Jökull - 01.12.1966, Blaðsíða 36

i. Exrr
dlflH£T&Z.
ÖRTfí FRDM WELLS f)T HVEfíFáERD!t UELRND
DESIáNRTioM OF li/ELU 07 08
UNCfíSEÖ SofíB, /M. 8%L 8 83/4
TfíPEfí EY/T DlfíHETEfí, /M, 63/4 6% lo3//(,
WELL. HEfíD PRESSUfíE, fw LS/lN <5. /or 94 78 99 10 8Z 87
CRlTicfíL PfíESSURE, pc , LS//HZ <8. 8e 8/ 7o 3Z 7r Sá Sr
8fíSE TEMPEfífíTufí.E, °F" 421 422. 437 437 437 411 421
CfíLCULfíTED E%ir OfíyA/ESS FfífíCTioM , X o-tiA o-nc, 0-144 0-/34 0-140 0-137 0-/38
ESTlHfíTED HfíSS FLOvJ £/$m/sE<Z /34 t4o /3o //4 <2.1 2/7 U7
Hfíss Fioy. , <5, Lð/sEC'FT2, S~4t T6S SZ4 4S9 471 384 384
TftBLE I ( REPAoöuceD FAori fíYí£yy /fÁ4 )
entropy and adjusting yield the working equa-
tion
The derivatives (3vf/3p)g and (3vg/3p)g can, in
theory, be calculated from the tabulated pro-
perties of steam, provided physical meanings
can be attributed to the slopes. The derivative
(3Rg/3p)g can be calculated from data on void
fractions given by Martinelli (1949) in the
manner described by Isbin et al. A better
method is to employ void fraction data given
by Fauske (1962) as defined in equation (13)
below.
In equation (8), (3x/3p)g may be evaluated
from a knowledge of the base temperature and
the assumed local static pressure. The remain-
ing properties and the derivatives refer to the
observed critical pressure at exit. The predicted
flow can thus be calculated. The method has
not proved satisfactory as it seriously under-
estimates the flow.
(iii) Homogeneous Flow Methods
This familiar elementary method is deserving
of mention if only to complete the list. It is
based on the assumption that no slip occurs
between liquid and vapour, and it is thus of
no consequence how the phases are associated.
The discharge is given by the standard expres-
sion
190 JÖKULL