Question

Question 6 A centrifugal compressor is required to deliver 8 kg/s of air with a stagnation pressure ratio of 4 rotating at 15,000 rpm. The air enters the compressor at 25°C an 1 bar. Assume that the air enters axially with velocity of 145 m/s and the slip factor is 0.89. The compressor isentropic efficiency is 0.89. Calculate: 4 the rise in stagnation temperature а) (6 marks) work input b) (2 marks) c) impeller tip speed (4 marks) d) impeller tip diameter (2 marks) e) (2 marks) power input and area at the impeller eye f) (4 marks) oooOooo page 5

Anyone can help me ans Q-5?

Answer 1

Griven: 05 = 0.89, ne=0.89, N=15000 rpm, m=8ką, V, -145 m), 9) nc = T2-T, sp = 4 0 oh Tas-T, Also, To= Tix (p) & → 5 2 25 1.47 T2 = 65+273) x 4 4 T2 = 442.826k 6.89 = 442.826-298 Tas - 298 Tag = 460.726k b) work input = cp (Tas-To). = per 1.005(460-426-298) = 1308.318 kW 163. 539 kJ/kg Is e actual power = ma 42² = mcp (Tas-TI) => 8x0.89 x 42² = 13083184103 - U2 = +3.555 m/s 428.664 m/s d> U2 = AD, N₂ - D₂ = 428.664x60 e X15000 D2 = 0.54 58 m 4 power input = micp (Tos-Ti) = $x).005X (460-726-298) = 1308.318 kW