MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

105velocity of the fluid to pressure head. The impeller vanes may be fixedparallel to, or at any angle to, the shaft axis, or they may be adjustablefor changes in applicationconditions.4.2.3 Mixed FlowMixed flow pumps have impellers which impart to the water both axialand radial motion, i.e., the vanes discharge at some angle between 0’ and90* from the axis. Mixed flow impellers are used in two basic pump designs;the helical flow which utilized a volute casing, and the diagonal flow,as used in the bowl construction of vertical well pumps.4.2.4 Regenerative FlowRegenerative pumps are also referred to as vortex, peripheral, sidechannel, and turbine pumps-- the latter name often leading to confusionwith vertical “turbine” pumps (a misnomer itself). Although the basicprinciple is the same, a fine distinction exists between peripheral andside channel pumps. A peripheral pump has a volute casing at the impellertip which decreases in cross sectional area in the direction of flow(i.e., opposite of a volute pump). The side channel pump casing haswider side passages to retard fluid flow. A peripheral impeller reWi.VeSthe water, as its name impG.es, at its periphery and recirculates the waterSeveral times about its short double blade vanes before discharging. Thisrecirculation is produced by the decreasing volute (or side channel) designwhich causes reverberation of the water back toward the suction inlet. Thisreverberation or vortex action allows the impeller to impart additionalenergy to the water. A regenerative pump can develop heads several times.greater than a volute pump with the same size impeller and speed,,thus