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Isentropic Compression Tube Cascade Facility CT-2C

The short duration, isentropic compression tube cascade facility CT-2 provides full similarity with modern aero engine operating conditions with respect to Mach and Reynolds numbers as well as freestream / wall / coolant temperature ratios. It consists of a 5 m long, 1 m diameter cylinder containing a light-weight piston.

Isentropic Compression Tube Cascade Facility CT-2The new CT-2C configuration. From left to right:
plenum and sonic throat, test section (in red) with traversing system installed, compression tube
CT-2 tube and test section, around 1990

The cylinder is isolated from the test section by a fast-opening shutter valve. As the piston is pushed forward by the action of high pressure air, the gas in front of it is isentropically compressed until it reaches the desired pressure and temperature levels. The shutter valve is then actuated, allowing the heated, high-pressure air to flow over the model, typically a two-dimensional linear cascade.  Steady free-stream flow conditions are maintained for 100 to 800 ms, and these conditions can be varied between 300 and 550 K and 0.5 and 7 bar. A 37 m3 dump tank and a second sonic throat allow downstream pressure adjustments between 0.1 and 4 bar.  Secondary air for film cooling applications can be produced at temperatures as low as 200 K. The maximum test section dimensions for this facility are 250 mm x 100 mm. Upstream periodic wakes can also be generated if needed.

Pressure, temperature, turbulence, convective heat transfer and aerodynamic measurements are performed using fast response transducers and/or transient techniques, and then recorded with a high-speed data acquisition system.  The data are then visualized and processed. Complementary information is obtained from schlieren visualizations.

Isentropic Compression Tube Cascade Facility CT-2

Simplified cutview of the CT-2 original configuration