**Progress in Experimental Research of Turbine Aeroacoustics**

Andreas Marn, Christian Faustmann and Thorsten Selic

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62431

#### **Abstract**

Modifications on the intermediate turbine duct in order to reduce noise emissions by changing interaction frequencies and/or modes capable to propagate are presented. Also different turbine exit casings are described that are optimised to reduce interaction noise that is propagating through the engine and is one of the major noise sources during landing (operating point approach). The most promising modifica‐ tions to reduce sound power levels are described. Depending on different modifica‐ tions at specific operating points, the reduction of sound power level is between 5 dB and 10 dB, which is a significant reduction. However, some of these measures show an increase in aerodynamic losses. Therefore, a compromise has to be found between higher losses during a short duration (e.g. landing) and significant noise reduction. The chapter focuses on experimental results obtained in the test facilities of the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technol‐ ogy.

**Keywords:** aeroacoustics, low pressure turbine, high pressure turbine, turbine exit casing, intermediate turbine duct
