Fill time velocity

Collisions between the Na atoms and molecules will redistribute the atomic velocities and fill the velocity hole created by radiation pressure. These collisions, however, are relatively infrequent. Therefore, ample time exists for a long laser pulse to push the atoms out of resonance before collisions can rethermalize the vapor. This loss in excitation efficiency can be overcome with... 

Assuming a characteristic viscosity of fj = me aTlA/n, where the characteristic rate of deformation is taken as 7 = u/b, where t f is the fill time and u = i 2/t / the characteristic velocity, we can write the viscosity in dimensionless form as... 

Cylindrical tank [10 ]. A cylindrical tank with a radius of 5.0 m and height of 1.5 m is fed by a valve whose flow rate is 2.0 m /h. If you later add a second valve and it is observed that the linear velocity of the liquid height has increased by 20 %, then (a) What is the tilling time with valve 1 (b) What is the filling time with 2 valves , (c) What is the flow rate of valve 2 . Hint If the second valve increases the linear speed of the liquid level by 20 %, then valve 2 has one-fifth the flow rate of valve 1. 

Results of the analytical VARTM flow model [9] the flow front velocity Uf) and the fill time (t) are functions of the length (D) of the saturated region and the thickness ratio h,/h2) between the distribution medium layer and preform. Source Reprinted from references, with the permission from ASME.)... 

Process data [21] are available for injection molding of 66 nylon (see Fig. 8-28). For the case of a 2000-psi cavity pressure, check the moldability relationship, that is. In fill velocity vs fill time, discussed earlier [Eqs. (8-4) and (8-5) and Fig. 8-17]. 

To obtain the needed data, we proceed in the following manner First, we select a part thickness that gives a fill time directly. Next, we read across to the 2000-psi curve and obtain the t L ratio (thickness of part) to cavity length. The fill velocity can be estimated by dividing cavity length by fill time. 

The fill time corresponding to a 0.04-in.-thick part is 0.9 s. This allows a calculation of fill velocity ... 

Repeating the process gives a table of data (fill velocities and fill times). 

Very fast injection speed (0.2 to 0.3 seconds fill time) needs to be maintained to improve weld line strength and flow. To achieve optimum mechanical performance the injection velocity is usually moderate. The portion, which is difficult to fill, the molder can increase the injection velocity to improve melt flow as Increased injection velocity can be more effective than raising the melt temperature and is less likely to degrade the resin. 

Let us present simple one-dimensional example of a porous medium 30-mm long being filled by constant inflow velocity 0.2 mm/sec. Parameters of the porous medium are = 0.5, = 0.012 (thus the theoretical filling time is 74.1... 

Polymer melt viscosity is very dependent on shear rate [54-57]. Increase the injection velocity, decrease the fill time, and increase the shear rate, which can lower the viscosity of the polymer during fill and thereby allow for better chain entanglement and better packing. 

This theory uses high force/velocity for the external cardiac compressions. As a by-product, this technique uses a shorter compression duration (i.e., as little as 20% instead of the usual 50%), without having the active intention of changing the compression depth. Rates of up to 150 compressions per minute (100 compressions per minute is currently advised, see Table 27.1), have been proposed. When modeling from the cardiac pump theory, as long at the compression allows the mitral valve to close, and allows for sufficient filling time, artificial cardiac output will be determined by left ventricular end-diastolic... 

The space velocity is defined as the standard volume of the reactant stream fed per unit time divided by the volume of reactor space filled with catalyst. 

In biphase systems velocity of the steam is often 10 times the velocity of the liquid. If condensate waves rise and fill a pipe, a seal is formed with the pressure of the steam behind it (Fig. 2). Since the steam cannot flow through the condensate seal, pressure drops on the downstream side. The condensate seal now becomes a piston accelerated downstream by this pressure differential. As it is driven downstream it picks up more liquid, which adds to the existing mass of the slug, and the velocity increases. 

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