Volutes for radial-flow turbomachines (e.g., centrifugal fans and pumps) are spiral funnel-shaped casings that house rotors. Their function is to guide the flow from rotors to outlets and maintain constant flow speeds. Under specific conditions, however, volutes are removed (termed voluteless) to reduce flow losses and noise. In this paper, a generic voluteless centrifugal fan is investigated for the tonal noise generation at an off-design operation point. In contrast to typical tonal noise sources induced by the fan blades, we find out that another predominant source is the turbulence stemming from the clearance gap between the fan front shroud and the inlet duct. The turbulence evolves along with the front shroud and is swept downstream to interact with the top side of the blade leading edge. An obvious additional tone is observed at 273Hz other than the blade passing frequency (BPF0) and relevant harmonic frequencies. By coarsening the mesh resolution near the inlet gap and front shroud in the simulations, we artificially deactivate the gap turbulence. Consequently, the tone at 273Hz disappears completely. The finding indicates that the interaction between the gap turbulence and blades accounts for the tone. As the gap turbulence exists near the front shroud, this rotating wall introduces rotational momentum into the turbulence due to skin friction. Hence, this tonal interaction frequency is smaller than BPF0 with a decrement of the fan rotation frequency. To the authors' knowledge, this is the first time that voluteless centrifugal fans are studied for the gap-turbulence noise generation.

1.
B.
Berglund
,
T.
Lindvall
, and
D.
Schwela
, “
New guidelines for community noise
,”
Noise Vib. Worldwide
31
,
24
29
(
2000
).
2.
M.
Azimi
, “
Noise reduction in buildings using sound absorbing materials
,”
J. Archit. Eng. Technol.
6
,
198
(
2017
).
3.
L. M.
Wang
and
C. C.
Novak
, “
Human performance and perception-based evaluations of indoor noise criteria for rating mechanical system noise with time-varying fluctuations
,”
ASHRAE Trans.
116
,
553
568
(
2010
).
4.
V.
Pommier-Budinger
and
O.
Cherrier
, “
Baffle silencer with tunable resonators for adaptive control of variable tonal noise
,”
J. Vib. Control
21
,
1801
1809
(
2015
).
5.
J. E.
Ffowcs Williams
and
D. L.
Hawkings
, “
Theory relating to the noise of rotating machinery
,”
J. Sound Vib.
10
,
10
21
(
1969
).
6.
R.
Schäfer
and
M.
Böhle
, “
Validation of the lattice Boltzmann method for simulation of aerodynamics and aeroacoustics in a centrifugal fan
,”
Acoustics
2
,
735
752
(
2020
).
7.
J.
Zhang
,
W.
Chu
,
J.
Zhang
, and
Y.
Lv
, “
Vibroacoustic optimization study for the volute casing of a centrifugal fan
,”
Appl. Sci.
9
,
859
(
2019
).
8.
D.
Wolfram
and
T. H.
Carolus
, “
Experimental and numerical investigation of the unsteady flow field and tone generation in an isolated centrifugal fan impeller
,”
J. Sound Vib.
329
,
4380
4397
(
2010
).
9.
M.
Sanjose
and
S.
Moreau
, “
Direct noise prediction and control of an installed large low-speed radial fan
,”
Eur. J. Mech.
61
,
235
243
(
2017
).
10.
F.
Pérot
,
F. M. S.
Kim
,
V. L.
Goff
,
X.
Carniel
,
Y.
Goth
, and
C.
Chassaignon
, “
Numerical optimization of the tonal noise of a backward centrifugal fan using a flow obstruction
,”
Noise Control Eng. J.
61
,
307
319
(
2013
).
11.
J. S.
Choi
,
D. K.
McLaughlin
, and
D. E.
Thompson
, “
Experiments on the unsteady flow field and noise generation in a centrifugal pump impeller
,”
J. Sound Vib.
263
,
493
514
(
2003
).
12.
C.
Hariharan
and
M.
Govardhan
, “
Effect of inlet clearance on the aerodynamic performance of a centrifugal blower
,”
Int. J. Turbo Jet Engines
33
,
215
228
(
2016
).
13.
Y.
Lee
, “
Impact of fan gap flow on the centrifugal impeller aerodynamics
,”
J. Fluids Eng.
132
,
1
9
(
2010
).
14.
Y.
Lee
,
V.
Ahuja
,
A.
Hosangadi
, and
R.
Birkbeck
, “
Impeller design of a centrifugal fan with blade optimization
,”
Int. J. Rotating Mach.
2011
,
537824
.
15.
M.
Ottersten
,
H.-D.
Yao
, and
L.
Davidson
, “
Numerical and experimental study of tonal noise sources at the outlet of an isolated centrifugal fan
,” arXiv:2011.13645 (
2020
).
16.
M.
Ubaldi
,
P.
Zunino
, and
A.
Cattanei
, “
Relative flow and turbulence measurements downstream of a backward centrifugal impeller
,”
J. Turbomach.
115
,
543
551
(
1993
).
17.
M. W.
Johnson
and
J.
Moore
, “
The development of wake flow in a centrifugal impeller
,”
J. Eng. Power
102
,
382
389
(
1980
).
18.
L.
Mongeau
,
D.
Thompson
, and
D.
McLaughlin
, “
Sound generation by rotating stall in centrifugal turbomachines
,”
J. Sound Vib.
163
,
1
30
(
1993
).
19.
Y. H.
Yu
, “
Rotor blade-vortex interaction noise
,”
Prog. Aerosp. Sci.
36
,
97
115
(
2000
).
20.
R.
Schaefer
and
M.
Boehle
, “
Influence of the mesh size on the aerodynamic and aeroacoustics of a centrifugal fan using lattice-Boltzmann method
,” in
23rd International Congress on Acoustics in Aachen
(
ICA
,
2019
), pp.
1882
1889
.
21.
M.
Sanjosè
,
S.
Hub
,
F.
Lörcher
, and
S.
Moreau
, “
Noise mechanisms in a radial fan without volute
,”
J. Phys.: Conf. Ser.
1909
,
012009
(
2021
).
22.
M. L.
Shur
,
P. R.
Spalart
,
M. K.
Strelets
, and
A. K.
Travin
, “
A hybrid RANS-LES approach with delayed-DES and wall-modelled LES capabilities
,”
Int. J. Heat Fluid Flow
29
,
1638
1649
(
2008
).
23.
M.
Ottersten
,
H.-D.
Yao
, and
L.
Davidson
, “
Unsteady simulation of tonal noise from isolated centrifugal fan
,” engrXiv (
2020
).
24.
M.
Sanjose
and
S.
Moreau
, “
Numerical simulations of a low-speed radial fan
,”
Int. J. Eng. Syst. Modell. Simul.
4
,
47
58
(
2012
).
25.
A.
Rynell
,
G.
Efraimsson
,
M.
Chevalier
, and
M.
Åbom
, “
Inclusion of upstream turbulent inflow statistics to numerically acquire proper fan noise characteristics
,” SAE Paper No. 2016-01-1811 (
2016
).
26.
A.
Rynell
,
M.
Chevalier
,
M.
Åbom
, and
G.
Efraimsson
, “
A numerical study of noise characteristics originating from a shrouded subsonic automotive fan
,”
Appl. Acoust.
140
,
110
121
(
2018
).
27.
B.
Hu
,
H.
OuYang
,
Y.
Wu
,
G.
Jin
,
X.
Qiang
, and
Z.
Du
, “
Numerical prediction of the interaction noise radiated from axial fan
,”
Appl. Acoust.
74
,
544
552
(
2013
).
28.
National Instruments Corporation,
LabVIEW Sound and Vibration Analysis Manuals (Version 17.0.0)
(
National Instruments Corporation
,
2017
).
29.
Siemens PLM Software
,
STAR-CCM+ User Guide (Version 12.04)
(
Siemens PLM Software
,
2017
).
30.
H.-D.
Yao
and
L.
Davidsson
, “
Vibro-acoustics response of simplified glass window excited by the turbulent wake of a quarter-spherocylinder body
,”
J. Acoust. Soc. Am.
145
,
3163
3176
(
2019
).
31.
S.
Salunkhe
,
O.
Fajri
,
S.
Bhushan
,
D.
Thompson
,
D.
O'Doherty
,
T.
O'Doherty
, and
A.
Mason-Jones
, “
Validation of tidal stream turbine wake predictions and analysis of wake recovery mechanism
,”
J. Mar. Sci. Eng.
7
,
362
(
2019
).
32.
K. S.
Brentner
and
F.
Farassat
, “
Analytical comparison of the acoustic analogy and Kirchhoff formulation for moving surfaces
,”
AIAA J.
36
,
1379
1386
(
1998
).
33.
P.
Spalart
,
S.
Deck
,
M.
Shur
,
K.
Squires
,
M.
Strelets
, and
A.
Travin
, “
A new version of detached-eddy simulation, resistant to ambiguous grid densities
,”
Theor. Comput. Fluid Dyn.
20
,
181
195
(
2006
).
34.
W.
Neise
, “
Review of fan noise generation mechanisms and control methods
,” in
Fan Noise Symposium
(
CETIM
,
France
,
1992
), pp.
45
46
.
35.
O.
Baris
and
F.
Mendonça
, “
Automotive turbocharger compressor CFD and extension towards incorporating installation effects
,” in
Proceedings of the ASME Turbo Expo: Power for Land
, Sea and Air (
2011
).
36.
H.-D.
Yao
,
L.
Davidson
, and
L. E.
Eriksson
, “
Surface integral analogy approaches for predicting noise from 3D high-lift low-noise wings
,”
Acta Mech. Sin.
30
,
326
338
(
2014
).
37.
S.
Salunkhe
,
O. E.
Fajri
,
S.
Bhushane
,
D.
Thompson
,
D.
ÓDohety
,
T.
ÓDohety
, and
A.
Mason-Jones
, “
Validation of tidal stream turbine wake predictions and analysis of wake recovery mechanism
,”
J. Mar. Sci. Eng.
7
,
362
(
2019
).
38.
M.
Tautz
,
Aeroacoustic Noise Prediction of Automotive HVAC System
, FAU Forschungen, Reihre B, Medizin, Naturwissenschaft, Technik Band 27 (
FAU University Press
,
Erlangen
,
2019
).
39.
G.
Cau
,
N.
Mandas
,
G.
Manfrida
, and
F.
Nurzia
, “
Measurements of primary and secondary flows in an industrial forward-curved centrifugal fan
,”
Am. Soc. Mech. Eng.
109
,
353
358
(
1987
).
40.
W. P.
Jones
,
Air conditioning applications and design
, 2nd ed. (
Arnold
,
1997
), pp.
294
295
.
You do not currently have access to this content.