# Repeat Problem 9.18, except with Î¸ = 30â—¦. Again, we will use

Repeat Problem 9.18, except with Î¸ = 30â—¦. Again, we will use these results to compare with a quasi-one-dimensional calculation in Problem 10.16. The reason for repeating this calculation is to examine the effect of the much more highly two-dimensional flow generated in this case by a much larger expansion angle.

Data from Problem 9.18:

Consider a two-dimensional duct with a straight horizontal lower wall, and a straight upper wall inclined upward through the angle Î¸ = 3â—¦. The height of the duct entrance is 0.3 m. A uniform horizontal flow at Mach 2 enters the duct and goes through a Prandtl-Mayer expansion wave centered at the top corner of the entrance. The wave propagates to the bottom wall, where the leading edge (the forward Mach line) of the wave intersects the bottom wall at point A located at distance xA from the duct entrance. Imagine a line drawn perpendicular to the lower wall at point A, and intersecting the upper wall at point B. The local height of the duct at point A is the length of this line AB. Calculate the average flow Mach number over AB, assuming that M varies linearly along that portion of AB inside the expansion wave.

Data from Problem 9.16:

Consider a circular cylinder (oriented with its axis perpendicular to the flow) and a symmetric diamond-wedge airfoil with a half-angle of 5â—¦ at zero angle of attack; both bodies are in the same Mach 5 freestream. The thickness of the airfoil and the diameter of the cylinder are the same. The drag coefficient (based on projected frontal area) of the cylinder is 4/3. Calculate the ratio of the cylinder drag to the diamond airfoil drag. What does this say about the aerodynamic performance of a blunt body compared to a sharp-nosed slender body in supersonic flow?

Related Book For

Fundamentals Of Aerodynamics

6th Edition

Authors: John Anderson

ISBN: 9781259129919

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