Analyzing Unsteady Turbomachinery Flow Simulations With Mixing EntropySource: Journal of Turbomachinery:;2024:;volume( 146 ):;issue: 007::page 71004-1DOI: 10.1115/1.4064839Publisher: The American Society of Mechanical Engineers (ASME)
Abstract: The prediction of unsteady aerodynamic loads is a central problem during the design of turbomachinery. Over the last 20 years, harmonic balance methods have been shown to be highly efficient for this task. A CPU-cost optimal setup of a harmonic balance simulation, however, requires knowledge of relevant harmonics. In the case of a single blade row with a periodic disturbance this question amounts to the classical problem of harmonic convergence, a problem which is solely due to the nonlinearity of the unsteady flow physics. In contrast, for multi-stage configurations, the choice of harmonics is further complicated by the fact that the interactions of disturbances with blade rows may give rise to a vast spectrum of harmonics that possibly have important modal content, e.g., Tyler–Sofrin modes. The aim of this paper is to show that the mixing entropy attributed to circumferential modes of a given harmonic can serve as a disturbance metric on the basis of which a criterion could be derived whether a certain harmonic should be included or not. The idea is based on the observation that the entropy due to the temporal and circumferential mixing of the flow at a blade row interface may be decomposed, up to third-order terms, into independent contributions from different frequencies and mode orders. For a given harmonic balance (and steady) flow result, the mixing entropy attributed to modes that are simply mixed out, rather than resolved in the neighboring row, is shown to be a natural indicator of a potential inaccuracy. We present important features of the mixing entropy for unsteady disturbances, in particular a close relationship to sound power for acoustic modes. The problem of mode selection in a 1.5-stage compressor configuration serves as a practical example to illustrate our findings.
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contributor author | Frey, Christian | |
contributor author | Geihe, Benedict | |
contributor author | Junge, Laura | |
date accessioned | 2024-04-24T22:51:00Z | |
date available | 2024-04-24T22:51:00Z | |
date copyright | 3/18/2024 12:00:00 AM | |
date issued | 2024 | |
identifier issn | 0889-504X | |
identifier other | turbo_146_7_071004.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4295983 | |
description abstract | The prediction of unsteady aerodynamic loads is a central problem during the design of turbomachinery. Over the last 20 years, harmonic balance methods have been shown to be highly efficient for this task. A CPU-cost optimal setup of a harmonic balance simulation, however, requires knowledge of relevant harmonics. In the case of a single blade row with a periodic disturbance this question amounts to the classical problem of harmonic convergence, a problem which is solely due to the nonlinearity of the unsteady flow physics. In contrast, for multi-stage configurations, the choice of harmonics is further complicated by the fact that the interactions of disturbances with blade rows may give rise to a vast spectrum of harmonics that possibly have important modal content, e.g., Tyler–Sofrin modes. The aim of this paper is to show that the mixing entropy attributed to circumferential modes of a given harmonic can serve as a disturbance metric on the basis of which a criterion could be derived whether a certain harmonic should be included or not. The idea is based on the observation that the entropy due to the temporal and circumferential mixing of the flow at a blade row interface may be decomposed, up to third-order terms, into independent contributions from different frequencies and mode orders. For a given harmonic balance (and steady) flow result, the mixing entropy attributed to modes that are simply mixed out, rather than resolved in the neighboring row, is shown to be a natural indicator of a potential inaccuracy. We present important features of the mixing entropy for unsteady disturbances, in particular a close relationship to sound power for acoustic modes. The problem of mode selection in a 1.5-stage compressor configuration serves as a practical example to illustrate our findings. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Analyzing Unsteady Turbomachinery Flow Simulations With Mixing Entropy | |
type | Journal Paper | |
journal volume | 146 | |
journal issue | 7 | |
journal title | Journal of Turbomachinery | |
identifier doi | 10.1115/1.4064839 | |
journal fristpage | 71004-1 | |
journal lastpage | 71004-11 | |
page | 11 | |
tree | Journal of Turbomachinery:;2024:;volume( 146 ):;issue: 007 | |
contenttype | Fulltext |