Abstract

The unsteady characteristics of the velocity field around the tongue of the volute in a centrifugal fan with forward-curved blades were investigated by time-resolved particle image velocimetry and mode decomposition analysis, i.e., proper orthogonal decomposition (POD) and spectral proper orthogonal decomposition (SPOD). Both POD and SPOD analysis reveal the existence of two types of unsteadiness in the flow field in the volute, one is the large-scale fluctuations at rotation frequency and its high-order harmonics in the main outlet flow, the other is due to the jet–wake structures at blade passing frequency in the cutoff clearance region. Additionally, SPOD analysis reveals a third type of disturbance, which is characterized as strip-like velocity structures at the intermediate frequency. The geometric and dynamic features of these coherent flow structures are inspected by the eigenfunction and their reduced-order reconstruction. In comparison with the POD analysis, the SPOD analysis enables the examination of the spatial pattern of each frequency component due to its dual-orthogonality nature. These structures direct impact the tongue, and thus might be responsible for the generation of strong wall-pressure fluctuation on the nose of the tongue. Due to the frequency mixing limitation of POD analysis, they cannot be easily identified from the leading-order POD modes. Furthermore, the frequency range of these three groups of disturbances, as well as their spatial extension, are determined via SPOD analysis and reduced-order reconstruction.

References

1.
Najjari
,
M. R.
,
Montazerin
,
N.
, and
Akbari
,
G.
,
2015
, “
On the Presence of Spectral Shortcut in the Energy Budget of an Asymmetric Jet–Wake Flow in a Forward-Curved Centrifugal Turbomachine as Deduced From SPIV Measurements
,”
J. Turbul.
,
16
(
6
), pp.
503
524
.10.1080/14685248.2015.1013629
2.
Johnson
,
M. W.
, and
Moore
,
J.
,
1980
, “
The Development of Wake Flow in a Centrifugal Impeller
,”
ASME J. Eng. Power
,
102
(
2
), pp.
382
389
.10.1115/1.3230265
3.
Cau
,
G.
,
Mandas
,
N.
,
Manfrida
,
G.
, and
Nurzia
,
F.
,
1987
, “
Measurements of Primary and Secondary Flows in an Industrial Forward-Curved Centrifugal Fan
,”
ASME J. Fluids Eng.
,
109
(
4
), pp.
353
358
.10.1115/1.3242671
4.
Akbari
,
G.
,
Montazerin
,
N.
, and
Akbarizadeh
,
M.
,
2012
, “
Stereoscopic Particle Image Velocimetry of the Flow Field in the Rotor Exit Region of a Forward-Blade Centrifugal Turbomachine
,”
Proc. Inst. Mech. Eng., Part A
,
226
(
2
), pp.
163
181
.10.1177/0957650911430285
5.
Velarde-Suárez
,
S.
,
Ballesteros-Tajadura
,
R.
,
Santolaria-Morros
,
C.
, and
González-Pérez
,
J.
,
2001
, “
Unsteady Flow Pattern Characteristics Downstream of a Forward-Curved Blades Centrifugal Fan
,”
ASME J. Fluids Eng.
,
123
(
2
), pp.
265
270
.10.1115/1.1351175
6.
Velarde-Suárez
,
S.
,
Ballesteros-Tajadura
,
R.
,
Hurtado-Cruz
,
J. P.
, and
Santolaria-Morros
,
C.
,
2004
, “
Numerical Calculation of Wall Pressure Fluctuations in a Centrifugal Fan
,”
ASME
Paper No. HT-FED2004-56848. 10.1115/HT-FED2004-56848
7.
Ballesteros-Tajadura
,
R.
,
Velarde-Suárez
,
S.
,
Hurtado-Cruz
,
J. P.
, and
Santolaria-Morros
,
C.
,
2006
, “
Numerical Calculation of Pressure Fluctuations in the Volute of a Centrifugal Fan
,”
ASME J. Fluids Eng.
,
128
(
2
), pp.
359
369
.10.1115/1.2170121
8.
Lun
,
Y.
,
Lin
,
L.
,
He
,
H.
,
Ye
,
X.
,
Zhu
,
Z.
, and
Wei
,
Y.
,
2019
, “
Effects of Vortex Structure on Performance Characteristics of a Multiblade Fan With Inclined Tongue
,”
Proc. Inst. Mech. Eng., Part A
,
233
(
8
), pp.
1007
1021
.10.1177/0957650919840964
9.
González
,
J.
,
Oro
,
J. M. F.
,
Delgado
,
L.
,
Méndez
,
D.
,
Argüelles
,
K. M.
,
Velarde-Suárez
,
S.
, and
Rodríguez
,
D.
,
2019
, “
Symmetrized Dot Pattern Analysis for the Unsteady Vibration State in a Sirocco Fan Unit
,”
Appl. Acoust.
,
152
, pp.
1
12
.10.1016/j.apacoust.2019.03.017
10.
González
,
J.
,
Delgado
,
L.
,
Velarde-Suárez
,
S.
,
Fernández-Oro
,
J. M.
,
Díaz
,
K. M. A.
,
Rodríguez
,
D.
, and
Méndez
,
D.
,
2020
, “
Experimental Study of the Unsteady Vibration Signature for a Sirocco Fan Unit
,”
J. Low Freq. Noise, Vib. Act. Control
,
39
(
1
), pp.
129
148
.10.1177/1461348419837418
11.
Xu
,
X. G.
,
Liu
,
H. X.
,
Wang
,
S. L.
,
Fan
,
Z. Y.
,
Yang
,
L. J.
, and
Liu
,
S. T.
,
2017
, “
Real-Time Stall Detection of Centrifugal Fan Based on the Analysis of Symmetrized Dot Pattern and Wavelet Packet Transform
,”
J. Vibroengineering
,
19
(
3
), pp.
1823
1832
.10.21595/jve.2017.18072
12.
Witte
,
M.
,
Torner
,
B.
, and
Wurm
,
F. H.
,
2018
, “
Analysis of Unsteady Flow Structures in a Radial Turbomachine by Using Proper Orthogonal Decomposition
,”
ASME
Paper No. GT2018-76596.10.1115/GT2018-76596
13.
Yang
,
X.
,
Zhu
,
X.
,
Hu
,
C.
, and
Du
,
Z.
,
2018
, “
Compressed Dynamic Mode Decomposition for the Analysis of Centrifugal Compressor Volute
,”
Int. J. Heat Fluid Flow
,
74
, pp.
118
129
.10.1016/j.ijheatfluidflow.2018.09.013
14.
He
,
X.
,
Fang
,
Z.
,
Rigas
,
G.
, and
Vahdati
,
M.
,
2021
, “
Spectral Proper Orthogonal Decomposition of Compressor Tip Leakage Flow
,”
Phys. Fluids
,
33
(
10
), p.
105105
.10.1063/5.0065929
15.
Pan
,
C.
,
Xue
,
D.
,
Xu
,
Y.
,
Wang
,
J.
, and
Wei
,
R.
,
2015
, “
Evaluating the Accuracy Performance of Lucas-Kanade Algorithm in the Circumstance of PIV Application
,”
Sci. China: Phys., Mech. Astron.
,
58
(
10
), pp.
1
16
.10.1007/s11433-015-5719-y
16.
Lumley
,
J. L.
,
1967
, “
The Structure of Inhomogeneous Turbulent Flows
,”
Atmospheric Turbulence and Radio Wave Propagation
, pp.
166
178
.
17.
Sirovich
,
L.
,
1987
, “
Turbulence and the Dynamics of Coherent Structures, Part 1: Coherent Structures
,”
Q. Appl. Math.
,
45
(
3
), pp.
561
571
.10.1090/qam/910462
18.
Schmidt
,
O. T.
, and
Colonius
,
T.
,
2020
, “
Guide to Spectral Proper Orthogonal Decomposition
,”
AIAA J.
,
58
(
3
), pp.
1023
1033
.10.2514/1.J058809
19.
Nekkanti
,
A.
, and
Schmidt
,
O. T.
,
2021
, “
Frequency–Time Analysis, Low-Rank Reconstruction and Denoising of Turbulent Flows Using SPOD
,”
J. Fluid Mech.
,
926
, p.
A26
.10.1017/jfm.2021.681
20.
Pan
,
C.
,
Wang
,
H.
, and
Wang
,
J.
,
2013
, “
Phase Identification of Quasi-Periodic Flow Measured by Particle Image Velocimetry With a Low Sampling Rate
,”
Meas. Sci. Technol.
,
24
(
5
), p.
055305
.10.1088/0957-0233/24/5/055305
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