Question

P, Combustion Chamber P2 Nozzle Exit P3 Ambient atmosphere Note: for perfect expansion, if y is known, pressure ratio and e are not independent. Could 22use isentropic compressible flow solver 1How to improve thrust? 20 Decrease γ Increase p,/P3 20 1.40 60 10 em 5 1.3 1.2 10 20 50 100 200 500 1000 2000 5000 10,000 FIGURE 3-6 Thrust coefficient Cp as a function of pressure ratio, nozzle area ratio, and P-P) This figure is for perfect expansion

Answer 1

Given: = 1.3 Solh: 25 km / Parm二0.002549 MPa 13 + X378 x, 20-6 k -i K-I 1 0 = 52-82 V. 2 52.82T, y^ RT, $15 TI 378 TI Pi l0

2 60.23 Т, 2 37-8 TI 0 0025 49 21969.6 12 T. 60 23T 62-82 T, 20.6VT = 0.0554 52.82 2196.61 52 82VT T8745 F A2 1.8745 F 4 2-13 Ao055

(a Frem graph 3-6 for 3923.1o we gety 0 .002549 Cf 1.8 From graph 3.8 for CF 의,8 /PL = 3923-10 ue get, P3 Ab At sea level graph 36, r we geb Ka1.3 At vacuum, P3 is almost negliqible, so when R/a becomes veny large thmust coefficient appreaches the maxi munm This shows tmust increases as rockat leaves tha adhnosphere and ente ys sma e