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Sound transmission in turbomachinery flow ducts

Puttkammer, P.P. (2015) Sound transmission in turbomachinery flow ducts.

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Abstract:The first objective of the present study was to carry out a review of literature regarding existing analytical models that describe the propagation of sounds waves through turbomachinery blade rows. From this analysis it is found that analytical models are defined in the 1970's with Kaji Okazaki [1], [2] as pioneers in this field. Two models (Smith [3] and Koch [4]) are used often in literature after the 1970's, both using different mathematical tools to describe the sound waves through blade rows. Also other phenomena, such as mode trapping and acoustic resonance are discussed in literature. These effect should be considered when calculation models for multiple blade rows are defined. The theory of the blade row model of Smith is discussed, from which it is found that the paper of Smith can only be understood correctly with knowledge of the model of Whitehead [5]. A modification of Smith's blade row model is presented, which is supposed to be theoretically valid. The implementation of the original and the modified model of Smith is not complete, there are still flaws in the understanding of the theory, the implementation of the model, or both. However, since Smith presents results in his paper, it is believed that the understanding of the theory and/or the implementation of the model is achievable. It should also be noted, since the implementation of the modified model is lacking, the validity of the theoretical modification of the blade row model of Smith is not checked. When applying the modified model, one should be aware of this fact.
Item Type:Internship Report (Master)
Deutsches Zentrum für Luft -und Raumfahrt (DLR), Germany
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Keywords:Sound Waves, Plane wave, Blade row, Vorticity distribution, Collocation
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