Question

Question 2 Soalan 2] (a) Air flowing steadily in a nozzle experiences a normal shock at a Mach number of 2.5. The pressure and temperature of air are 61.64 kPa and 262.15 K, respectively, upstream of the shock The properties of air are k 1.4 and R = 0.287 kJ/kg K, and the properties of helium arek 1.667 and R 2.0769 kJ/kg-K. [Udara mengalir dengan mantap pada muncung yang mengalami kejutan normal di nombor Mach 2.5. Tekanan dan suhu udara adalah 61.64 kPa dan 262.15 K, masing-masing, di hulu kejutan. Sifat-sifat udara adalah k = 1.4 dan R = 0.287 kJ/kg-K, dan sifat-sifat helium adalah k 1.667 dan R = 2.0769 kJ/kgK.] (i) Evaluate the stagnation pressure and velocity downstream of the shock. [Nilaikan tekanan genangan dan halaju hiliran kejutan.] (10 Marks /Markah) (ii) Determine the entropy change of air across the normal shock wave. [Tentukan perubahan entropi udara merentasi gelombang kejutan normal.] (6 Marks/Markah) (b) If the working fluid in the nozzle is changed to helium and experiences a normal shock under the same conditions, determine the velocity downstream of the shock and the entropy change across the normal shock and compare them with what obtain in Question 2(a)(i) and 2(a)(ii) Jika cecair di dalam muncung ditukar kepada helhum dan mengalami kejutan biasa di bawah keadaan yang sama, tentukan halaju hiliran kejutan dan perubahan entropi merentasi kejutan normal dan bandingkan dengan apa yang didapatkan dalam Soalan 2(a)() dan 2(a)(#).] (9 Marks/Markah)

Answer 1

uk umal shock' homal shack Cat dhat pnt exprjores 262 k PI Air l(helin) k=1.66 R2.0 76g for Av veloat efir tashodk - 324 48mls V, 2.5X 0.263x 1600 811.36 mls Stgnehon temp beforeha shock 2 311-341 a62.+ T Scanned with CS CamScanner

shrgnetian Paresre K- ToI 59.68 2621 og2 10 K 'PG. +bleat M 2.5 2.137 2 712 824 8 52G X P 2 S25 54- KPa 2-137T9137X2E2 39.18s k 4Fc1.L m2.R T A13) hit.02s Xetzt.o x (hD 94-3. 388 mls Ans Scanned with CS CamScanner

Cp Rl 39. 1gs S6.21 262. 0bts1 Helium 92.68 MIs 23 1.ms 23611) 262.15 2x 67X168D 963.58K To E164 1963.Sg 262 15 -k19. Pon364-3 7 56 bl98ss.0 2-798 M. T2 C Scanned with CamScanner CS

T2 7 3 3.4 k uass.o ms 7334 .Aus 733. 2 07X Meliyny 2 K. enpop chay ,^i cate of Hcin fEVe tut n he case df Air itis Pisitive cs Scanned with CamScanner