The discharge coefficients of critical Venturi nozzles were measured for CO2 and SF6 on the Reynolds number range from 3×103 to 2×105. The results showed that the measured discharge coefficients for both gases were about 2 percent larger than the theoretical estimation based on the assumption of isentropic flow of a perfect gas and this large deviation could not be reduced even by introducing real gas effects. The experimental results also showed that the large deviation for CO2 could be explained through the assumption of a nonequilibrium flow at the throat. On the other hand, the reason of the deviation observed for SF6 has not been clear yet, but one possible explanation would be the inadequate estimation of the boundary layer at the throat because the theory is based on the laminar boundary layer of a perfect gas. [S0098-2202(00)02004-6]

Issue Section:
Technical Papers
Keywords:
nozzles, flow measurement, instruments, nonequilibrium flow, boundary layers, measurement errors
Topics:
Carbon dioxide, Discharge coefficient, Flow (Dynamics), Nozzles, Venturi tubes, Boundary layers, Nonequilibrium flow
1.
Nakao
,
S.
, and
Takamoto
,
M.
,
1999
, “
Development of the Calibration Facility for Small Mass Flow rates of Gases and the Sonic Venturi Nozzle Transfer Standard
,”
JSME, Series B
,
42
, pp.
667
–
673
.
2.
Ishibashi, M., Takamoto, M., and Nakao, Y., 1994, “Precise Calibration of Critical Nozzles of Various Shapes at the Reynolds Number of 0.8−2.5×105,” FLOMEKO’94, Glasgow, Session 6.
3.
Geropp, D., 1971, “Laminare Grenzschichten in ebenen und rotationssymmetrischen Lavalduesen,” Deutsche Luft und Raumfahrt Forschungsbericht (in Germany).
4.
Ishibashi, M. and Takamoto, M., 1997, “Very Accurate Analytical Calculation of the Discharge Coefficients of Critical Venturi Nozzles with Laminar Boundary Layer,” Proceedings of FLUCOME, Japan.
5.
Hall
,
I. M.
,
1962
, “
Transonic Flow in Two Dimensional and Axially Symmetric Nozzles
,”
Q. J. Mech. Appl. Math.
,
15
, pp.
487
–
508
.
6.
Nakao, S., Hirayama, T., Yokoi, Y., and Takamoto, M., 1997, “Effects of Thermalphysical Properties of Gases on the Discharge Coefficients of the Sonic Venturi Nozzle,” Proc. 1997 ASME FED Summer Meeting, Vancouver, Canada.
7.
International Standard ISO 9300, 1990, “Measurement of gas flow by means of critical flow Venturi nozzles,” p. 8.
8.
Tang
,
S. P.
, and
Fenn
,
J. B.
,
1978
, “
Experimental Determination of the Discharge Coefficients for Critical Flow Through as Axisymmetric Nozzle
,”
AIAA J.
,
16
, pp.
41
–
46
.
9.
JSME Data Book, 1986, Thermophysical Properties, edited by Japan Society of Mechanical Engineers (in Japanese).
10.
Johnson
,
R. C.
,
1964
, “
Calculations of Real-Gas Effects in Flow Through Critical-Flow Nozzles
,”
ASME J. Basic Eng., Series D
,
86
, Sept., pp.
519
–
526
.
11.
Levine, R. D., and Bernstein, R. B., 1974, Molecular Reaction Dynamics, Oxford University Press (1997: translated in Japanese).
12.
Simpson
,
C. J. S. M.
,
Bridgman
,
K. B.
, and
Chandler
,
T. R. D.
,
1968
, “
Shock-Tube Study of Vibrational Relaxation in Carbon Dioxide
,”
J. Chem. Phys.
,
49
, pp.
513
–
522
.
13.
Liepmann, H. W., and Roshko, A, 1960, Elements of Gasdynamics, Wiley, New York (1983: translated in Japanese).
14.
Yokogawa, A., and Nishioka, M., 1999, “Numerical Studies on the Sonic Nozzle for Mass Flow Calibration,” Ms. thesis, Univ. of Osaka-prefecture (in Japanese).
15.
Johnson
,
A.
,
Wright
,
J.
,
Nakao
,
S.
,
Merkle
,
C. L.
, and
Moldover
,
M. R.
,
1999
, “
The Effect of Vibrational Relaxation on the Discharge Coefficient of Critical Flow Ventur
,”
Flow Meas. Instrum.
,
11
, pp.
315
–
327
.
16.
Back
,
L. H.
,
1970
, “
Acceleration and Cooling Effects in Laminar Boundary layers-Subsonic, Transonic, and Supersonic Speeds
,”
AIAA J.
,
8
, pp.
794
–
802
.
Copyright © 2000
 by ASME
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