| Autor: |
Ulf Tapken, Fritz Kennepohl, W. Neise, K. Heing, Lars Enghardt |
| Rok vydání: |
2001 |
| Předmět: |
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| Zdroj: |
7th AIAA/CEAS Aeroacoustics Conference and Exhibit. |
| DOI: |
10.2514/6.2001-2153 |
| Popis: |
The sound field in the outlet duct of a high speed low-pressure turbine was studied to deepen the understanding of the sound generating mechanisms in a three-stage turbine. Special interest was given to the influence of the exit guide vanes (EGV) downstream of the turbine on the noise generation. Six radial rakes carrying ten Kulite-sensor probes each were mounted downstream of the EGVs in the cylindrical duct section of the turbine exit. The rakes were positioned at different azimuthal angles and staggered axially in pairs to avoid probe wake interference. The rakes were traversed azimuthally over 180 degrees in steps of 1.5 degrees to give a total of 240x30 measurement points. All sensor signals were acquired simultaneously with a sampling frequency of 22 kHz and stored digitally for later analysis in the frequency range 0-8.5 kHz. Measurements were made at operating conditions from 63% to 99% rotor design speed. Special attention was given to the blade passing frequencies (BPF) of the three turbine rotors. The chosen experimental setup permits decomposition of the sound field into azimuthal and radial modes. With this information, the sound power transmitted upstream as well as downstream can be calculated for frequencies up to 6 kHz. The results of the mode analysis provide a detailed view on the sound generation mechanisms and interaction processes between the various blade and vane rows. According to Tyler & Sofrin, the noise sources can be separated in rotor/statorand rotor/stator/EGV-interactions with associated azimuthal modes. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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