1. Design of fan and drive system in wind tunnel
•The drive system of a wind tunnel is the fan and its housing. It's
also known as the power drive. The drive system is the primary
source of wind in a wind tunnel. It draws air into the tunnel and
expels air out. This reduces turbulence and provides greater
control of air velocity.
•The drive section of a wind tunnel is located at the end of the
tunnel, downstream of the test section. This allows the fan to
pull air into a smooth stream instead of pushing it
2. •The drive system must provide the desired flow rate and
pressure drop requirements while maintaining reasonable
energy efficiency.
•The drive unit of a wind tunnel is made up of a fan and a
compressor. It makes up for energy losses for friction and non
isentropic stagnation in shock waves. To isolate vibration,
suitable dampers are selected and placed under the wind tunnel
system
•In a compressor, pressurized air is supplied from a compressor
(usually from storage tanks) through a controlled valve or
regulator to the tunnel.
•In the fans, centrifugal fans or blowers either push or pull air
through the test section.Fans / blowers can be either shaft or
belt-driven, depending on acceptable costs and desired
performance characteristics
3. •Compressor-driven facilities can provide large pressure ratios for
relatively little cost and are often preferred for high speed facilities
that require high stagnation pressures.
•Since typical compressors cannot supply the continuous mass flow
necessary, these tunnels often limit the duration of an experiment to
a few minutes or less, depending on the initial pressure, storage tank
volume, and mass flow rate.
•Fan-based systems can operate continuously, but the cost scales
dramatically with volume flow rate and power requirements. Fans
tend to work best with low-speed facilities.
7. *The design of a fan and drive system in a wind tunnel is crucial for achieving accurate and reliable
aerodynamic testing.
1. Fan Selection:
• Choose a fan with the appropriate flow rate and pressure characteristics for the desired wind tunnel
specifications.
• Consider the Reynolds number range of the anticipated experiments to ensure the fan can provide the
necessary turbulence and flow conditions.
2. Drive System:
• Select a suitable drive system, commonly electric motors or engines, based on the required power
and speed for the fan.
• Ensure the drive system can maintain a consistent speed to achieve a stable and repeatable airflow.
3. Speed Control:
• Implement a speed control mechanism, such as variable frequency drives (VFDs), to adjust fan
speed as needed for different testing scenarios.
• Use control systems to maintain precise speed control and stability during experiments.
8. 4. Ducting and Inlet Design:
• Design the ducting system to minimize turbulence and pressure losses, ensuring a uniform and
controlled flow at the test section.
Incorporate an inlet section that conditions the incoming air to meet the required flow
characteristics.
• 5. Safety Measures:
Implement safety features such as emergency shutdown systems to quickly stop the fan in case of
any anomalies.
Consider protective measures to prevent accidents, like guards around rotating components.
9. 6. Bearing and Lubrication:
• Choose high-quality bearings capable of handling the load and speed requirements of the fan.
Implement a reliable lubrication system to ensure smooth operation and longevity of the bearings.
7. Noise Control:
• Integrate noise control measures to minimize the impact of fan noise on experiments. Consider
acoustic treatments in the design of the wind tunnel facility.
10. 8. Instrumentation:
• Install sensors and instrumentation to monitor parameters like fan speed, airflow, and
pressure differentials for real-time adjustments and data collection.
9. Maintenance Consideration:
• Design the system with easy access for maintenance and repairs, ensuring minimal downtime.
Establish a regular maintenance schedule to prevent issues and prolong the life of the fan and
drive system.
10. Integration with Test Section:
• Ensure proper integration of the fan and drive system with the wind tunnel's test section,
minimizing flow disturbances and ensuring accurate results.
*In summary, a well-designed fan and drive system is essential for the successful operation of a
wind tunnel, providing controlled and repeatable aerodynamic conditions for accurate testing.
