Question

ta Vew Wiadcw Helpr Home Tocls 101 2019.0.Cot QUESTION 9 In a jet engine rotor the high pressure axial compressor rotates at a speed of 15000 rpm. The overall stagnation pressure ratio due to compression is 10.1, it was recorded that the air flows at a rate of 16 kg/s. The stagnation properties at the inlet are 215 kPa and 460K. The poly-tropic efficiency of the compressor is 90%. Assume the mean radius of the compressor is constant and equal to 0 25m Calculate the total to-total isentropic efficiency of the compressor. Estimate the number of stages required if the stage loading to be less than 0.45 QUESTION 10 Atmospheric air enters the intake diffuser of a jet aircraft flying at a Mach number of 0.8 at a copstant altitude where the static pressure and temperature are 25kPa and 220K respectively The entrance area of the intake is 0.5m and the area at entry to the compressor is 08 m There is a loss of 10% of the stagnation pressure of the air as it flows to the compressor Using compressible flow theory and assuming adiabatic fiow in the intake determine the Mach number and velocity of the flow entering the compressor

Answer 1

Solu tin (9 Given Speed o the Yotor, N= 15000 ybm Ovevall stotion pvessure radlo , p = 10 loo mlet tagnation tempera ture. To,- 460K Stagna belystrapic eficieney mass Yate air m Jnle ion pressyre, 2, = 215kk 0-90 Mean Yadius m = 025 m The palytropie be caleulate etiengy as Y-1 Y - or air Y1ų 1.4- 0. 37 n = 1.465 presser Com 04tle+ temperature of h- O.317 460x 9 54.L K - comprenian temperatne ij the Ontlet was isentropie 460 (г0] &&d.12 K

Totat-tutotl ejhiciency is dejined the adio t ideal or isentrobic sork to the actual ^ork input as inot To-To ho-o То, - Top 460 0.865 954.46 460 &6.58 Stagbading for Compre ss degined SSOY Cr (Toas To Ahus - temperature atter Jhere To2s s -the exit and the stase N(Ma) (2x0 25% 15m) dn N y = 392.S m/s 0.5 (-0o SXI»*) (Тoл - Ч60) 392-5)2 0.45 52d.90 k. To2s

Temberatre rise in staje One 52d.98 -160 ATS overall ise Tenpera tre 954.46460 = 494.46 AT Number tases L494.u6 AT ATS So ,at least stajes coill be requiref to keep the st3e loadiny less than