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S4B - Model engine calibration

Vacuum chamber for engine simulator thrust calibration

The typical tests

  • Nozzle thrust tests with altitude simulation.
  • Direct or reverse jet model engine calibration, with simulation of the wind tunnel test conditions.
  • Through Flow Nacelles calibrations.
  • Thrust reversers calibrations and jet angularities.

S4B vacuum tank

  • Cylindrical sealed vessel, diameter 2.5 m, length 15 m.
  • Fed by compressed air:
    • two pressure levels, 9 bar and 64 bar;
    • dry and clean air (12 µm mesh filtering, less than 5 mg of water per kg of dry air) with temperature controlled;
    • air storage: 9,500 m3 at 9 bar and 109 m3 at 270 bar.
  • Vacuum connection:
    • internal absolute pressure level from 15 mbar to atmosphere;
    • connection pipes (diameter up to 1,200 mm) toward vacuum tanks with adaptable volume between 1,000 and 8,000 m3;
    • possible vacuum setting by ejector effect (Bertin ejector or using the tested nozzle itself).

 

The test techniques

  • Mass flow control and temperature control of the two jets.
  • Separate control of the pressure upstream of the fan, of the model engine RPM and of the nozzle exit pressure.
  • Test rigs checking using reference nozzles.
  • Jet thrust vector measurement (module and angularity).

Measurements

  • Steady measurements = 64 analog channels, 16 bits A/D converter, digital lowpass filtering with a bandwidth from 0.01 to 10 Hz. Steady accuracy ±1 mV, resolution 0.3mV.
  • On demand, unsteady measurements = 64 analog channels at 100 kHz per channel. 12 bits A/D converter, digital lowpass filtering with a bandwidth from 0 to 20 kHz (if necessary the number of channels can be increased).
  • Steady pressures = 992 channels (by DTC PSI®, system 8400).

Measurement technics

  • Temperature measurement by thermocouples and PT100 probes
  • Load measurement by ONERA six components balances (decoupling device for air flow crossing through).
  • Sonic throat mass flow meters for the primary and fan jets.

Accuracy:

  • the uncertainties in the 4" test rig with the Ø 100 mm reference nozzle are (from test campaigns between 1987 and 2009),
  • flow coefficient: ± 0,1 % in 86 % of the test cases,
  • Thrust coefficient: ± 0,15 % in 81 % of the test cases.