Turbine Disc Cavity Purge Flow Sealing Effectiveness

The project sponsor asked the team to determine the mechanical changes necessary to improve the efficiency of a turbine engine. Turbines include a stationary disk with airfoils around its circumference, known as a stator with vanes, upstream of a concentric rotating disk, or rotor, also with airfoils around its circumference, and powered by an electric motor. The mainstream flow enters from the primary inlet and the purge flow enters via a cavity between the stator and rotor. The sealing effectiveness of the cavity is measured by two quantities: the pressure difference across the stator vanes to the rotor blades, and the temperature ratio of the mainstream and purge flows. The main independent mechanical variables that affect these two quantities are vane shape and angle, stator design, ratio of blades to vanes, blade shape and angle, and axial and radial gaps from the stator to the rotor. Changes in these variables were made one at a time and the effects measured by pressure taps and thermocouples across the stator. The data acquired was sent to a personal computer and LabView was used to analyze the pressure pulses and temperature distribution for each test run.