The air flow is supplied by two axial fans Ø1600 powered
by asynchronous motors 2 x 75 kW with frequency
changers feed they supply the flow air capacity above
100 m 3 /s by max 1000 rpm. It is also possible to use very
low velocities that investigate the flow and diffusion of
toxic or radioactive agents in the scales 1:1000 to 1:1500
under the condition of validity of Froude number.
The tunnel is equipped with two reference sensors –
Prandtl sensors (Pitot static tubes) for assessment of
dynamic air pressure and measuring the overall and
static pressure. Differential pressure sensors are also
available for monitoring of wind pressure distributions on
models.
Pressure sensors transfer pressures to electric quantities
which are compiled and saved in a computer; next they
are processed using the LabView software. Saved data
can be used in the next investigations or they can be
shared with tunnel control systems for governing the air
flow velocity settings in tunnel.
Devices:
Digital ALMEMO device with probe type FVAD 35
TH5K2
Three 16-channels pressure scanner type
Scanivalve DSA3217/16 (measuring range up to
2.5 kPa)
CTA (Constant Temperature Anemometry) - an
anemometer with heated wire is a proper device,
working on the principle of King's cooling law. CTA
is used for measuring velocity in a point and
continuously provides information on the velocity
in time series. Presently the BLWT tunnel is
equipped with Mini CTA Type 54T42, sufficient for
simple experiments.
20 Irwin probes - simple omni directional sensors
for wind-tunnel studies of pedestrian level winds.
Figure 1: Positions of measuring devices
Figures 2 + 3: View on moveable arm and anemometer probe
3/2017