A Low Speed Compressor Test Rig for Flutter Investigations

Abstract

A test facility for aereolastic investigations has been installed at the chair of Aero Engines at the Technische Universität Berlin. The test rig provides data for tool and code validation and is used for basic aeroelastic experiments. It is a low speed wind tunnel which allows free and controlled flutter testing. The test section contains a linear cascade with eleven compressor blades. Nine of them are elastically suspended. The paper presents a detailed description of the test facility, results to evaluate the overall flow quality and an aeroelastic model to predict the flutter velocity and critical interblade phase angles. Hot-wire anemometry has been applied to examine the inlet flow for several Mach- and Reynolds numbers. The results show small turbulence intensities. The blade surface pressure distribution and the flow field of the blade’s suction and pressure side has been accessed by oil flow visualization.

Numerical Assessment of Virtual Control Surfaces for Load Alleviation on Compressor Blades

“…This is consistent with the capabilities of the aeroelastic experimental rig of TU Berlin [22] and appropriate for the first assessments of the novel actuation system proposed here. Simulations in transonic conditions, closer to the actual flow in aero engine compressors, are scheduled as an outlook of this work.…”

“…The chord length is 0.15 m. The pitch to chord ratio corresponds to 0.75. The cascade resembles the experimental facility for aeroelastic assessments of the Chair of Aero Engines at TU Berlin [22]. This allows for comparisons between numerical and experimental data for the clean configuration.…”

“…Plasma actuators are applied on the three central blades of the cascade, in order to take into account the relative effects of plasma between the blades. Two-dimensional numerical simulations are performed, as the flow has been proved to have negligible three-dimensional effects, at least for the conditions considered here [22]. Additionally, plasma actuators are meant to cover the entire blade span when installed, so that their effects can be assumed as mostly two-dimensional.…”

“…Freestream velocities of 34.36 m/s and 19.17 m/s are imposed as a boundary condition at the inlet, consistently with the experimental tests of Refs. [22,26]. An average static pressure condition of 101,325 Pa is imposed at the outlet.…”

“…The plasma induced flow is conceived to be opposite relative to the freestream direction, with the specific aim to generate the aforementioned separated flow areas. Numerical computations performed on the clean blade configuration are validated with experimental data achieved on the wind tunnel facility of the Chair for Aero Engines at Technische Universität (TU) Berlin and with literature results [22][23][24] . Constant angle of attack configurations for the blade cascade are assessed first.…”