| Autor: |
Emil Göttlich, Mirko Spitalny, Dominik Broszat, Andreas Marn, Stefan Zerobin, Christian Faustmann |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
20th AIAA/CEAS Aeroacoustics Conference. |
| Popis: |
The paper deals with the investigation on the acoustics of two different turning mid turbine frames (TMTF) in the two-stage two-spool test turbine located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility is a continuously operating cold-flow open-circuit plant which is driven by pressurized air. The flow path consists of a transonic turbine stage (HP) followed by a low pressure turbine stage consisting of a TMTF and a counter-rotating low pressure rotor. Compared to the setup within the EU-Project DREAM, the rig was upgraded by fully circumferentially traversable measurement sections at the inlet of the TMTF as well as downstream of the LP turbine. The two TMTF setups have been investigated at engine like flow conditions. The first configuration consists of 16 highly 3D-shaped turning struts. The goal of the second design was to reduce the length of the TMTF by 10% without increasing the losses and providing the same inflow to the LP turbine rotor. This was achieved by applying 3D-contoured endwalls at the hub. Due to the fact that noise becomes more and more an issue, acoustic measurements were carried out downstream of the low pressure turbine at three different operating conditions representative for approach, cutback and sideline. In order to evaluate the noise emission of the turbine, the outflow duct of the facility was instrumented with a new acoustic measurement setup which uses traversable microphone arrays. Therefore, the emitted sound pressure level and the microphones’ spectra are compared for both configurations. The acoustic field was characterized by azimuthal and radial modes determined by traversing the microphone array over 360 degrees. By comparing the two setups in terms of noise generation, the propagating modes due to the HP turbine were found to be at the same level, while an increase of up to 9 dB in amplitude of the modes related to the LP turbine was found in the 10% shorter setup. This is in good accordance with previous studies, where reducing the distance between stator and rotor of a LPT increases the emitted sound. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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