Propeller pumps

For double suction pumps, using the HI convention, is taken as the total pump flow, although some pubHcations use half-flow, ie, flow per impeller eye. For multistage pumps, the developed head must be taken per stage for the NS calculation. By definition (eq. 9), high head, low flow pumps have low specific speed low head, high flow pumps, such as turbine and propeller pumps, have high specific speed. 

Axial-Flow (Propeller) Pumps (Fig. 10-44) These pumps are essentiahy very-high-capacity low-head units. Normally they are designed for flows in excess of 450 mVh (2000 gal/min) against heads of 15 m (50 ft) or less. They are used to great advantage in closed-loop circulation systems in which the pump casing becomes merely an elbow in the line. A common installation is for calandria circulation. A charac teristic cui ve of an axial-flow pump is given in Fig. 10-45. 

FIG. 10-44 Axial-flow elbow-type propeller pump. Cowtesy of hawrence Pumps, Inc.)... 

A propeller pump is another type of positive displacement pump. It operates similar to a fan blade inside of a pipe or tube. As fluid moves past the blade, the energy of the moving blade delivers fluid through the outlet at a higher pressure than delivered. 

Some typical applications of the alloys are in propeller shafts, propellers, pump impeller blades, casings, condenser tubes and heat exchanger tubes. The corrosion rate in flowing seawater is <0.025 mm/yr, but can pit under stagnant water. Alloy 400 is immune to chloride SCC. 

Figure 4.4 shows various types of impellers that are used in centrifugal pumps. The one in a is used for axial-flow pump. Axial-flow pumps are pumps that transmit the fluid pumped in the axial direction. They are also called propeller pumps, because the impeller simply propels the fluid forward like the movement of a ship with propellers. The impeller in d has a shroud or cover over it. This kind of design can develop more... 

Propeller pumps—The same as axial-flow pumps. 

Propeller pumps, which pump large quantities of fluid at low pressure differences more efficiently than a centrifugal pump... 

Reasonably, the corrosion form is typical at relatively high velocities between the material surface and flie fluid, and it is particularly intensive in cases of two-phase or multiphase flow, i.e. hquid-gas and liquid-solid particle flow. Components often liable to erosion corrosion are propellers, pumps, turbine parts, valves, heat exchanger tubes, nozzles, bends, and equipment exposed to liquid sputter or jets. Most sensitive materials are those normally protected by corrosion products with inferior strength and adhesion to flie substrate, e.g. lead, copper and its alloys, steel, and under some conditions aluminium/aluminium alloys. Stainless steel, titanium... 

Folsom lectured and contributed widely to the transactions and the scientific societies on the transportation of sand in pipelines, the design of propeller pumps and fans, the axial adjustment of deep-well turbine pumps, the performance characteristics of deep-well turbine pumps, the code for measurement of water discharges, nozzle coefficients for free and submerged discharge measurement structures, manometer errors, laboratory manuals and jet propulsion engineering. He was a member of the American Rocket Society ARS, the American Society of Engineering Education ASEE, the Aeronautical Society, and a Fellow of the American Society of Mechanical Engineers ASME. 

Cavitation studies in polymer solutions have centered on jet cavitation, cavitation inception on rotating disks, propellers, pumps and turbines. Jet cavitation studies,[20] show that the cavitation index can be reduced to a half of the previous value when small quantities of Polyox are present in the flow. The cavitation inception index is defined... 

Crystal slurry is classified (crystal size classification) by the circulation amount of the outer cycle which is controlled by the suction nozzles. Small crystals from the solution are entrained from the crystal bed and recycled to the inner circulation driven by the propeller pump 3, where supersaturation is reduced due to degradation of crystal fines. Different crystal concentrations and sizes in inner and outer suspension cycles are caused by different circulation amounts in each cycle. With known crystallization behavior the cycle may be controlled in a way, that in the inner cycle at a low suspension concentration and a relatively high supersaturation nucleation occurs. Otherwise, in the outer cycle at a longer residence time and smaller supersaturation crystal growth is favored. Crystal sizes 0.8-4 mm No crystal fines below 0.3 mm... 

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