High Speed Tank

The High Speed Tank is a variable density closed loop transonic turbomachinery wind tunnel, part of the High Speed Loop, the principle facility in the Lab at the time of its founding in 1973.

The High Speed Loop was built as a continuous closed loop variable density air supply for turbomachinery research. To this end two large compressors are installed in the basement machine room, with a combined power of 1.5 MW. These compressors can be combined in series or in parallel to drive air through different experiments. The High Speed Tank uses the air supply from the High Speed Loop to perform cascade tests at up to transonic Mach numbers and at engine realistic Reynolds numbers. The High Speed Loop is also used to power the Secondary Air Systems Rig.

View of High Speed Tank, looking along inlet pipe

The main compressors are sufficient to continuously run cascades at speeds up to Mach 1.35, for a throat area of 80 cm2. The loop is fitted with secondary compressors and vacuum pumps which are used to adjust the pressure within it, thereby changing the density and Reynolds number. Typically the inlet stagnation pressure can be adjusted between circa 0.25 bar and 3 bar, giving chord based Reynolds numbers for a sonic cascade of 50 mm chord blades between 170,000 and 1,700,000.

Linear cascade installed within the tank

The High Speed Tank has facilities for performing traverses of the cascade exit flow using a variety of 3-hole, 5-hole, and Neptune pressure probes. A special calibration section is also available to be fitted to the tank to calibrate these probes. In addition the tank has windows for Schlieren imaging, and other optical techniques. The tank has also been used for steady state thermal measurements using IR cameras, and noise measurements.

Neptune pressure probe for the High Speed Tank, used for sensing the static pressure, stagnation pressure and flow angle at exit from a cascade