic methods requires knowledge of the density of the particles to convert the aerodynamic diameter into the geometric diameter. Because of the unknown porosity of the silica agglomerates, no valid conversion was known. Experiments using a direct optical method to measure fractions of aerodynamic classified silica agglomerates [1] led to an effective particle density of a silica agglomerate of about 0.075 g/cm. ... 

We use here a multi-layer model to calculate crop photosynthesis (An). Each layer is characterized by 4 main parameters k, gc, the leaf area index (LAIj ) of each layer, and the aerodynamic conductance (ga) between two layers. Crop photosynthesis (An) is the sum of aerodynamic CO2 flux,, above the canopy, and soil CO2 flux, < >n. To test this model we compared 0, to the aerodynamic fluxes measured above the canopy by a simplified aerodynamic method. ... 

Other routes to reachieving filament separation have been described and rely on mechanical or aerodynamic forces to affect separation. Figure 4 illustrates one method which utilizes a rotating deflector plane to force the filaments apart while depositing the opened filaments ia overlapping loops (25). After the splayed filaments fall to the deposition surface or forming screen, a suction from below the disposition surface holds the fiber mass in place. 

An aerodynamic wheel cover which includes a two sided circular cover, having an outer edge and an inner edge, and a central aperture. The wheel cover may be affixed by any number of adhesives deposited on one side of said aerodynamic wheel cover adjacent the wheel cover outer edge. The present invention also discloses a method of affixing the wheel cover of the present invention to wheels, the resulting wheels and vehicles. 

From the standpoint of collector design and performance, the most important size-related property of a dust particfe is its dynamic behavior. Particles larger than 100 [Lm are readily collectible by simple inertial or gravitational methods. For particles under 100 Im, the range of principal difficulty in dust collection, the resistance to motion in a gas is viscous (see Sec. 6, Thud and Particle Mechanics ), and for such particles, the most useful size specification is commonly the Stokes settling diameter, which is the diameter of the spherical particle of the same density that has the same terminal velocity in viscous flow as the particle in question. It is yet more convenient in many circumstances to use the aerodynamic diameter, which is the diameter of the particle of unit density (1 g/cm ) that has the same terminal settling velocity. Use of the aerodynamic diameter permits direct comparisons of the dynamic behavior of particles that are actually of different sizes, shapes, and densities [Raabe, J. Air Pollut. Control As.soc., 26, 856 (1976)]. 

For determination of the aerodynamic diameters of particles, the most commonly apphcable methods for particle-size analysis are those based on inertia aerosol centrifuges, cyclones, and inertial impactors (Lundgren et al.. Aerosol Measurement, University of Florida, Gainesville, 1979 and Liu, Fine Paiiicles—Aerosol Generation, Measurement, Sampling, and Analysis, Academic, New York, 1976). Impactors are the most commonly used. Nevertheless, impactor measurements are subject to numerous errors [Rao and Whitby, Am. Ind. Hyg. A.s.soc.]., 38, 174 (1977) Marple and WiUeke, "Inertial Impactors, in Lundgren et al.. Aerosol Measurement and Fuchs, "Aerosol Impactors, in Shaw, Fundamentals of Aerosol Sci-... 

Shahpar S., A Comparative Study of Optimization Methods for Aerodynamic Design of Turbomachinery Blades, 2000-GT-523. 

The particles most likely to cause adverse health effects are the fine particulates, in particular, particles smaller than 10 p and 2.5 mm in aerodynamic diameter, respectively. They are sampled using (a) a high-volume sampler with a size-selective inlet using a quartz filter or (b) a dichotomous sampler that operates at a slower flow rate, separating on a Teflon filter particles smaller than 2.5 mm and sizes between 2.5 mm and 10 mm. No generally accepted conversion method exists between TSP and PM,o, which may constitute between 40% and 70% of TSP. In 1987, the USEPA switched its air quality standards from TSP to PMk,. PM,q standards have also been adopted in, for example, Brazil, Japan, and the Philippines. In light of the emerging evidence on the health impacts of fine particulates, the USEPA has proposed that U.S. ambient standards for airborne particulates be defined in terms of fine particulate matter. 

Black smoke (BS) is a particulate measure that typically contains at least 50% respirable particulates smaller than 4.5 mm in aerodynamic diameter, sampled by the British smokeshade (BS) method. The reflectance of light is measured by the darkness of the stain caused by particulates on a white filter paper. The result of BS sampling depends on the density of the stain and the optical properties of the particulates. Because the method is based on reflectance from elemental carbon, its use is recommended in areas where coal smoke from domestic fires is the dominant component of ambient particulates. 

Test bench methods for machines not too large for test cabins have been developed in order to obtain comparative results. In the case of particles, the tracer gas describes well the behavior of aerodynamic diameter particles less than 5 to 10 gm. For larger particles, correction factors should be used to modify the efficiency results obtained using the tracer gas technique. 

Size-selective sampling Industtial hygiene sampling methods that collect particles with a specific range of aerodynamic diameters. 

Advanced two- and three-dimensional computer analysis methods are used today in the analyses of all critical components to verify aerodynamic, heat transfer, and mechanical performance. Additionally, the reduction of leakage paths in the compressor, as well as in the gas turbine expander, results in further plant efficiency improvements. At the compressor inlet, an advanced inlet flow design improves efficiency by reducing pressure loss. Rotor air cooler heat utilization and adt anccd blade and vane cooling arc also used. 

Inertial impaction is the method of choice for evaluating particle or droplet size delivery from pharmaceutical aerosol systems. This method lends itself readily to theoretical analysis, ft has been evaluated in general terms [39] and for specific impactors [40]. Inertial impaction employs Stokes law to determine aerodynamic diameter of particles being evaluated. This has the advantage of incorporating shape and density effects into a single term. 

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