Streamline flow

The screw consists of a feed section, a rapid transition section, and a metering section a rounded forward end prevents stagnation. The breaker plate that converts the rotary motion of the melt into smooth, straight flow should have as many holes as possible both ends of each hole should be countersunk for streamlined flow. 

Extrusion Resins. Extmsion of VDC—VC copolymers is the main fabrication technique for filaments, films, rods, and tubing or pipe, and involves the same concerns for thermal degradation, streamlined flow, and noncatalytic materials of constmction as described for injection-molding resins (84,122). The plastic leaves the extmsion die in a completely amorphous condition and is maintained in this state by quenching in a water bath to about 10°C, thereby inhibiting recrystallization. In this state, the plastic is soft, weak, and pHable. If it is allowed to remain at room temperature, it hardens gradually and recrystallizes partially at a slow rate with a random crystal arrangement. Heat treatment can be used to recrystallize at controlled rates. 

Gilliland and Sherwood [Ind. Eng. Chem., 26, 516 (1934)] found that, for vaporization of pure hqiiids in air streams for streamline flow. 

The relation given above for streamline flow can therefore be expressed as... 

Fig. 13-3. The streamline flow patterns around a sampling inlet in a uniform-flow field.

Turbulence Fluid motion made up of random eddies as opposed to streamline flow. 

Turning vanes Curved vanes added to ductwork elbows in an attempt to ensure streamline flow and, by so doing, reduce turbulent losses. 

Fcr piping with air in streamline flow at absolute pressures in the range between 50 microns and 1 millimeter of mercury, the following is a recommended method. Calculation procedures in pressure regions below atmospheric are very limited and often not generally applicable to broad interpretations. 

Figure 2-44. Friction factor for streamlined flow of air at absolute pressures from 50 microns Hg. to 1mm Hg. By permission, Standards for Steam Jet Ejectors, 3rd. Ed., Heat Exchange Institute, 1956 [54] and Standards for Steam Jet Vacuum Systems, 4th Ed., 1988. Note f on same basis as Figure 2-3 [58].

Particle removal in streamline flow is less efficient than for turbulent flow, and may not be effective if the path of travel is not well baffled. 

A. For viscous streamline flow of organic liquids, water... 

Figures 10-47, 10-48, and 10-49 are useful in solving the equivalent of Equation 10-47 for turbulent as well as streamline flow of gases and vapors inside tubes. To use the charts...

Heated Length Correction Factors, Streamline Flow Tube Size Correction Factors for Streamline Flow ... 

Figure 10-49. Flow inside tubes for gases and vapors. Heat transfer coefficient for streamline flow. (Used by permission Ning Hsing Chen, Chemical Engineering, V. 66, No. 1, 1959. McGraw-Hill, Inc. All rights reserved.)...

Streamline flow shell-side cross-flow modified Donohue ... 

This type of blade is well suited to streamline flow conditions and is used extensively on ventilating, air conditioning, and clean and dirty process gas streams. The backward blade does not catch dirt easily. The outstanding and important characteristic is the nonoverloading horsepower. This is the only commonly used blade style with this feature. It is important in process control and eliminates the need for oversized motors or other drivers. Speed of operation is high, which allows direct or belt connection to the driver. Certain streamlined blade designs provide the same basic characteristics with more efficient and quieter operation. The usual... 

The handling system should be designed to provide streamline flow at all times when steady and predictable pressure conditions are essential. 

Pressure drop under streamline flow conditions is directly proportional to the quantity of oil flowing. The effect of reduced flow rate after take-off points, as compared with full flow rate throughout the full length of the pipeline when there is no take-off, should be taken into account to ensure that variation in pressure is within the specified pump output. Special consideration is necessary with gravity and ring main systems serving several take-off points. 

The following empirical formula for estimating pressure drop under streamline flow conditions may be used ... 

The filtration, or superficial face, velocities used in fabric filters are generally in the range of 1 to 10 feet per minute, depending on the type of fabric, fabric supports, and cleaning methods used. In this range, pressure drops conform to Darcy s law for streamline flow in porous media, which states that the pressure drop is directly proportional to the flow rate. The pressure drop across the... 

The recommended radius not only reduces the brittleness effect but also provides a streamlined flow path for the plastic melt in the mold cavity. The radiused corner of the metal in the mold reduces the possibility of its breakdown and thus eliminates a potential repair need. Too large a radius is also undesirable because it wastes material, may cause sink marks, and may even contribute to stresses from having excessive variations in thickness. 

Heat and mass transfer in a channel with streamline flow has been thoroughly studied by many authors. The rates of heat and mass transfer are very rapid at the entrance of a channel, but decline to a steady value... 

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