Instrumentation

Velocity measurements:

The mean velocity in the test section is deduced from the dynamic pressure based on static pressure differences between the settling chamber and the nozzle exit via calibration measurements in the test section. Local velocities near the models are measured with Prandtl-tubes and Betz-manometers, fan-wheel anemometers and hot-wire anemometry.

Pressure measurements:

Different tubes, Betz-manometers, and pressure-difference transducers are available. Pressure distributions over 288 locations may be determined via a system of six synchronous-driven Scanivalve-modules, each one including one transducer and 48 pressure-holes.

Turbulence measurements:

For turbulence measurements a three-channel hot-wire-anemometry system is in use.

Force measurements:

Force measurements may be performed in the aerodynamic tunnel and in the boundary layer tunnel with the aid of two external six-component-platform-wind-tunnel balances based on strain-gauge load cells. Both balances were designed and manufactured at the institute and are based on the same general principle. Apart from constructional details, the balances mainly differ in the maximum loads permitted and in the way they rotate the models. The larger balance used in the aerodynamic tunnel may be rotated as a whole on a base frame within a range of -90° to 90°, so that forces and moments are measured (or deduced, respectively) in a model-fixed coordinate system. The other balance is fixed in space and the model may be rotated relative to the measuring system. The balance for the aerodynamic tunnel may be seen in the aforementioned side view of the test section.

Balance 1:3 x 2000 N horizontal, 3 x 10000 N vertical