
The wave angle, Mach number and temperature after shock.

Answer to Problem 72EP
The wave angle, Mach number and temperature after shock are βweak=37.21° and βstrong=85.05°, 1.713 and 567.125°R respectively.
Explanation of Solution
Given:
Air pressure, air temperature and Mach number are 14 psia, 40°F and 2 respectively. Flow direction angle is 8°.
Concept used:
Relation of wave angle is expressed as follows:
tanθ=2(Ma12 sin2β−1)tanβ(Ma12(k+cos2β)+2)........ (1)
Here, wave angle is β, angle of deflection is θ and Mach number before ramp is Ma1.
Relation of upstream normal Mach number is expressed as follows:
(Ma1)n=Ma1sinβweak........ (2)
Here, wave weak angle is βweak, upstream normal Mach number is (Ma1)n and Mach number before ramp is Ma1.
Relation of downstream normal Mach number is expressed as follows:
(Ma2)n=√(k−1)((Ma1)n)2+22k((Ma1)n)2−k+1........ (3)
Here, upstream normal Mach number is (Ma1)n and downstream normal Mach number is (Ma2)n.
Relation of the downstream Mach number is expressed as follows:
Ma2=(Ma2)n(sinβweak−θ)........ (4)
Here, wave weak angle is βweak, angle of deflection is θ and downstream Mach number is Ma2.
Relation of downstream pressure is expressed as follows:
p2=p1(2k((Ma1)n)2−k+1k+1)........ (5)
Here, downstream pressure is p2, upstream normal Mach number is (Ma1)n and pressure before ramp is p1.
Relation of downstream Temperature is expressed as follows:
T2=T1(p2p1)(2+(k−1)((Ma1)n)2(k+1)((Ma1)n)2)........ (6)
Here, downstream pressure is p2, downstream temperature is T2, Temperature before ramp is T1 upstream normal Mach number is (Ma1)n and pressure before ramp is p1.
Calculation:
Substitute 8° for θ, 2 for Ma1 and 1.4 for k in equation (1).
tan8°=2((2)2 sin2β−1)tanβ((2)2(1.4+cos2β)+2)0.1405(tanβ(4(1.4+cos2β)+2))=(8 sin2β−2)0.787tanβ+0.562tanβcos2β+1.124tanβ=(8 sin2β−2)
Solve the above equation by iteration. We get two value of wave angle as βweak=37.21° and βstrong=85.05°.
Substitute 37.21° for βweak and 2 for Ma1 in equation (2).
(Ma1)n=2sin37.21°(Ma1)n=1.21
Substitute 1.21 for (Ma1)n and 1.4 for k in equation (3).
(Ma2)n=√(1.4−1)(1.21)2+22×1.4(1.21)2−1.4+1(Ma2)n=0.8360
Substitute 0.8360 for (Ma2)n, 37.21° for βweak and 8° for θ in equation (4).
Ma2=0.8360(sin(37.21°−8°))Ma2=1.713
Substitute 14 psia for p1, 1.4 for k and 1.21 for (Ma1)n in equation (5).
p2=14(2×1.4(1.21)2−1.4+11.4+1)p2=21.58 psia
Substitute 14 psia for p1, 21.58 psia for p2, 500 R for T1. 1.4 for k and 1.21 for (Ma1)n in equation (5).
T2=500(21.5814)(2+(1.4−1)(1.21)2(1.4+1)(1.21)2)T2=567.125°R
Thus, the wave angle, Mach number and temperature after shock are βweak=37.21° and βstrong=85.05°, 1.713 and 567.125°R respectively.
Conclusion:
The wave angle, Mach number and temperature after shock are βweak=37.21° and βstrong=85.05°, 1.713 and 567.125°R respectively.
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