Combustion, Explosion, and Shock Waves, Vol. 36, No. 6, 2000
Cavitation Bubble
in a Heavy Viscous Liquid
V. N. Rodionov1 UDC 532.528(527)
Translated from Fizika Goreniya i Vzryva, Vol. 36, No. 6, pp. 84 86, November December, 2000.
Original article submitted June 29, 2000.
The motion of a cavitation bubble in a heavy viscous liquid is considered. The re-
sults of filming of the process are analyzed. A laboratory facility for modeling this
phenomenon is described.
The invention of a shaped charge was an impor- uid with a jet penetrating into it. A pipe 50 cm long
tant event in military activity and changed qualita- with an internal diameter of 11 cm was located verti-
tively the ideas of hitting armored machines. How- cally. The butt-end faces of the pipe were covered by
ever, hydrodynamic models that explained the pro- lids; there was a nozzle near the bottom and a branch
cess of jet generation by explosive compression of a pipe for evacuation of air in the upper lid. The liq-
conical metal shell and the mechanism of jet penetra- uid filled part of the volume up to a given level above
tion into an armored plate were even more important the nozzle. The jet was exhausted from the nozzle by
for science and technology. the piston under the action of the compressed spring.
These models were proposed by
M. A. Lavrent ev in clear and explicit form,
which is typical of all classical models of natural
history. Based on the classical models, associative
thinking generates images, which are helpful in
studying natural phenomena in various situations.
Specially or incidentally, all naturalists seek in nature
something born in their imagination. An example of
scientific search of a physical object originating in
G. V. Belyakov s imagination under the influence of
models developed by M. A. Lavrent ev may be the
experiments on generation of a cavitation bubble in
a heavy viscous liquid.
G. V. Belyakov assumed that a fast short jet
penetrating into a liquid under pressure forms a cav-
ity collapsing in the backward part to form another
jet. If the velocity and thickness of the new jet are
not too different from the same characteristics of the
first jet, the resultant bubble can exist autonomously
and move without exciting disturbances in the liquid.
The research experiment was successful: a rapidly
moving cavitation vortex actually appeared in some
experiments [1].
A laboratory facility was designed to find the
conditions of bubble origination in a stationary liq-
Fig. 1. Layout of the facility: 1) nozzle; 2) piston;
1
3) spring; 4) windows; 5) metal cylinder; 6) AKS-
Institute of Geosphere Dynamics, Russian
4 camera; 7) lighter; 8) branch pipe.
Academy of Sciences, Moscow 117334.
0010-5082/00/3606-0751 $25.00 © 2000 Plenum Publishing Corporation 751
752 Rodionov
TABLE 1
x1, mm x2, mm v1, m/sec v2, m/sec l, mm
66 24.2 4.18 1.434 41.8
85.8 31.9 1.98 0.77 52.9
96.8 37.4 1.1 0.55 59.4
106.7 41.8 0.99 0.44 64.9
The length, diameter, and velocity of the jet could Figure 2 shows a stable shape of the cavitation
be varied from one test to another. Optical registra- bubble ascending in a heavy liquid. The coordinates
tion of the bubble was performed through two long and velocities of the bubble apex (v1) and backward
windows located opposite each other along the pipe. surface (v2) were measured. These data are listed in
One window 2.5 cm wide was illuminated by scat- Table 1. It is not possible to measure the jet diam-
tered light, and the filming was performed through eter in the photographs, since the refraction of light
the other window 3.5 cm wide. Figure 1 shows the beams in the bubble distorts the size of the jet and
working volume of the facility. (The cross section is objects located behind the bubble. The external con-
shown in the central part, in the brakes.) tours of the bubble itself on the background of the
The test conditions and results of one ex- illuminated window are not distorted (Fig. 3).
periment are presented below. Glycerin [density The energy of the bubble is proportional to the
1.26 g/cm3 and viscosity 20 g/(cm·sec)] filled the pipe product of its volume and the pressure in the ambi-
up to a level of 15 cm above the nozzle. A jet 1 cm in ent liquid. For a constant energy, the bubble volume
diameter and 2.5 cm long was  shot with a velocity is inversely proportional to the pressure in the liquid.
of 4.5 m/sec. The gas pressure above the glycerin The resistance to bubble motion is caused by the vis-
surface was about 10-4 atm. The filming frequency
was 100 frames per second. The experimental facil-
ity allows one to organize conditions necessary for a
cavitation bubble to appear and autonomously exist
for some time.
Fig. 2. Stable shape of the cavitation bubble in a heavy
liquid
Fig. 3. Photograph of the cavitation bubble.
Cavitation Bubble in a Heavy Viscous Liquid 753
cosity of the liquid, which is mainly manifested in Under favorable conditions, the bubble may
local zones of the forward and backward parts of the cover a large distance and transfer some part of the
bubble. Because of this, the energy losses of the bub- substance of the initiating jet, since the exchange of
ble are significantly lower than the losses of a solid substance between the bubble and the ambient liquid
body of the same size. is rather limited.
Ascending in the field of gravity, the bubble may The experimental results presented demonstrate
increase its energy if energy losses are reduced. Sim- the formation and autonomous motion of a cavitation
ilarly, the bubble energy increases if it moves in the bubble inside the laboratory facility. The mechani-
direction of the accelerated motion of the vessel con- cal image of the bubble is quite clear for construct-
taining the liquid. After losing its energy, the bubble ing models and studying them theoretically in detail.
ceases to exist. This image may be realized in various natural phe-
nomena and in various media.
REFERENCES
1. M. A. Sadovskii, V. N. Rodionov, and G. V. Belyakov,
 Mechanics of origination of a cavitation bubble,
Dokl. Ross. Akad. Nauk, 325, No. 1, 42 45 (1992).