Combustor element changes area between DESIGN and OFF-DESIGN points #74
Description
I first checked if there were any open issues regarding matching design and off-design combustor areas and was going to push a PR myself, when I saw PR#62.
I am documenting here the issue to support that PR.
Descripion
When the exemple given in "pyCycle/example_cycles/high_bypass_turbofan.py" is run, I get the following result, showing a calculated area for DESIGN.burner.Fl_O.stat:area=169.041. Further down in the results, for the Off-Design results, I get OD_part_pwr.burner.Fl_O.sta:area=1550.003 (see excerpt from hbtf_view results file):
----------------------------------------------------------------------------
POINT: DESIGN
----------------------------------------------------------------------------
PERFORMANCE CHARACTERISTICS
Mach Alt W Fn Fg Fram OPR TSFC BPR
0.80000 35000.0 344.303 5900.0 14232.2 8332.2 30.094 0.63072 5.105
------------------------------------------------------------------------------------------------------------------------------------------------
FLOW STATIONS
------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------
Flow Station | tot:P tot:T tot:h tot:S stat:P stat:W stat:MN stat:V stat:area
------------------------------------------------------------------------------------------------------------------------------------------------
DESIGN.fc.Fl_O | 5.273 444.404 -23.983 1.665 3.458 344.303 0.800 778.619 2687.027
DESIGN.inlet.Fl_O | 5.267 444.404 -23.983 1.665 3.623 344.303 0.751 735.912 2750.930
DESIGN.fan.Fl_O | 8.876 524.338 -4.822 1.668 7.687 344.303 0.458 503.511 2388.267
DESIGN.splitter.Fl_O1 | 8.876 524.338 -4.822 1.668 8.302 56.397 0.310 345.152 540.175
DESIGN.splitter.Fl_O2 | 8.876 524.338 -4.822 1.668 7.715 287.906 0.452 497.172 2017.239
DESIGN.duct4.Fl_O | 8.833 524.338 -4.822 1.669 8.256 56.397 0.312 347.007 540.160
DESIGN.lpc.Fl_O | 17.092 641.883 23.430 1.672 16.019 56.397 0.306 376.175 314.644
DESIGN.duct6.Fl_O | 16.919 641.883 23.430 1.673 15.499 56.397 0.356 436.748 278.279
DESIGN.hpc.Fl_O | 158.515 1276.476 180.824 1.689 152.230 49.884 0.244 419.921 52.574
DESIGN.bld3.Fl_O | 158.515 1276.476 180.824 1.689 149.148 41.480 0.300 514.548 36.216
DESIGN.burner.Fl_O | 149.955 2857.000 176.427 1.947 148.948 42.514 0.102 256.960 **169.041**
DESIGN.hpt.Fl_O | 41.484 2052.072 9.419 1.932 38.045 50.918 0.365 776.801 184.766
.
.
.
----------------------------------------------------------------------------
POINT: OD_part_pwr
----------------------------------------------------------------------------
PERFORMANCE CHARACTERISTICS
Mach Alt W Fn Fg Fram OPR TSFC BPR
0.80000 35000.0 344.303 5900.0 14232.2 8332.2 30.094 0.63072 5.105
------------------------------------------------------------------------------------------------------------------------------------------------
FLOW STATIONS
------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------
Flow Station | tot:P tot:T tot:h tot:S stat:P stat:W stat:MN stat:V stat:area
------------------------------------------------------------------------------------------------------------------------------------------------
OD_part_pwr.fc.Fl_O | 5.273 444.404 -23.983 1.665 3.458 344.303 0.800 778.619 2687.027
OD_part_pwr.inlet.Fl_O | 5.267 444.404 -23.983 1.665 3.623 344.303 0.751 735.912 2750.930
OD_part_pwr.fan.Fl_O | 8.876 524.338 -4.822 1.668 7.687 344.303 0.458 503.511 2388.267
OD_part_pwr.splitter.Fl| 8.876 524.338 -4.822 1.668 8.302 56.397 0.310 345.152 540.175
OD_part_pwr.splitter.Fl| 8.876 524.338 -4.822 1.668 7.715 287.906 0.452 497.172 2017.239
OD_part_pwr.duct4.Fl_O | 8.833 524.338 -4.822 1.669 8.256 56.397 0.312 347.007 540.160
OD_part_pwr.lpc.Fl_O | 17.092 641.883 23.430 1.672 16.019 56.397 0.306 376.175 314.644
OD_part_pwr.duct6.Fl_O | 16.919 641.883 23.430 1.673 15.499 56.397 0.356 436.748 278.279
OD_part_pwr.hpc.Fl_O | 158.515 1276.476 180.824 1.689 152.230 49.884 0.244 419.921 52.574
OD_part_pwr.bld3.Fl_O | 158.515 1276.476 180.824 1.689 149.148 41.480 0.300 514.548 36.216
OD_part_pwr.burner.Fl_O| 149.955 2857.000 176.427 1.947 149.943 42.514 0.011 27.879 **1550.003**
OD_part_pwr.hpt.Fl_O | 41.484 2052.072 9.419 1.932 38.045 50.918 0.365 776.801 184.766
Further investigation showed that in class HBTF(pyc.Cycle), the Combustor element is added on line 54 of "high_bypass_turbofan.py":
self.add_subsystem('burner', pyc.Combustor(fuel_type=FUEL_TYPE))
Then, on line 370 of "high_bypass_turbofan.py", class MPhbtf() creates an instance of HBTF (line 298) and on line 370, the pyc_use_default_des_of_conns() method is invoked.
Looking in "mp_cycle.py", where class MPCycle is defined, the method expects a list of default connections for a given element to be in "default_des_od_conns"
Proposed fix:
Add the following to Combustor class' "initialize" method:
self.default_des_od_conns = [
# (design src, off-design target)
('Fl_O:stat:area', 'area')
]
Results:
After implementing this fix, I get the following results from running the same example given in "pyCycle/example_cycles/high_bypass_turbofan.py":
----------------------------------------------------------------------------
POINT: DESIGN
----------------------------------------------------------------------------
PERFORMANCE CHARACTERISTICS
Mach Alt W Fn Fg Fram OPR TSFC BPR
0.80000 35000.0 344.303 5900.0 14232.2 8332.2 30.094 0.63072 5.105
------------------------------------------------------------------------------------------------------------------------------------------------
FLOW STATIONS
------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------
Flow Station | tot:P tot:T tot:h tot:S stat:P stat:W stat:MN stat:V stat:area
------------------------------------------------------------------------------------------------------------------------------------------------
DESIGN.fc.Fl_O | 5.273 444.404 -23.983 1.665 3.458 344.303 0.800 778.619 2687.027
DESIGN.inlet.Fl_O | 5.267 444.404 -23.983 1.665 3.623 344.303 0.751 735.912 2750.930
DESIGN.fan.Fl_O | 8.876 524.338 -4.822 1.668 7.687 344.303 0.458 503.511 2388.267
DESIGN.splitter.Fl_O1 | 8.876 524.338 -4.822 1.668 8.302 56.397 0.310 345.152 540.175
DESIGN.splitter.Fl_O2 | 8.876 524.338 -4.822 1.668 7.715 287.906 0.452 497.172 2017.239
DESIGN.duct4.Fl_O | 8.833 524.338 -4.822 1.669 8.256 56.397 0.312 347.007 540.160
DESIGN.lpc.Fl_O | 17.092 641.883 23.430 1.672 16.019 56.397 0.306 376.175 314.644
DESIGN.duct6.Fl_O | 16.919 641.883 23.430 1.673 15.499 56.397 0.356 436.748 278.279
DESIGN.hpc.Fl_O | 158.515 1276.476 180.824 1.689 152.230 49.884 0.244 419.921 52.574
DESIGN.bld3.Fl_O | 158.515 1276.476 180.824 1.689 149.148 41.480 0.300 514.548 36.216
DESIGN.burner.Fl_O | 149.955 2857.000 176.427 1.947 148.948 42.514 0.102 256.960 **169.041**
DESIGN.hpt.Fl_O | 41.484 2052.072 9.419 1.932 38.045 50.918 0.365 776.801 184.766
.
.
.
----------------------------------------------------------------------------
POINT: OD_part_pwr
----------------------------------------------------------------------------
PERFORMANCE CHARACTERISTICS
Mach Alt W Fn Fg Fram OPR TSFC BPR
0.80000 35000.0 344.303 5900.0 14232.2 8332.2 30.094 0.63072 5.105
------------------------------------------------------------------------------------------------------------------------------------------------
FLOW STATIONS
------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------
Flow Station | tot:P tot:T tot:h tot:S stat:P stat:W stat:MN stat:V stat:area
------------------------------------------------------------------------------------------------------------------------------------------------
OD_part_pwr.fc.Fl_O | 5.273 444.404 -23.983 1.665 3.458 344.303 0.800 778.619 2687.027
OD_part_pwr.inlet.Fl_O | 5.267 444.404 -23.983 1.665 3.623 344.303 0.751 735.912 2750.930
OD_part_pwr.fan.Fl_O | 8.876 524.338 -4.822 1.668 7.687 344.303 0.458 503.511 2388.267
OD_part_pwr.splitter.Fl| 8.876 524.338 -4.822 1.668 8.302 56.397 0.310 345.152 540.175
OD_part_pwr.splitter.Fl| 8.876 524.338 -4.822 1.668 7.715 287.906 0.452 497.172 2017.239
OD_part_pwr.duct4.Fl_O | 8.833 524.338 -4.822 1.669 8.256 56.397 0.312 347.007 540.160
OD_part_pwr.lpc.Fl_O | 17.092 641.883 23.430 1.672 16.019 56.397 0.306 376.175 314.644
OD_part_pwr.duct6.Fl_O | 16.919 641.883 23.430 1.673 15.499 56.397 0.356 436.748 278.279
OD_part_pwr.hpc.Fl_O | 158.515 1276.476 180.824 1.689 152.230 49.884 0.244 419.921 52.574
OD_part_pwr.bld3.Fl_O | 158.515 1276.476 180.824 1.689 149.148 41.480 0.300 514.548 36.216
OD_part_pwr.burner.Fl_O| 149.955 2857.000 176.427 1.947 148.948 42.514 0.102 256.960 **169.041**
OD_part_pwr.hpt.Fl_O | 41.484 2052.072 9.419 1.932 38.045 50.918 0.365 776.801 184.766
Recommendation
Merge PR#62