Central Aerohydrodynamic Institute
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Acoustic chamber AC-2

Basic parameters

Maximum acoustic pressure level 160 dB
Test section volume 211 m³
Test section dimensions 9.6×5.5×4.0 m
Operational frequency range 160...20000 Hz
Stagnation temperature 293 K
Maximum jet velocity for contour:
1st circuit: nozzle diameter 0.80 m M = 0.25
2nd circuit: nozzle diameter 0.10 m M = 2.00
3rd circuit: nozzle diameter 0.08 m M = 4.00
Data acquisition-processing system:
Multi-channel data acquisition-processing system B&K PULSE3560C,D
Number of channels 32
Data processing rate up to 200 kHz per a channel
Measurement accuracy ±0.5 dB

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General description

AC-2 acoustic anechoic chamber is used for measurements of aircraft element models under conditions simulating free sound field. The measurements include far and near sound field of cold sub and supersonic jets, jet turbulence measurements, creation of highlevel sound fields, airframe noise investigations, noise of air-conditioning system. The experimental assessment of active noise suppression concepts and innovative technologies (e.g. plasma actuators for jet noise reduction) is another field of application of AC-2. Anechoic chamber is equipped with advanced multichannel data acquisition-processing system for realtime acoustic measurements.

Additional systems:

  • Optical equipment complex includs: IT 228 shear interferometer, spherical mirror of 500 mm diameter, high-speed digital recording equipment.
  • Multi-channel complex to measure and control of the flow aerodynamic characteristics based on pressure transducers and NI DAQ-board.


The following types of tests are performed in anechoic chamber:

  • mid-scale model measurements of the near and far-field jet noise with co-flow of advanced aircraft engines;
  • airframe noise measurements of mid-scale models (landing gear, high-lift devices etc.);
  • acoustic loading measurements on aircraft and missile.

Technological advantages

The unique 3-contour air supply system permits to investigate jet noise characteristics of bypass engines in the presence of co-flow;

Test section dimensions permit to localize the sound sources of scaled airframe element models for take-off and landing conditions.

Practical application

Experimental investigations in AC-2, directed on creation of environment friendly aircraft, are spent both within the limits of Federal Programs of Russian Federation, and under FP7 international projects of the EC. Acoustic anechoic chamber AC-2 is a part of Test complex “Aeroacoustics” accredited by the aviation register of Inter-State Aviation Committee and by Federal Agency “Rostechregulirovanie”.