Holding Force Characteristics of Levitation by Jet
from Small Hole of a Levitated Object
Kohei Aono
Graduate School of Engineering
Muroran Institute of Technology
Hokkaido, Japan
20096001@mmm.muroran-it.ac.jp
Manabu Aoyagi
Graduate School of Engineering
Muroran Institute of Technology
Hokkaido, Japan
maoyagi@mmm.muroran-it.ac.jp
Deqing Kong
Graduate School of Engineering
Muroran Institute of Technology
Hokkaido, Japan
kong@muroran-it.ac.jp
Abstract—A jet from a small hole of a cylinder above a
vibrating surface was observed. The cylinder with the hole on
the flat base was levitated between the vibrating surface and
the base. The holding force acted on the levitated cylinder. This
paper reports the holding force with respect to the deviation
distance from the vibrating surface. The holding force
characteristics had a peak with respect to the deviation
distance. The maximum holding force reached about 10 mN.
Keywords—Cylinder,
Levitation, Holding force
Hole,
Jet,
Acoustic
streaming,
I. INTRODUCTION
A planar object on a vibrating surface has been
confirmed to be levitated above the vibrating surface by the
near-field acoustic levitation (NFAL) phenomenon [1-3].
The levitated object was held above the surface by the
holding force because of the viscosity of the air gap between
the object and the vibrating surface. The force had been
estimated at several hundred μN by measuring with the
electromagnetic force balance method[4]. In addition, the jet
from a small hole of a cylinder was observed, as shown in
Fig. 1. This jet was considered to the acoustic streaming
because it was generated during the driving of the vibration
source. The cylinder with a hole was observed to be levitated
from the flat base by the jet ejected toward the base.
Additionally, it was confirmed that the holding force acted
on the levitated cylinder. Fig. 2 shows the behavior of the
levitated cylinder between the vibrating surface and the flat
base by the holding force. This paper reports the results of
force sensor measurements of the holding force in Fig. 2.
Fig. 2. Behavior of the levitated cylinder between the vibrating surface and
the flat base by the holding force.
II. EXPERIMENTAL DEVICES
A. Vibration source
The vibration source in Fig. 3 vibrates vertically on a
resonance frequency of 28 kHz and consists of a duralumin
horn with a vibrating surface diameter of 10 mm and a boltclamped Langevin transducer(BLT).
Fig. 3. Vibration source consisting of BLT and horn.
Fig. 1. Jet (acoustic streaming) by the cylinder with a hole.
B. Driving system of the vibration source
Fig. 4 shows the vibration amplitude constant driving
system. The vibration source in Fig. 3 was driven by this
driving system at a resonance frequency of approximately 28
kHz. The driving system tracked the resonance frequency of
the vibration source during measurements. The AC voltage
amplitude was controlled to adjust the bottom surface
vibration amplitude. Here, instead of the vibration amplitude
A, the bottom surface vibration amplitude A0 of the vibration
source, measured with a laser Doppler vibrometer (LDV),
was input to the amplitude controller.
IV. MEASUREMENT RESULTS
Fig. 4. Vibration amplitude constant driving system.
A. Characteristics by changing vibration amplitude A
Fig. 7 shows the measurement results of the holding force
Fh with respect to the deviation distance x when air gap H =
300 μm constant and vibration amplitude A = 20, 30, 40, and
50 μm. The plot points in Fig. 7 show the average of the
three holding force measurements, and the error bars show
the maximum and minimum values of the three
measurements. h was assumed to be 0 mN when the
cylinder wasn’t levitated from the flat base. The holding
force Fh was increased by increasing A. Fh changed with x
and had a peak with respect to x. The peak distance xp and
the distance x0 at the levitation stop shifted toward the large
deviation distance with increasing A. Fh reached about 10
mN when A = 50 μm and x = 2.5 mm.
III. SETUP FOR MEASUREMENTS
Fig. 5 shows the experimental cylinder and the arranged
cylinder during the measurement. The experimental cylinder
in Fig. 5(a) had a thin wire attached to the side of the
cylinder with the adhesive tape. The wire was connected to
the force sensor (M5-012 Series 5 Force Gauge, Mark-10
Corporation). The cylinder has a 1 mm diameter through
hole at its center. The material of the cylinder part is
duralumin, and its thickness is 5 mm. The cylinder was
arranged between the vibrating surface and the flat surface
during the measurement, as shown in Fig. 5(b). Fig. 6 shows
the setup for the measurement of the holding force and
parameters. The force sensor was set to the same height as
the cylinder. The deviation distance x from the vibrating
surface was changed by moving the force sensor on the
linear stage. The air gap H was adjusted by a laser
displacement meter. The holding force Fh on the cylinder
was measured with the force sensor via the thin wire.
Fig. 7. Holding force Fh vs. deviation distance x when air gap H = 300 µm.
B. Characteristics by changing air gap H
Fig. 8 shows the measurement results of the holding force
Fh with respect to the deviation distance x when air gap H =
200, 300, 400, and 500 μm and vibration amplitude A = 40
μm constant. Fh increased by increasing H. xp shifted toward
the large deviation distance with increasing H. However, x0
did not shift with increasing H.
Fig. 5. Cylinder details : (a) The experimental cylinder. (b) During
measurement.
Fig. 8. Holding force Fh vs. deviation distance x when A = 40 µm.
V. SUMMARY
Fig. 6. Setup for the measurement of the holding force, and parameters.
The cylinder with a small hole placed between the
vibrating surface and the flat base was observed to be held
under the vibrating surface. The holding force on the
cylinder was measured by the force sensor. The force has a
peak with respect to the deviation distance from the vibrating
surface. When the vibration amplitude was 50 μm, the air
gap was 300 μm, and the deviation distance was 2.5 mm, the
force reached about 10 mN. The holding force of the cylinder
with the hole was several hundred times larger than that of
NFAL. In future work, the mechanism of such a levitation
phenomenon by the cylinder with a small hole will be
clarified by measurements and analysis.
ACKNOWLEDGMENT
This work was partially supported by JSPS KAKENHI
Grant Number JP21H01268 and JST SPRING Grant
Number JPMJSP2153.
REFERENCES
[1]
[2]
[3]
[4]
S. Ueha, Y.Hashimoto, and Y. Koike, “Non-contact transportation
using near-field acoustic levitation”, Ultrasonics 38, 26, 2000, in press.
T. Amano, Y. Koike, K. Nakamura, S. Ueha, and Y. Hashimoto, “A
multi-transducer near field acoustic levitation system for noncontact
transportation of large-sized planar objects”, Jpn. J. Appl. Phys. 39,
2982, 2000, in press
H. Nomura, T. Kamakura, and K. Matsuda, “Theoretical and
experimental of near-field acoustic levitation”, J. Acoust. Soc. Am.
111, 1578, 2002, in press.
K. Aono, and M. Aoyagi, “Measurement of Holding Force and
Transportation Force Acting on Tabular Object in Near-Field
Acoustic Levitation”, IEEE Trans. ultrason. ferroelectr. freq. control,
69, 4, 2022, in press.