A centrifugal pump is being designed to pump liquid refrigerant R-134a atroom temperature and atmospheric pressure. The impeller inlet and outletradii are r1= 100 and r2= 180 mm, respectively (Fig. 14-42). Theimpeller inlet and outlet widths are b1= 50 and b2= 30 mm (into the pageof Fig. 14-42). The pump is to deliver 0.25 m3/s of the liquid at a net headof 14.5 m when the impeller rotates at 1720 rpm. Design the blade shapefor the case in which these operating conditions are the design conditions ofthe pump (V1,t= 0, as sketched in the figure); specifically, calculate anglesb1and b2, and discuss the shape of the blade. Also predict the horsepowerrequired by the pump.
width=
FIGURE 14-42Relative and absolute velocity vectorsand geometry for the centrifugal pumpimpeller design of Example 14-6.