Why do we stil need experimental test-rigs in hydraulic sciences? We use extensively computatinal sciences to estiate performances of runners. Although it is accurate, Computatinal Fluid Dynamics (CFD) need to be checked with experimental data especially for cavitatin and transients. For that reason when prototype machines are greater than 5 MW or larger than 3 m of diameter it is mandatory to estiate on reduced scaled model with a great accuracy performances according to IEC 60193.
In 2016 the P5 Supergrid team has upgraded the experimental test rig located in Laboratory Cremhyg in Grenoble. To facilitate handling operatins and increase operatinal effiency, large motorized valves and a supervision system have been installed. TM1 is the largest experimental facility on which all kinds of pump-turbines can be tested. At the lowest level a pumping system of 400 kW injects energy into the loop. Head losses are controlled by a 16 bar head breaker for stabilizatin purposes. Discharge is measured by two flwmeters mounted inline for measurement and check. In order to measure mechanical torque a motor/generator with variable speed is mounted on a swinging frame on the pump-turbine shaft.
To obtain test results with suffient accuracy the model should be as large as possible in order to achieve a minimum Reynolds number. So on the test rig the discharge can reach 1000 l/sec or the pressure go up to 100 meters.
Typically generator output is around 300 kW. All various quantiis used for performances calculatins (head, torque, discharge, rotatinal speed) should be estiated with an uncertainty lower than 0.1 %. The fial uncertainty on effiency calculatin must be between 0.15 and 0.2% according to IEC 60193.
In January 2017 all pipes have been installed and all valves have bee checked. But for the P5 Supergrid team the real work is about to begin as this is a comparatie test of a model already tested by our partner GE-Hydro.
“Renovated platform TM1. The new set of valves and the piping system configuration allows to test either pump or turbine mode. The reduce scaled model of pump-turbine will be inserted in the upper part of the platform”