For experimental investigations of the thermodynamic effect on a cavitating inducer, it is nesessary to observe the cavitation. However, visualizations of the cavitation are not so easy in cryogenic flow. For this reason, we estimated the cavity region in liquid nitrogen based on measurements of the pressure fluctuation near the blade tip. In the present study, we focused on the length of the tip cavitation as a cavitation indicator. Comparison of the tip cavity length in liquid nitrogen $(80K)$ with that in cold water $(296K)$ allowed us to estimate the strength of the thermodynamic effect. The degree of thermodynamic effect was found to increase with an increase of the cavity length. The temperature depression was estimated from the difference of the cavitation number of corresponding cavity condition (i.e., cavity length) between in liquid nitrogen and in cold water. The estimated temperature depression caused by vaporization increased rapidly when the cavity length extended over the throat. In addition, the estimated temperature inside the bubble nearly reached the temperature of the triple point when the pump performance deteriorated.

1.
Stahl
,
H. A.
, and
Stepanoff
,
A. J.
, 1956, “
Thermodynamic Aspects of Cavitation in Centrifugal Pumps
,”
ASME J. Basic Eng.
0021-9223,
78
, pp.
1691
1693
.
2.
Franc
,
J. P.
,
Rebattet
,
C.
, and
Coulon
,
A.
, 2004, “
An Experimental Investigation of Thermal Effect In a Cavitating Inducer
,”
ASME J. Fluids Eng.
0098-2202,
126
, pp.
716
723
.
3.
Yoshida
,
Y.
,
Tsujimoto
,
Y.
,
Kamijo
,
K.
, and
Maekawa
,
Y.
, 1997, “
,”
Proceedings of the 5th Asian International Conference on Fluid Machinery
, Oct. 1997,
Seoul, Korea
, pp.
457
464
.
4.
Yoshida
,
Y.
,
Watanabe
,
M.
,
Hashimoto
,
H.
,
Shimagaki
,
M.
,
,
H.
, and
Shimura
,
T.
, 2004, “
Verification Results of Cryogenic Inducer Test Facility in JAXA
,” (in Japanese),
Proceedings JSME Fluids Engineering Conference
, Nov. 2004,
Fukuoka, Japan
, OS-12-6, No. 127.
5.
Stepanoff
,
A. J.
, 1964, “
Cavitation Properties of Liquids
,”
ASME J. Eng. Power
0022-0825,
86
, pp.
195
200
.
6.
Yoshihara
,
K.
,
Kato
,
H.
,
Yamaguchi
,
H.
, and
Miyanaga
,
M.
, 1988, “
Experimental Study on the Internal Flow of a Sheet Cavity
,”
Proceedings Cavitation and Multiphase Flow Forum
, July, 1988,
Cincinnati, Ohio
, ASME, FED-Vol.
64
, pp.
94
98
.
7.
Brennen
,
C. E.
, 1973, “
The Dynamic Behavior and Compliance of a Stream of Cavitating Bubbles
,”
J. Fluids Eng.
0098-2202,
98
, pp.
533
541
.