CUED Publications database

Filtering mixing planes for low reduced frequency analysis of turbomachines

Pullan, G and Adamczyk, JJ (2016) Filtering mixing planes for low reduced frequency analysis of turbomachines. In: UNSPECIFIED.

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Abstract

Copyright © 2016 by ASME A class of problems in turbomachinery is characterised by unsteady interactions at low reduced frequencies. These interactions are often the result of perturbations with length-scale on the order of the machine circumference and examples include axial compressors operating with inlet distortion, fans with downstreampylons, and turbine rotors downstreamof mid-frame struts. Typically, this unsteadiness is accompanied by higher frequency fluctuations caused by perturbations with a length-scale on the order of a blade pitch. Conventional numerical analysis of this class of problem requires computations with a time step governed by the high frequency content but a greatly reduced run time could be achieved if the time step were dictated solely by the low reduced frequency, long length-scale, interaction of interest. In this paper, a filtering mixing plane technique is proposed that removes unwanted short length-scale perturbations at the interfaces between blade rows. This approach gives the user control over the amount ofmixing that occurs at these interfaceswith the limits being fully mixed-out to pitchwise uniformity (conventional mixing plane) or no mixing (conventional sliding plane). By choosing to retain only enough harmonics to resolve the low reduced frequency interaction of interest, an order of magnitude reduction in run time can be achieved.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Subjects: UNSPECIFIED
Divisions: Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:39
Last Modified: 12 Oct 2017 01:51
DOI: