Page 99 - Mechanical Engineers' Handbook (Volume 4)

88 Fluid Mechanics

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Table 11 Drag Coefficients for Two-Dimensional Shapes at Re 10 Based on Frontal Projected
Area (Flow Is from Left to Right)

13.1 Pressure Measurements
Static pressures are measured by means of a small hole in a boundary surface connected to
a sensor—a manometer, a mechanical pressure gage, or an electrical transducer. The surface
may be a duct wall or the outer surface of a tube, such as those shown in Fig. 38. In any
case, the surface past which the fluid flows must be smooth, and the tapped holes must be
at right angles to the surface.
Total or stagnation pressures are easily measured accurately with an open-ended tube
facing into the flow, as shown in Fig. 38.

Table 12 Drag Coefficients for Three-Dimensional Shapes
6
4
Re between 10 and 10 (Flow Is from Left to Right)

a
Mounted on a boundary wall.