TURBINE STAGE MASS FLOW EVALUATION IN A COMPRESSION TUBE FACILITY

This paper describes a procedure to determine the mass flow of a cooled turbine stage tested in a compression tube facility. In this type of test rig, high-pressure air pushes a lightweight piston inside a closed cylinder. A quasi-isentropic compression is performed. Then, a shutter valve is opened, the flow enters the settling chamber, chokes the downstream throat and fills up the downstream vacuum tank. Thanks to mass flow and energy balances, pressure and temperature history can be predicted in all the elements of the facility and the mass flow can be evaluated in key locations. The model is validated against a large number of test data and is able to determine the mass flow for each single test. Two different turbine configurations are investigated and single test uncertainties of 0.88 % and 1.6 % are achieved, depending on the test condition. NOMENCLATURE