Measurement technology and test rigs for wind tunnels

The institute has a number of setups that permit experimental wind tunnel analysis of various model configurations with different motion forms to meet the needs of various issues within the field of aeroelasticity. The experimental simulation facilities in the wind tunnel experiment include:

  • forced motion to measure motion-induced air forces and loads on moving structures,
  • self-excited vibration (flutter) and
  • forced responses.

Given that the main focus of analysis is placed on commercial transport aircraft, all models and setups are designed for the Transonic Wind Tunnel in Göttingen, although they are also used in other wind tunnels, e.g. for analysis and exposure to high Reynolds numbers.

Test rigs for wind tunnels

Pitch Test Rig

The Institute operates a pitch test rig (NVS) to demonstrate forced motion. It consists of a symmetrical arrangement of a two-sided hydraulic drive. A 2-D aerofoil model can be clamped between the sections and excited to perform harmonic pitching oscillation.

Gust Test Rig

The gust test rig enables the generation of a defined disturbance (gust field) that will impact a second model located further downstream. A slender 2-D aerofoil model is used as the actual gust generator surface.

Flutter Test Rig

The flutter test rig is used to induce flutter oscillation in aerofoil models in the two degrees of freedom pitch and yaw. To do this, a 2-D airfoil model is suspended elastically from a pitch spring and torsional spring respectively.

Measurement technology

Piezoelectric Sensors to Measure Force

The piezoelectric sensors operate according to the piezoelectric effect: electric polarisation occurs upon mechanical deformation of crystals with polar axes. Depending on the cross section, in quartz, the piezoelectric effect manifests itself as a longitudinal, transversal or shear effect. Hence, it is possible to build force measurement elements made of properly cut slices of quartz that can be used to measure one or several components or moments, depending on the requirements.

PicColor Deformation Measurement

The motion and deformation state of a wind tunnel model is measured using an optical, marker-based photogrammetry system time-synchronised with the pressure and force measurements. This takes place in real time, so that the data acquired can also be used to monitor structural loads in the wind tunnel.