Radial machines

Radial-Inflow Turbine The radial-inflow turbine, or inward-flow radial turbine, has been in use for many years. Basically a centrifugal compressor with reversed-flow and opposite rotation, the inward-flow radial turbine is used for smaller loads and over a smaller operational range than the axial turbine. Radial-inflow turbines are only now beginning to be used because little was know about them heretofore. Axial turbines have enjoyed tremendous interest due to their low frontal area, making them suited to the aircraft industiy. However, the axial machine is much longer than the radial machine, making it unsuited for certain vehicular and helicopter applications. Radial turbines are used in turbochargers and in some types of expanders. 

Figure 4-13. Sidestream radial machines of four to eight stages with horizontally split casing and one or two pairs of intermediate nozzles, generally for connecting external intercoolers.

Figure 4-14. Radial machines of one to eight stages with horizontally split casing, partcularly suitable for compressing nitrous gases. There are no dead spaces provoking buildup of an ammonium nitrate salt.

For a radial impeller, aU the flow is discharged at the tip of the impeller, and all the solids are subject to the same speed and head. In the case of the propeller or axial turbine, the velocity istribution is proportional to the radius. All solids pass through a higher shear zone in the case of the radial machine. 

In sewage treatment plant processes as well as in chemical and mining processes, gas is sparged in the hquid. The impeller of the mixer is then used to provide dispersion of the gas and circulation of the tank contents. For radial machines, a small radial impeller is installed at the bottom to mix the gas. In the case of hydrofoils, different approaches are used. If the shaft and blades are hollow, gas may be pumped through the shaft and blades. In other apphcations, the impeller is contained within a cylinder that is within the tank. This prevents flooding the impeller with gas. 

Besides state of the art machines for vacuum generation, the authors have been in contact with a supplier of compression equipment to discuss the application of axial and radial compressors. According to the supplier, the use of axial/radial machines is possible, but it would require some significant modifications of the machine. The available suction pressure is limited to approximately 200 mbar. Axial compressors may provide a suction capacity of about 0.5 million m h at this pressure. The isentropic efliciency is approximately 75%, which is significantly higher in comparison to liquid ring pumps or jet pumps. 

CompoundShrinka.g e. In its simplest form (Fig. 8a) compound shrinkage consists of machining the inner radius of an outer component I, (Qp so that it is smaller than the outer radius of an inner component II, The difference between the two is known as the radial interference 5. To assemble the cylinders, outer component I is heated and/or inner component II cooled so that the outer component can be sHpped over the inner as shown in Figure 8b. When the temperature of the assembly returns to ambient, a compressive stress (pressure) is generated across the interface which simultaneously compresses the inner and expands the outer component and, in so doing, displaces radius (r/j by Uj and radius ( jj by U, Unfortunately, it is difficult to carry out this operation without setting up stresses in the axial direction (32). 

Quadronics (L,iquid Dynamics) Extractor (Doyle et al., U.S. Patent 3,114,707, 1963, and others paper at AlChE meeting, St. Louis, February 1968) This is a horizontally rotated device, a variant of the Podbielniak extractor, in which either fixed or adjustable orifices may be inserted as a package radially. These permit control of the mixing intensity as the liquids pass radially through the extractor. Flow capacities, depending on machine size, range from 0.34 to 340 mVh (1.5 to 1500 gal/min). 

De Laval Extractor (Palmqvist and Beskow, U.S. Patent 3,108,953, 1959) This machine contains a number of perforated cylinders revolving about a vertical shaft. The liquids folfow a spiral path about 25 m (82 ft) long, in countercurrent fashion radially, and mix when passing through me perforations. There are no published performance data. 

Generally, the rolling elements ride on an internal race, installed on the shaft, and an external race, installed in the machine housing. The races and the rolling elements are made of hardened alloy steels, because the contact pressure caused by the radial (or thrust) forces can be eiv high. 

The mechanical seal on the radiator water pump of your car has to work under severe conditions. This seal must resist the pressures and temperatures, corresponding to the velocities of the motor, and the variable operating times. This seal is not a precision seal (it has stamped parts rather than machined components) and the pump is a portable pump. The pump doesn t use a direct coupling but a v-belt pulley with radial loading. The seal must resist many vibrations commencing with the v-belt slapping and whipping. 

For small flowrates, the single-casing radial compressor without intercooling is employed for delivery pressures of up to 4-6 bar. Higher pressures of up to 15 bar are attained with intercooled machines of single- and double-casing design. 

The various application fields in Figure 4-12 are served by the machines illustrated in Figure 4-13 ( RZ ) and Figure 4-14 ( R ). R -h R indicates two type-R compressors in series, A -i- R refers to an axial machine followed by a radial compressor, and so forth. 

An effective way of assembling a machine element such as a gear or pulley to a shaft is by shrink fitting. This involves setting up a radial pressure between a shaft with a slightly larger diameter than the inside diameter of the machine element, termed an interference fit. The part is heated to allow assembly and then on cooling the pressure on the inside diameter is established which maintains its ability to transmit torque from the shaft. 

The radial transducers should be placed within three inches of the bearing, and there should be two radial transducers at each bearing. Care should be taken not to place the probe at the nodal points. The two probes should be mounted 90° apart ( 5°) at a 45° ( 5°) angle from each side of the vertical center. Viewed from the drive end of the machine train, the x probe will be on the right side of the vertical, and the i probe will be on the left side of the vertical. Figures 4-10 and 4-11 show protection systems for a turbine and a gear box respectively. 

The heart of these couplings is the flexing disc it is manufactured from vacuum-degassed alloy steel, forged with a radial-grain orientation, and has a contoured profile machined on high-precision equipment. 

Cylindrical roller bearings low speed and heavy load, but only support radial load excellent tractors, machine tools, mid- and small-si2e motors... 

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