Proceedings of the 8th International Symposium on cavitation
NO. 36 (CAV2012)
August 14-16, 2012, Singapore
Experimental Study of Ventilated
Supercavity on an Axisymmetric Model
Zhi Wang, Xiaoxing Peng, Kai Yan, Xuesen Chu,
Weizheng Chen, Guang Feng
China Ship Scientific Research Center
Wuxi, Jiangsu, P. R. China
1 Introduction

Supercavitation can be used to reduce
drag.
Key: Generation and Control
 Condition: High speed and Ventilation


In this paper:
Experimentally studied axisymmetric body
with various cavitators;
 Supercavities were generated by artificial
ventilation.

2 Experimental facility and model
Large cavitation water tunnel at
CSSRC




Testing section: F800mm×L3200mm;
Speed range: 0~20m/s;
Pressure range: 5~400 kPa;
Lowest natural cavitation number: 0.15.
E
W ater P um p
P ressure
P um p
38000

12000
T esting section
( F 800m m × L 3200m m )
26920
V acuum
P um p
2 Experimental facility and model


The cavitator diameters
Dn : 14.3, 16, 20 and
25mm.
The cavitator incidence
angles: 5o, 10o and 15o.

o
W all of W ater T unnel
P ressure S ensing
C avitator H oles
T ail S trut
V entilating R ings
Sketch of testing model and installation
y
x
Cavitator incidence angle
Cavitators
3 Experimental results
3.1 Similarity Parameters

Ventilated cavitation number (represent the scale of the ventilated
cavity)
c 
P  Pc
1
2

 V 
2
Froude Number (represent the gravity effect on the cavity)
V
Fr 
gD n

Natural cavitation number (represent the incoming flow condition)
v 
P  Pv
1
2
 V 
2
3 Experimental results
3.2 The influence of cavitator size (Dn) on
supercavity shape
D n  14.3m m
D n  16m m
D n  20mm
D n  25m m
Dn / Dm
0.19
0.21
0.26
0.33
Dc / Dm
1.12
1.16
1.21
1.39
3 Experimental results
3.3 The influence of incidence angles of cavitator
() on supercavity shape
“Down wash” of the cavity
 0
 5
  10
  15
3 Experimental results
3.4 The influence of ventilated cavitation number
(c ) on supercavity shape
c =0.068
c =0.066
c =0.064
c =0.062
3 Experimental results
3.5 The influence of Froude (Fr) number on
supercavity shape
Fr=24.0
Fr=32.1
Fr=40.1
3 Experimental results
3.6 Supercavity shapes under different shot mode
Ordinary light, shot with digital camera
Stroboscopic light, shot with digital camera
Ordinary light, 5000 f/s high-speed video camera
4 Conclusions

Various factors that can influence ventilated supercavity
shapes were tested experimentally in cavitation tunnel.





Though the cavity lengths are nearly the same the cavity is
growing thicker as Dn becomes larger.
The “down wash” phenomenon is more evident when the
cavitator incidence angle  becomes larger.
When ventilating air rate increases, the ventilated cavitation
number goes down, then both the length and the largest
diameter of the supercavity increase.
As the Froude number Fr increases the floating-up
phenomenon is weakened.
The surface of the supercavity is smooth or rough, depends on
light source and camera.
THANKS !!