Overview
The Drag Coefficient Apparatus measures the drag force on various geometric shapes (sphere, cylinder, flat plate, streamlined body) mounted in a wind tunnel or water tunnel at different flow velocities. A force balance or load cell measures the drag force, and the velocity is measured using a Pitot tube or anemometer. Students calculate drag coefficient (CD) from measured drag force, fluid velocity, and frontal area, and plot CD vs. Reynolds number for each shape. The experiment validates the classical CD-Re curves and demonstrates why aerodynamic streamlining reduces drag in automotive, aerospace, and civil engineering design applications.
Specifications
| Tunnel type | open circuit wind tunnel or water channel |
| Velocity range | 2 to 20 m/s (air) or 0.1 to 1 m/s (water) |
| Test models | sphere, cylinder, flat plate, aerofoil |
| Model material | aluminium / acrylic |
| Drag force measurement | strain gauge force balance, 0 to 50 N |
| Velocity measurement | Pitot tube + manometer or hot-wire anemometer |
| Test section | 200 mm x 200 mm (minimum) |
| Power supply | 220V AC, 50 Hz |