Frictional, acceleration

The three terms on the right side are known as frictional, accelerational (local accelaration) and gravitational components of the pressure gradient. Or, in other... 

Again, the three components of the total pressure gradient, friction, acceleration and the static head, are clear. 

Regardless of the method chosen to unwind the coil, the performance requirements of the application must be satisfied in terms of payoff speed and acceleration/deceleration time. The uncoiler drive will have to be sized to accommodate the power required to overcome friction, accelerate the inertia of the coil and any other rotating component to line speed prior to exhausting the stored material in the loop, straighten if required, overcome a drag tensioning brake if supplied, and run at the required production speed. The horsepower required is directly proportional to the torque and speed requirements. For a given application, if the payoff speed requirement is doubled, then the horsepower requirement will be doubled as well. Always use the worst case in terms of material thickness and width, coil size, and payoff speed to determine the drive size requirement for any application. 

In machines forces act on component parts in overcoming friction, accelerating or decelerating or in transmitting power or loads. These forces can be tensile, compressive, shear, bending or torsional. 

The mechanical fracture by abrasive solicitation is mainly caused by the higher rigidity of the structural shell, strongly oriented, of filaments this one being weakened by abrasive frictions accelerates the scissions and fracture propagation, which are shifted toward filaments core with an enhanced speed even for lower stresses. 

Case Number Correlations Pressure Drop, kPa Frictional Acceleration Total Regime... 

An alternative approach is to consider ions of charge z e accelerated by the electric field strengtii, E, being subject to a frictional force, Kj, that increases with velocity, v, and is given, for simple spherical ions of... 

We have used a common notation from mechanics in Eq. (5-4) by denoting velocity, the first time derivative of a , x, and acceleration, the second time derivative, x. In a conservative system (one having no frictional loss), potential energy is dependent only on the location and the force on a particle = —f, hence, by differentiating Eq. (5-3),... 

Pressure Drop. The pressure drop across a two-phase suspension is composed of various terms, such as static head, acceleration, and friction losses for both gas and soflds. For most dense fluid-bed appHcations, outside of entrance or exit regimes where the acceleration pressure drop is appreciable, the pressure drop simply results from the static head of soflds. Therefore, the weight of soflds ia the bed divided by the height of soflds gives the apparent density of the fluidized bed, ie... 

Decomposition Hazards. The main causes of unintended decompositions of organic peroxides are heat energy from heating sources and mechanical shock, eg, impact or friction. In addition, certain contaminants, ie, metal salts, amines, acids, and bases, initiate or accelerate organic peroxide decompositions at temperatures at which the peroxide is normally stable. These reactions also Hberate heat, thus further accelerating the decomposition. Commercial products often contain diluents that desensitize neat peroxides to these hazards. Commercial organic peroxide decompositions are low order deflagrations rather than detonations (279). 

Power. The power requited to drive a belt conveyor is derived from the tensile forces requited to propel or restrain the belt at the design speed. These include the tensile forces produced by the frictional resistance of the drive, conveyor components, and material the acceleration of the material and the gravitational forces requited to lift or lower the material. Detailed information and methods of calculation can be found in belt conveyor design handbooks and in Reference 9. 

Note that the total pressure drop consists of 0.5 velocity heads of frictional loss contrihiition, and 1 velocity head of velocity change contrihiition. The frictional contrihiition is a permanent loss of mechanical energy hy viscous dissipation. The acceleration contrihiition is reversible if the fluid were subsequently decelerated in a frictionless diffuser, a 4,000 Pa pressure rise would occur. 

Frictional heat develops rapidly in some units such as a Baubuiy mixer. The first temperature rise may be beneficial in softening the materials and accelerating chemical reactions. High temperatures detrimental to the product may easily be reached, however, and pro-... 

Ideal (Frictionless) Flow in Nozzles The flow path in well-formed nozzles follows smoothly along the nozzle contour without separating from the wall. The effects of small imperfections and small frictional losses are accounted for by correcting the ideal nozzle flow by an empirically determined coefficient of mscharge. The acceleration of a fluid initially at rest to flowing conditions in an ideal nozzle is given by ... 

G = mass flux V = specific volume of stream P = stream pressure f= friction factor D = duct diameter L = flow length g = acceleration due to gravity b = angle of inclination from vertical... 

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