A centrifugal compressor has an impeller with 21 vanes, which are radial at exit, a vaneless diffuser, and no inlet guide vanes. At inlet, the stagnation pressure is 100 kPa (abs) and the stagnation temperature is 300 K
a. Given that the mass flow rate is 2.3 kg/s, the impeller tip speed is 500 m/s and the mechanical efficiency is 96%, determine the driving power on the shaft. Use Eq. (7.34b) for the slip factor
b. Determine the total and static pressures at diffuser exit when the velocity at that position is 100 m/s. The total-to-total efficiency is 82%
c. The reaction, which may be defined as for an axial-flow compressor by Eq. (5.19), is 0.5, the absolute flow speed at impeller entry is 150 m/s, and the diffuser efficiency is 84%. Determine the total and static pressures, absolute Mach number, and radial component of velocity at the impeller exit
d. Determine the total-to-total efficiency for the impeller.
e. Estimate the inlet - outlet radius ratio for the diffuser assuming the conservation of angular momentum.
f. Find a suitable rotational speed for the impeller given an impeller tip width of 6 mm
