The compressor test bench enables a wide range of compressor analyses: From measuring the full compressor map, determining the pumping limit and detailed flow field measurements to special applications such as active noise control on single-stage fans or counter-rotating propfans.
Multistage Two Shaft Compressor Test Facility is available for experimental research on axial machines. It can be used to test not only single or multi-stage compressors, but also counter-rotating compressors, fans and even combinations of low and high pressure compressors at different speeds.
The drive unit consists of two electric motors acting on two concentric shafts of the compressor test rig via a gearbox combination. The speeds of the two motors can be adjusted independently from 0 to 2000 rpm and the direction of rotation is freely selectable. A simple coupling mechanism on the hollow core shaft system also allows both motors to act on a single shaft train. The power of the motors is 5 MW each at nominal speed, so that up to 10 MW is available in coupled operation. Depending on the gear set combination in the gearboxes, output speeds of up to 20,200 rpm can be achieved.
Multistage Two Shaft Compressor Test Facility at the DLR Institute of Propulsion Technology
Calming chamber of the Multistage Two Shaft Compressor Test Facility
The Multistage Two Shaft Compressor Test Facility is available for experimental testing of axial machines. This test rig allows not only the investigation of a single or multi-stage compressor, but also the operation of counter-rotating compressors and fans or low-pressure/high-pressure compressor combinations at different speeds.
The air is drawn in from the atmosphere via the intake tower and enters the stabilisation chamber after a 90° deflection. If required, an inlet throttle can be installed to reduce the overall pressure, for example to reduce the power consumption of the test compressor. The air enters the test compressor through a nozzle. Numerical flow analysis shows the quality of the flow to the test compressor.
For special investigations, such as acoustic tests and detailed measurements of the interaction of shock-vortex systems, the degree of turbulence must be improved with a suitable rectifier. In addition to the speed control of the drive motors, the exhaust throttle downstream of the test specimen is used to set the operating points. This is an electrically operated cylinder throttle. A newly developed pump protection system is installed in this area. The aim is not to completely prevent the compressor from pumping, as is often the case in tests, but to minimise the number of pump surges per approach to the stability limit. After the throttle, the air is returned to the environment via a silencer. For compressors and fans with a low total pressure ratio and correspondingly high mass flow, an additional fan can be installed downstream of the plenum box to overcome pressure losses in the piping system. The air is then discharged via a further discharge tower with silencer. In this mode of operation, a maximum mass flow of 160 kg/s is possible.
The Institute now has several compressor rigs with excellent instrumentation covering almost the entire range of aircraft engines and stationary gas turbines: Rig250: representative of the transonic front stages, UHBR rig: scaled fan rotor of a high-bypass engine, CRISP rig: counter-rotating fan rig.
