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Basics of Fluid Mechanics, 2014a

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12.2. OBLIQUE SHOCK 507<br />

Example 12.4:<br />

A cone shown in Figure (12.11) is exposed to supersonic flow and create an oblique<br />

shock. Is the shock shown in the photo weak or strong shock? Explain. Using the<br />

geometry provided in the photo, predict at which Mach number was the photo taken<br />

based on the assumption that the cone is a wedge.<br />

Solution<br />

The measurement shows that cone angle is 14.43 ◦ and the shock angle is 30.099 ◦ .<br />

With given two angles the solution can be obtained by utilizing equation (12.59) or the<br />

Potto-GDC.<br />

M 1 M ys M yw θ s θ w δ<br />

P 0y<br />

P 0x<br />

3.2318 0.56543 2.4522 71.0143 30.0990 14.4300 0.88737<br />

Because the flow is around the cone it must be a weak shock. Even if the cone was<br />

a wedge, the shock would be weak because the maximum (transition to a strong shock)<br />

occurs at about 60 ◦ . Note that the Mach number is larger than the one predicted by<br />

the wedge.<br />

End Solution<br />

Oblique Shock<br />

3<br />

90<br />

k = 1 4<br />

2.5<br />

80<br />

70<br />

2<br />

60<br />

M y<br />

θ<br />

δ<br />

1.5<br />

50<br />

40<br />

1<br />

30<br />

0.5<br />

20<br />

10<br />

0<br />

0<br />

2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0<br />

M x<br />

Thu Jun 30 15:14:53 2005<br />

Fig. -12.12. Maximum values <strong>of</strong> the properties in an oblique shock.

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