A wind tunnel is a duct through which air is either blown or pulled out to simulate air flow over objects. The
model of the object to be tested, called the prototype, is placed in the test section of the wind tunnel and the
pressures, forces and moments experienced by the model at various wind speeds and in different orientation
with reference to the wind are measured using special transducers. The results of wind tunnel measurements
can be utilized to generate the design data for the prototype. Wind tunnels are useful research and educational
tools for students to study problems related to several areas including fluid mechanics and aerodynamics.
Subsonic wind tunnels are employed for teaching and research in aeronautical, mechanical, automobile, civil,
architectural, environmental and marine engineering departments of educational institutions.
1. Measurement of static and total pressures in wind tunnel.
2. Application of Pitot probe for mean velocity measurement.
3. Wind tunnel flow velocity and fan speed measurement.
4. Surface pressure measurements on a symmetric aerofoil.
5. Lift, drag and pitching moment measurements in aerofoil testing. 6. Aerofoil wake survey.
The Sci-tech Subsonic Wind Tunnel Model AT 004 is a suction type open circuit wind tunnel designed to
conduct teaching and basic research experiments related to fluid mechanics and aerodynamics. All tunnel
components are supported on metal frames and include lockable castors for mobility. The wind tunnel
components are of metal construction suitably surface treated or painted to avoid corrosion. The combination
of bell mouth entry, settling chamber with honey comb and three screens and large nozzle contraction ratio
provide tunnel mean flow uniformity and turbulence values required for any basic and applied aerodynamic
research. Air filter is provided to ensure dust free air for the use of hot wire anemometry for flow fluctuation
measurements. The square test section is designed for easy installation and changing of models, accessories
and instrumentation. Transparent glass windows are provided to facilitate optical measurement techniques
such as LDV and flow visualization. Diffuser transition is designed to decelerate the flow without flow
separation from the walls. The drive system consists of a six-bladed fan and a variable speed motor and
controller. Wind tunnel test speeds up to about 60m/s can be obtained. Vibration during tunnel operation is
minimized by suitable mounting of the fan drive system. The floor mounted model support system is provided
to position models in the test section and conduct tests at various angles of incidence. Model having standard
geometrical details such as NACA 0012 symmetric aerofoil sections with surface pressure tapings is provided
for comparison with available data in the literature and ensure proper calibration of testing procedure. Tunnel
operation, control, data acquisition and processing of data are through a computer based system.
• Suction type open circuit wind tunnel.
• Test velocity range: 0-60m/s.
• Total head variation: within +/- 0.5%.
• Mean flow uniformity: within +/- 0.25%.
• Longitudinal turbulence: within 0.15%.
• Test section, 0.3m x 0.3m x 1.5m long, with glass side windows.
• Bell mouth entry, 1.5m X 1.5m.
• Dust filters: Ashrae dust gravimetric efficiency: 97.5%.
• Setting chamber with honey comb (200mm deep and 15mm (mesh).
• Screens, 3 Nos. Bronze,0.14mesh.
• Contraction, contraction ratio 25:1
• Diffuser transition and safety screen (to protect fan).
• Axial flow fan, 6-bladed, 0.6m dia. with housing.
• DC motor fan drive with thyristor controller, 20 kW, 1500 RPM with digital speed indicator and control unit.
• Carriage, mounted on rails fitted with motorized vertical traversing system with a digital position indicator for probes.
• Floor mounted model support and incidence mechanism.
• Control panel with digital display of fan drive and tunnel test parameters.
• PC based data acquisition.
• Symmetric aerofoil model with surface pressure taps.
Probes and Instrumentation:
• Static pressure taps on test section top wall (at 100mm intervals).
• Orifices for probes, with 100mm spacing are located on top of test section.
• Pitot probe (2Nos.) with mountings.
• Pitot static probe (2Nos.) with mountings.
• Multi-tube water manometer, 10 tubes, 500mm long.
• Wake rake for wake survey, 12 probes.
• Three component balance, strain gage type, side wall mounted with amplifiers and digital display. Range: axial force: +/- 50N,normal force: +/- 200N and pitching moment: +/- 15 Nm. (Balance of any other ranges can be supplied on request).
• Balance mounting plate.
• Balance calibration system.
• Connectors and tubing.