Velocity rotational speeds

Rotary atomisation produces the most uniform atomisation of any of the aforementioned techniques, and produces the smallest maximum particle sise. It is almost always used with electrostatics and at lower rotational speeds the electrostatics assist the atomisation. At higher rotational speeds the atomisation is principally mechanical in nature and does not depend on the electrical properties of the coating material. If the viscosity of a coating material is sufficiendy low that it can be deUvered to a rotary atomiser, the material can generally be atomised. The prime mover is usually an ak-driven turbine and, provided that the turbine has the requked power to accelerate the material to the angular velocity, Hquid-dow rates of up to 1000 cm /min can be atomised using an 8-cm diameter beU. 

These simple velocity profiles do not indicate directly any dependence of the flow pattern efficiency upon the rotational speed of the centrifuge. A dependence on speed is to be expected on the basis of the argument that at high speeds the gas in the centrifuge is crowded toward the periphery of the rotor and that the effective distance between the countercurrent streams is thereby reduced. It can be seen from the two-sheU model that, as the position of upflowing stream approaches the periphery, the flow pattern efficiency drops off from its maximum value. 

P. Y. McCormick [Chem. Png. Prog., 58(6), 57 (1962)] compared all available data. The comparisons showed that flight geometry and shell speed should be accounted for in the value of K. He suggested that shell rotational speed and flight number and shape must affect the overall balance however, data for evaluating these variables separately are not available. Also, it is not beheved that the effect of gas velocity... 

The impeller discharge rate can be increased at the same power consumption by increasing impeller diameter and decreasing rotational speed and peripheral velocity so that N D is a constant (Eq. 18-4)]. Flow goes up, velocity head and peripheral velocity go down, but impeller torque Tq goes up. At the same torque, N D is constant, P and Q <=< Dl. Therefore, increasing impeller diameter at... 

Increase solids mixing. Improve powder flowahihty of feed. Increase agitation intensity (e.g., impeller speed, fluidization gas velocity, or rotation speed). 

Increase mixer impeller or drum rotation speed or fliiid-hed gas velocity. 

Decrease load to reduce wear Lower-formulation density. Decrease hed-agitation and compaction forces (e.g., mixer impeller speed, fliiid-hed height, bed weight, fluid-hed excess gas velocity, drum rotation speed). 

From dimensional analysis, the expander blade speed, u, is directly proportional to the wheel diameter, D, of the expander, multiplied by the rotational speed, N, of the expander, both of which are dependent on the volume flow of gas and mechanical stresses. The equivalent velocity energy, C, is dependent on the inlet gas conditions to the expander and can be directly translated into available energy by the following equation ... 

Supposing constant rotational speeds, no slip, and an axial inlet, the velocity triangles are as shown in Figure 6-10. For the radial vane, the absolute tangential fluid velocity at the impeller exit is constant—even if the flow rate is increased or decreased. 

Hicks et al. [8] developed a correlation involving the Pumping number and impeller Reynolds number for several ratios of impeller diameter to tank diameter (D /D ) for pitched-blade turbines. From this coiTclation, Qp can be determined, and thus the bulk fluid velocity from the cross-sectional area of the tank. The procedure for determining the parameters is iterative because the impeller diameter and rotational speed N appear in both dimensionless parameters (i.e., Npe and Nq). 

Even though the rotational velocity changes, the flow is still parallel to the blades, and the hydraulic efficiency remains the same regardless of rotational speed. 

Recently, the regulation of impeller rotational velocity has become a popular regulation mode for volume flow. Electric-motor rotational velocity is regulated by a frequency changer, and its price has dropped lately. Changing the rotational speed also affects the circumference velocity of the impeller. The volume flow can be changed by the same ratio as rotational speed. The form of the velocity triangles and the efficiency remain the same. 

Models for description of liquids should provide us with an understanding of the dynamic behavior of the molecules, and thus of the routes of chemical reactions in the liquids. While it is often relatively easy to describe the molecular structure and dynamics of the gaseous or the solid state, this is not true for the liquid state. Molecules in liquids can perform vibrations, rotations, and translations. A successful model often used for the description of molecular rotational processes in liquids is the rotational diffusion model, in which it is assumed that the molecules rotate by small angular steps about the molecular rotation axes. One quantity to describe the rotational speed of molecules is the reorientational correlation time T, which is a measure for the average time elapsed when a molecule has rotated through an angle of the order of 1 radian, or approximately 60°. It is indirectly proportional to the velocity of rotational motion. 

These types of agitator are used in low-viscosity systems (ji < 50 kg m 1 s-1) with high rotational speed. The typical tip speed velocity for turbine and intermig is in the region of 3 m s 1 a propeller rotates faster. These impellers are classified as remote clearance type, having diameters in the range 25-67% of the tank diameter. 

There are many parameters influencing the size-related performance of a reactor where feed mixing is important concentrations of reactants, feed flow rate, feed pipe velocity, geometry and size of both reactor and stirrer, and stirrer rotational speed. The following remarks should be kept in mind when composing an experimental program for engineering studies ... 

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