The unique trisonic N-3 blow-down wind tunnel has started operation in 1965. The use of a pressure ejector with partial air recirculation enabled operation in three speed regimes:
• subsonic,
• transonic,
• supersonic (range of obtained Mach numbers Ma = 0.2–2.3).
The tunnel is supplied from two spherical compressed air tanks with the combined volume of 2880 m3 and maximum pressure of 7 atm. The air is compressed by compressors with a total capacity of up to 2000 kW, appropriately purified and dried.
The average operating time of the wind tunnel, is:
• for supersonic Mach velocities about 3 minutes,
• for transonic Mach velocities about 5 minutes,
• for subsonic Mach numbers Ma = 0.3–0.5 up to several minutes.
Measurements are performed in a measuring chamber with the diagonal cross section of 0.6 x 0.6 m, which classifies the tunnel as the largest and fastest facility in Poland.
Parameter
Dimensions of the measuring space – height x width 0.6 m x 0.6 m
Measuring space dimensions – length 1.5 m
Working medium air
Speed of the working medium Ma = 0.2–2.3
Wind tunnel N-3 – scope of services
• pressure and weight tunnel tests of aircraft models, measurement of their aerodynamic characteristics and pressure distribution;
• measurements of aerodynamic loads on elements of aircraft models, such as:
- wings,
- horizontal and vertical stabilizers,
- control surfaces,
- stores, etc.;
• measurements of the hinge moment on the controls;
• buffeting boundary determination and its intensity in a wide range of flow velocities;
• flow visualizations using the following methods:
- imaging anemometry (Particle Image Velocimetry, PIV),
- oil,
- Schlieren (monochrome and color);
• tunnel tests of aerodynamic characteristics of profiles;
• pressure measurements of transients with a system forcing oscillatory movements.
