Gas turbine engines are subject to increased performance and improved efficiency, which leads to rising core temperatures with additional cooling needs. Reducing the parasitic leakage in the secondary flow system is important to meet the challenging requirements. New seal designs have to be tested and optimized at engine like conditions, like high pressure of up to 9 bar and surface speed of up to 280 m/s as well as an adjusted flow field. Flexible seal designs are an innovative approach to reduce leakage mass flows significantly. Axial and radial movements during transient operating conditions can be compensated easily, thus allowing a smaller gap width and minimizing rub and heat load.
This paper describes the design and construction of a new rotating test rig facility. To the knowledge of the authors, this is the only test rig with an adjustable gap width and flow field in a high pressure and speed range. The facility is capable of up to 8 bar differential pressure across the seal and up to 4 bar back pressure. The high revolution engine facilitates a surface speed of up to 280 m/s. A traversable casing allows a quick change of the gap width during operation and simulates radial and axial rotor/stator movements in the engine. The seal movement as well as the resulting gap width are measured during operation to fully understand the seal behavior.
An important feature of the new test rig is the continuously adjustable pre-swirl system. It has been designed to cover the different flow conditions in the real engine. Therefore, a RANS parameter study of the pre-swirl chamber has been conducted, which shows the adjustability of different pre-swirl ratios for constant and changing inlet mass flows.