QUESTION 1 Air at a stagnation temperature To1 24 °C enters the impeller of a centrifugal compressor in the axial direction. The rotor, which has Z 19 radial vanes, rotates at N = 15000 rpm. The stagnation pressure ratio between diffuser outlet and impeller inlet is 4.5 and total-to-total efficiency is 81 %. Determine the impeller tip radius. Assume that the slip factor σ = 1-2/Z, where Z is the number of vanes. Take = 1. QUESTION 2 A centrifugal compressor runs at a speed of 15x103 rpm and delivers 32 kg of air per second. Exit radius is 0.33 m, and relative tangential velocity at exit is Wu2 117 m/s. Assume axial inlet and To1-300 K and Po1 1 bar. Calculate the torque exerted on the rotor in Nm.