 
 
 
 
 
 
 
  
In a split the flow from a gas pipe is split and redirected through two other pipes. So in principal three network elements of type GAS PIPE have one node in common in a split. The fluid elements of type BRANCH SPLIT represent the extra energy loss due to the splitting of the flow and have to be inserted in the outward branches of the split. This is represented schematically in Figure 89. The filled circles represent corner nodes of the fluid elements, the others are the midside nodes. For a split to work properly the flow direction must be as indicated in Figure 89. If the solution of the equation system indicates that this is not the case appropriate measures must be taken. For instance, if the solution reveals that there are two inward flows and one outward flow, branch joint elements must be selected.
Several types of geometry are available.
A branch split of type GE [73], Figure 90, is quite general and allows arbitrary cross sections and angles (within reasonable limits). It is characterized by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=BRANCH SPLIT GE card):
 of branch 0.
 of branch 0.
 of branch 1.
 of branch 1.
 of branch 2.
 of branch 2.
 (
 ( ).
).
 (
 ( ).
).
A branch split of type Idelchik1, Figure 91, can be used if the incoming branch is continued in a straight way and does not change its cross section [33]. It is characterized by the following constants (to be specified in that order on the line beneath the *FLUID SECTION, TYPE=BRANCH SPLIT IDELCHIK1 card):
 of branch 0.
 of branch 0.
 of branch 0.
 of branch 0.
 of branch 2.
 of branch 2.
 .
.
 (
 ( ).
).
 of
 of  .
.
 of
 of  .
.
 -correction factor
-correction factor  for branch 1  (
 for branch 1  (
 ). This allows to tune the
). This allows to tune the  value with experimental evidence
  (default is 1).
 value with experimental evidence
  (default is 1).
 -correction factor
-correction factor  for branch 2  (
 for branch 2  (
 ). This allows to tune the
). This allows to tune the  value with experimental evidence (default is 1).
 value with experimental evidence (default is 1).
A branch split of type Idelchik2, Figure 92, is used if the
outward branches make an angle of  with the incoming branch [33]. It
is characterized by the following constants (to be specified in that order on
the line beneath the *FLUID SECTION, TYPE=BRANCH SPLIT
IDELCHIK2 card):
 with the incoming branch [33]. It
is characterized by the following constants (to be specified in that order on
the line beneath the *FLUID SECTION, TYPE=BRANCH SPLIT
IDELCHIK2 card):
 of branch 0.
 of branch 0.
 of branch 1.
 of branch 1.
 of branch 2.
 of branch 2.
 .
.
 .
.
 -correction factor
-correction factor  for branch 1  (
 for branch 1  (
 ). This allows to tune the
). This allows to tune the  value with experimental evidence (default is 1).
 value with experimental evidence (default is 1).
 -correction factor
-correction factor  for branch 2  (
 for branch 2  (
 ). This allows to tune the
). This allows to tune the  value with experimental evidence (default is 1).
 value with experimental evidence (default is 1).
By specifying the parameter LIQUID on the *FLUID SECTION card the loss is calculated for liquids. In the absence of this parameter, compressible losses are calculated.
Example files: branchsplit1, branchsplit2, branchsplit3.
 
 
 
 
 
 
