Shape vanes

A centrifugal pump consists of a casing in which revolves an impeller, that is a wheel carrying a number of suitably shaped vanes. The centrifugal force sets up a static head in the casing and a certain velocity is imparted to the liquid. With the discharge valve closed only the static head is noticeable and can be... 

Fig. 3.10. A crescent-shaped vane made of Teflon about 5 mm thick.

L-shaped vanes, also caiied hockey sticks... 

Ship-shaped FPSOs must be designed to weather vane i.e. must have the ability to rotate in the direction of wind or current. This requires complex mooring systems and the connections with the well heads must be able to accommodate the movement. The mooring systems can be via a single buoy or, in newer vessels designed for the harsh environments of the North Sea, via an internal or external turret. Figure 10.33 shows a schematic of the Shell-BP Foinaven FPSO. 

Cup anemometers have shaped cups mounted on the spokes of a wheel. The cups, under the action of the fluid forces, spin in a horizontal plane about a vertical shaft mounted in bearings. Vane or propeller types use a multibladed rotor, the axis of which is parallel to the flow direction as the rotating member. Both designs are commonly used for wind speed measurement or similar appHcations such as the velocity in ventilation ducts. Because of inertia, anemometers are most accurate under steady conditions. Velocity fluctuations cause readings that are too high. 

Vanes may be used to improve velocity distribution and reduce frictional loss in bends, when the ratio of bend turning radius to pipe diameter is less than 1.0. For a miter bend with low-velocity flows, simple circular arcs (Fig. 6-37) can be used, and with high-velocity flows, vanes of special airfoil shapes are required. For additional details and references, see Ower and Pankhurst The Mea.surement of Air Flow, Pergamon, New York, 1977, p. 102) Pankhurst and Holder Wind-Tunnel Technique, Pitman, London, 1952, pp. 92-93) Rouse Engineering Hydraulics, Wiley, New York, 1950, pp. 399 01) and Joreensen Fan Engineerinp, 7th ed., Buffalo Forge Co., Buffalo, 1970, pp. Ill, 117, 118). 

U-shaped clevis to which a vaned tailpiece is attac-hed. The wheel rotates because of the difference in drag for the two sides of the cup, and a signal proportional to the revolutions of the wheel is generated. The velocity is determined from the count over a period or time. The current meter is generally usebil in the range of 0.15 to 4.5 m/s (about 0.5 to 15 ft/s) with an accuracy of 2 percent. For additional information see Creager and Justin, Hydroelectric Handbook, 2d ed., Wiley, New York, 1950, pp. 42-46. 

Figure 5-21 includes an outlet velocity vector triangle for the various vane shapes. Figure 5-20 shows a backward curved impeller that includes the inlet and outlet velocity vector triangle. Because most of the compressors used in process applications are either backward curved or radial, only these two types will be covered in detail. 

To calibrate larger sensors/instruments such as vane anemometers, a wind tunnel is required. A calibration wind tunnel consists of an open or closed tunnel, a fan to deliver the air, a nozzle to shape the velocity profile, and a mesh arrangement to uniform and reduce the flow turbulence. It may be necessary to control the air temperature in the tunnel by means of a heating/cooling sys-... 

The performance curve can also be shifted to match the process requirements by variable inlet guide vanes. Located at the compressor inlet, these vanes change the direction of the velocity entering the first-stage impeller. By changing the angle at which these vanes direct the flow at the impeller, the shape of the head capacity curve can be changed. 

The precise shape of the M4 core can be vaned hy partial sjhstilulion of OR wpth halpde, aad ranges from square lo "hurierfly hut apparently never telrahedral " ... 

Choice of vaned or vaneless diffusers, providing optimum curve shape and high efficiencies. 

Impulse turbine design employs a stationary, circular diaphragm onto which a large number of fixed-position, tear-shaped nozzle blades (vanes) are mounted. High-velocity steam moves across the vanes and produces steam jets that are directed into waterwheel-type buckets, mounted onto discs around the turbine rotor. The pressure of the steam in the buckets forces the shaft to rotate. The kinetic energy of the jets is translated into mechanical work as the shaft turns. 

The same exponent was obtained in both works, although in one case a vaned-disk impeller was used, and in the other, arrowhead-shaped blades. Although the nominal residence time can be determined from a knowledge of gas holdup and volumetric gas flow rate, the nominal residence time (Eq. 36) will equal the statistical average residence time (Eq. 34) for certain cases only (L2). 

The impeller (Figure 8.20) consists of a series of curved vanes so shaped that the flow within the pump is as smooth as possible. The greater the number of vanes on the impeller, the greater is the control over the direction of motion of the liquid and hence the smaller are the losses due to turbulence and circulation between the vanes. In the open impeller, the vanes are fixed to a central hub, whereas in the closed type the vanes are held between... 

For higher pressures, rotary compressors of the sliding vane type will give delivery pressures up to 1 MN/m2. In a compressor of this type, as illustrated in Figure 8.35, the compression ratio is achieved by eccentric mounting of the rotor which is slotted to take sliding vanes which sub-divide the crescent-shaped space between the rotor and... 

Figure 3. Two-dimensional simplification of the Feynman ratchet, consisting of one vane (flat sheet in lower reservoir) and one ratchet (triangular shape in upper reservoir), that is free to move as a rigid whole along the horizontal direction x. The boundary conditions are periodic both left and right and up and down in each container.

This pump contains a slotted rotor driven by a rotating driveshaft. Hardened and polished vanes slide in and out of the slots in the rotor as the rotor turns within an elliptical or circle-shaped cam ring. The spaces between the vanes function as chambers to carry the fluid to be pumped. 

Nose Fuze AN-M103A1, shown in Fig 4-1, is cylindrical in shape, ca 2-inches in diameter and 7.23-in long (including the vane assembly). The fuze contains two explosive trains one for delay action, and another for instantaneous action. The "delay action train" consists of a primer, a delay element,... 

Tail Fuze AN-Mk228, shown in Fig 4-12, is bottle-shaped with a 16-blade arming-vane assembly attached to its outer end. 

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