A1 Journal article (refereed), original research

Effect of FreeStream Velocity Definition on Boundary Layer Thickness and Losses in Centrifugal Compressors


Publication Details
Authors: Tiainen Jonna, Jaatinen-Värri Ahti, Grönman Aki, Turunen-Saaresti Teemu, Backman Jari
Publisher: American Society of Mechanical Engineers (ASME)
Publication year: 2018
Language: English
Related Journal or Series Information: Journal of Turbomachinery
Volume number: 140
Issue number: 5
ISSN: 0889-504X
eISSN: 1528-8900
JUFO-Level of this publication: 1
Open Access: Not an Open Access publication

Abstract

The estimation of boundary layer losses
requires the accurate specification of the freestream velocity, which is
not straightforward in centrifugal compressor blade passages. This
challenge stems from the jet-wake flow structure, where the freestream
velocity between the blades cannot be clearly specified. In addition,
the relative velocity decreases due to adverse pressure gradient.
Therefore, the common assumption of a single freestream velocity over
the blade surface might not be valid in centrifugal compressors.
Generally in turbomachinery, the losses in the blade cascade boundary
layers are estimated, e.g., with different loss coefficients, but they
often rely on the assumption of a uniform flow field between the blades.
To give guidelines for the estimation of the mentioned losses in highly
distorted centrifugal compressor flow fields, this paper discusses the
difficulties in the calculation of the boundary layer thickness in the
compressor blade passages, compares different freestream velocity
definitions, and demonstrates their effect on estimated boundary layer
losses. Additionally, a hybrid method is proposed to overcome the
challenges of defining a boundary layer in centrifugal compressors.


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Last updated on 2019-13-03 at 12:00