The test rig is of an open loop design. The ambient air is led into the compressor trough a settling chamber with a throttle that drops the total pressure at the compressor inlet to 74% of the atmospheric pressure. That allows to decrease the needed electric power. The rotors shaft is driven at the design speed of 11,543 rpm (for the present CREATE compressor) by a 2 MW DC-drive coupled with a gearbox. The air passes through the compressor and is discharged in the collector. A throttling valve is used downstream the collector to control the mass flow rate. The anti-surge valve is automatically opened when the compressor is getting in to surge conditions. There are a pressure sensor and a temperature sensor which detect the surge start.
Concerning the global measurements : the inlet total temperature is measured by 10 sensors in the settling chamber. There are also pressure tap to get the pressure in the settling chamber, but the inlet total pressure is obtained with a Kiel probe in front of the compressor. Total pressure and total temperature probe rakes, located at six circumferential and 5 radial positions in the outlet section upstream the discharge collector, give the exit flow conditions. The rotating speed is measured with capacitive sensor. The accuracy is about 1/10000 rpm. The mass flow rate is measured using a Venturi nozzle located just before the exhaust of the test-rig. Taking into account all the sensors installed for this rig, a total of 215 different measurements are used to obtain the steady operating conditions of the compressor (in a time shorter than 2 seconds).
Different specific techniques are used to investigate the flow field within the compressor. Classical traverse measurements are performed with steady state 3-holes pneumatic probes with temperature sensors. 2D-LDA anemometer with its optical head mounted on a KUKA robot is used to determine the axial and circumferential velocity components in the inter-row, as well as and in the rows, regions (cf. figure below). The experimental work planed for year 2008 aims at acquire unsteady pressure signals within the CREATE compressor.