Suite of wind tunnels

The CSIR’s suite of wind tunnels provides an engineering test, measurement and evaluation foundation to the aerodynamic design efforts of the South African aeronautical industry. The CSIR wind tunnels include a closed circuit sub-sonic tunnel, a transonic tunnel, a trisonic tunnel and a large test section open-circuit low-speed tunnel.

The low-speed wind tunnel (LSWT) is a continuous, single-return wind tunnel with a closed test section. Strut-mounted models are suspended from an overhead six component virtual-centre balance. An auxiliary pitch sector allows sting-supported models to be mounted on a variety of internal strain gauge balances. Test types and capabilities in the LSWT include:

  • Scaled aircraft loads and static stability
  • Pressure distribution
  • Air data probe calibrations
  • Flutter tests
  • Two-dimensional oscillating aerofoil
  • Flow visualisations
  • Helicopter intake characterisations
  • Propeller tests and evaluations

The seven-meter wind tunnel (7mWT) is a continuous, open-circuit tunnel powered by 28 axial flow fans of 30 kW each. Uniform flow distribution across the speed range of the tunnel is given by running the fans in one of 13 different symmetrical patterns.

The test types and capabilities in the 7mWT include:

  • Force measurement (internal balance, platform balance and rotor balance)
  • Pressure measurements
  • Flow visualisations
  • Flow field measurements
  • Unmanned Aerial Vehicle (UAV) and propeller test rigs

The medium-speed wind tunnel (MSWT) is one of the best-equipped and most sophisticated tunnels of its kind in the southern hemisphere. A 20 MW electric motor drives a three-stage axial compressor with variable guide vanes and stator blade angles for accurate Mach number control. This variable-density transonic tunnel operates continuously for optimum productivity and accuracy. The square test section is slotted, with a porosity of 5% for the best possible flow at transonic Mach numbers.

The test types and capabilities in the MSWT include:

  • Captive trajectory (store separation) tests
  • High angle of attack tests
  • Force and pressure measurement
  • Flow visualisations
  • Flutter testing
  • Aerodynamic damping tests

The high-speed wind tunnel (HSWT) is a trisonic, blowdown wind tunnel equipped with a colour Schlieren system for flow visualisation. Subsonic and supersonic Mach numbers are tested using the standard wind tunnel setup, while tests in the transonic regime employ an extra cart that is fitted with a plenum evacuation system and porous walls.

Typical test types and capabilities in the HSWT include:

  • Force measurements
  • Pressure measurements
  • Inlet flow measurements
  • Flow visualisations

Numerous airframes have been tested in the CSIR’s wind tunnels, including subsonic types, such as gyrocopters, helicopters and UAVs, transonic type airframes, such as bombs or combat aircraft, and supersonic airframes of high-speed missiles and projectiles flying at more than four times the speed of sound.

Data collected at the facilities are used for airframe characterisation and to populate complex modelling and simulation environments for broader mission simulation predictions, doctrine development and training.

Contact Person

Mauro Morelli

Technical Specifications

Low-speed wind tunnel

• Speed range: 5 m/s to 120 m/s • Test section: 2.1 m x 1.5 m rectangular with corner fillets. • Atmospheric tunnel • Reynolds number: 6 x 106/m

Seven-metre wind tunnel

• Speed: 2 to 32 m/s in discreet steps • Test section: 7.5 m x 6.5 m x 13 m • Continuous and open circuit

Medium-speed wind tunnel

• Mach no. range: M 0.2 to M 1.4 • Test section: 1.5 m x 1.5 m, 4.5 m length • Reynolds number: 31 x 106/m (M 0.8) • Closed circuit, variable pressure and continuous wind tunnel • Stagnation pressure: 20 to 250 kPa

High-speed wind tunnel

• Mach no. range: M0.6 to M4.3 • Test section: 0.45 m x 0.45 m • Run time: 10 to 40 seconds • Reynolds number: 6 to 50 x 106/m • Stagnation pressure range: 70 to 950 kPa

Key Concept

Wind tunnels
Wind tunnels are essentially large tubes with air moving inside them. They are used to simulate the actions of the airflow over an airframe in a controlled test environment.