3.2 Special Purpose Wind Tunnels
75
(a) Open return circuit
(b) Closed return circuit
Fig. 3.34 Operating modes of the “Noise and wind” facility of the PPRIME Institute (© PPRIME
Institute)
The constitution of the plenum and large mass flow rate of the compressors makes
it possible to create either two coaxial jets or a single jet. The jet diameter, a function
of the Mach number, can reach 75 mm for Mach 1. A third circuit is used to simulate
a “flight effect” by means of a 600 mm diameter jet at 55 m/s surrounding the central
jet. This circuit is powered by a fan and includes a cooling system with a cooling
capacity of 137 kW. As shown in Fig. 3.34, the facility can operate either in an
open loop when the jets are discharged to the atmosphere, or closed loop through
a system of vanes. The anechoic chamber, which has a volume of 12.6 × 10.6 ×
7.85 m
3 , is lined with pyramidal foams ensuring the acoustic properties necessary
for the studies considered. The wind tunnel is equipped with various measurement
systems for probing the turbulent jet region (see Fig. 3.35a), the aerodynamic near
field (see Fig. 3.35.b) and the acoustic field (see Fig. 3.36). The scientific objective is
the development and validation of a jet noise theory based on hydrodynamic stability,
allowing the development of simplified models for forecasting and control in ‘free’
and ‘installed’ configurations.
Two anechoic wind tunnels have been operated since the early 1980s at the Acoustic Centre of the Laboratory of Fluid Mechanics and Acoustics (LMFA) at École
Centrale de Lyon. They result from the combination of open test section wind tunnels and a large acoustic chamber (see Fig. 3.37). The supersonic anechoic wind
tunnel is fed continuously (air flow of 1 kg/s) by a 350 kW centrifugal compressor
cooled by an air and water heater. At the outlet of the compressor, the air passes
through a dryer, then by a soundproof and regulated heating box (72 kW), and by a
set of particle filters. This facility is used for jet studies from nozzles whose diameter
75
(a) Open return circuit
(b) Closed return circuit
Fig. 3.34 Operating modes of the “Noise and wind” facility of the PPRIME Institute (© PPRIME
Institute)
The constitution of the plenum and large mass flow rate of the compressors makes
it possible to create either two coaxial jets or a single jet. The jet diameter, a function
of the Mach number, can reach 75 mm for Mach 1. A third circuit is used to simulate
a “flight effect” by means of a 600 mm diameter jet at 55 m/s surrounding the central
jet. This circuit is powered by a fan and includes a cooling system with a cooling
capacity of 137 kW. As shown in Fig. 3.34, the facility can operate either in an
open loop when the jets are discharged to the atmosphere, or closed loop through
a system of vanes. The anechoic chamber, which has a volume of 12.6 × 10.6 ×
7.85 m
3 , is lined with pyramidal foams ensuring the acoustic properties necessary
for the studies considered. The wind tunnel is equipped with various measurement
systems for probing the turbulent jet region (see Fig. 3.35a), the aerodynamic near
field (see Fig. 3.35.b) and the acoustic field (see Fig. 3.36). The scientific objective is
the development and validation of a jet noise theory based on hydrodynamic stability,
allowing the development of simplified models for forecasting and control in ‘free’
and ‘installed’ configurations.
Two anechoic wind tunnels have been operated since the early 1980s at the Acoustic Centre of the Laboratory of Fluid Mechanics and Acoustics (LMFA) at École
Centrale de Lyon. They result from the combination of open test section wind tunnels and a large acoustic chamber (see Fig. 3.37). The supersonic anechoic wind
tunnel is fed continuously (air flow of 1 kg/s) by a 350 kW centrifugal compressor
cooled by an air and water heater. At the outlet of the compressor, the air passes
through a dryer, then by a soundproof and regulated heating box (72 kW), and by a
set of particle filters. This facility is used for jet studies from nozzles whose diameter