Wind velocities

Wind speed and type of wind flow have a pronounced effect on the atmospheric corrosion rate. This is illustrated by the dry deposition velocity that is defined as the ratio of deposition rate of any gaseous compoimd and the concentration of that compoimd in the atmosphere. 

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Gup and Vane Anemometers. A number of flow meter designs use a rotating element kept in motion by the kinetic energy of the flowing stream such that the speed is a measure of fluid velocity. In general, these meters, if used to measure wind velocity, are called anemometers if used for open-channel Hquids, current meters and if used for closed pipes, turbine flow meters. 

For some high growth-rate biomass species, the carbon dioxide concentration in the air among the leaves of the plant often is considerably less than that in the surrounding atmosphere. Photosynthesis may be limited by the carbon dioxide concentrations under these conditions when wind velocities are low and insolation is high. 

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

This procedure offers the possibiUty of remote noncontact velocity measurement, where no probes disturb the flow. It is thus compatible for use with hot or corrosive gases. Commercial laser velocimeters have become weU-developed measurement tools. Examples of laser velocimetry include remote measurement of wind velocity, measurement of vortex air flow near the wing tips of large aircraft, and in vivo measurement of the velocity of blood flow. 

Lagrangian trajectory models can be viewed as foUowing a column of air as it is advected in the air basin at the local wind velocity. Simultaneously, the model describes the vertical diffusion of poUutants, deposition, and emissions into the air parcel as shown in Eigure 4. The underlying equation being solved is a simplification of equation 5 ... 

Water flow, gal/min Spray-nozzle pressure, Ih/im Water flow per nozzle, gal/min Effective area, length X width, fd Effective height, ft Wind velocity, ft/min... 

Figure 12-25 provides a rapid method of determining the pond-area requirements for a given coohng duty. Di and Do are the approaches to equilibrium for the entering and leaving water, °F V Js trie wind velocity, mFh product PQ represents the area of the pond surface, ft /(gal-min) of flowto thepond. The P factor assumes a pond with uniform flow, without turbulence, and with the water warmer than the air. 

Relative humidity, percent = 50 Wind velocity, mi/h = 5 Dry-bulb air temperature, °F = 68 Solar heat gain, Btu/(h-ft ) = 100 Water quantity, gal/min = 10,000... 

The problem with Eq, (26-60) is that the eddy diffusivity changes with position, time, wind velocity, and prevailing atmospheric conditions, to name a few, and must be specified prior to a solution to the equation, This approach, while important theoretically, does not provide a practical framework for the solution of vapor dispersion problems,... 

These inertial effects become less important for particles with diameters less than 5 /rm and for low wind velocities, but for samplers attempting to collect particles above 5 p.m, the inlet design and flow rates become important parameters. In addition, the wind speed has a much greater impact on sampling errors associated with particles more than 5 fim in diameter (4). 

In its simplest form, a model requires two types of data inputs information on the source or sources including pollutant emission rate, and meteorological data such as wind velocity and turbulence. The model then simulates mathematically the pollutant s transport and dispersion, and perhaps its chemical and physical transformations and removal processes. The model output is air pollutant concentration for a particular time period, usually at specific receptor locations. 

Over relatively flat terrain, which of the following measurements would be expecteti ti, represent conditions most closely at a second site 10 km away wind velocity or loMi amount of cloud ... 

In Gaussian plume computations the change in wind velocity with height is a function both of the terrain and of the time of day. We model the air flow as turbulent flow, with turbulence represented by eddy motion. The effect of eddy motion is important in diluting concentrations of pollutants. If a parcel of air is displaced from one level to another, it can carry momentum and thermal energy with it. It also carries whatever has been placed in it from pollution sources. Eddies exist in different sizes in the atmosphere, and these turbulent eddies are most effective in dispersing the plume. 

Wind velocity and direction temperature stability class precipitation. 

Flare radiation level calculations are to be based on the worst case wind velocity, a design wind velocity of 40 Kph and a maximum of 100 Kph. Vendor shall provide radiation plots for each case. 

Minimum purge gas flow rate required to prevent tip degradation when operating at mm down condition, even under maximum wind velocity,... 

The wind velocities are local values at the height of the doorway, so no additional wind sheltering coefficients or height corrections are necessary. A solution is sought for which both situations above can be handled with the same air curtain device by just changing the fan speed and the heating power of the air curtain. 

The wind velocity (i.e., speed and direction) relative to the building... 

FIGURE 7.101 Pressure distribution doe to wind effect o) uniform wind velocity profile (6) non-uniform wind velocity profile. 

The theory for plane jets is similar to descriptions of circular jets (see Section 7.4) and many derived equations describe both two-dimensional (plane) and three-dimensional (round) jets. The principle is to generate such high air velocity that a shield against pressure difference, temperature difference, and wind velocity is sustained. Howeveg it is not possible to have complete separation by an air curtain. The main reason for this, is that the jet entrains air... 

Another suggestion is to use a supply air temperature equal to 25-30 °C. With an entrance depth of 1.1 m and a pressure difference from outside to inside of 15 Pa (which is equal to a wind velocity of 5 m s at a right angle to the door), the values in Table 10.16 are suggested. 

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