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Reject inconsistent propulsion edge power #88

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Reject inconsistent propulsion edge power #88

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f613377
Check propulsion edge power consistency
triet228 Sep 16, 2026
f9cd183
Fix multi-engine parallel connections
triet228 Sep 17, 2026
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62 changes: 62 additions & 0 deletions +PropulsionPkg/CheckEdgePowerConsistency.m
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@@ -0,0 +1,62 @@
function [] = CheckEdgePowerConsistency(Arch, LamUps, LamDwn, EtaUps, EtaDwn, SinkPower)
%
% [] = CheckEdgePowerConsistency(Arch, LamUps, LamDwn, EtaUps, EtaDwn, SinkPower)
% written by Triet Ho
% last updated: 16 sep 2026
%
% Check that upstream and downstream matrices describe the same power on
% every active edge at one mission control point. Downstream propagation
% gives the component powers needed to meet the sink demand. Each edge's
% delivered power must then agree with upstream propagation from its source.
%
% INPUTS:
% Arch - source-to-target propulsion architecture matrix.
% size/type/units: n-by-n / logical or double / []
% LamUps - evaluated upstream operational matrix.
% size/type/units: n-by-n / double / []
% LamDwn - evaluated downstream operational matrix.
% size/type/units: n-by-n / double / []
% EtaUps - upstream edge efficiencies.
% size/type/units: n-by-n / double / []
% EtaDwn - downstream edge efficiencies.
% size/type/units: n-by-n / double / []
% SinkPower - power required at the final sink.
% size/type/units: 1-by-1 / double / [W]
%
% OUTPUTS:
% none; throws an error when an edge is inconsistent.
%

% An infinite demand is handled by PropAnalysis as an infeasible mission
% point, so it has no finite edge flow to compare.
if (isinf(SinkPower))
return;
end

% Use the same downstream propagation as the mission analysis, including
% path losses, to recover power at every component from the sink demand.
ncomp = length(Arch);
Power = zeros(ncomp, 1);
Power(end) = SinkPower;
Power = PropulsionPkg.PowerFlow(Power, Arch', LamDwn, EtaDwn, -1);

% Compare delivered power on each source-to-target edge. The downstream
% split is a fraction of target demand; the upstream split is a fraction
% of source power and must include the upstream edge efficiency.
[Source, Target] = find(Arch);
DownIndex = sub2ind([ncomp, ncomp], Target, Source);
UpIndex = sub2ind([ncomp, ncomp], Source, Target);
DownEdge = Power(Target) .* LamDwn(DownIndex);
UpEdge = Power(Source) .* LamUps(UpIndex) .* EtaUps(UpIndex);

% Match PowerFlow's 1e-6 W convergence floor while allowing small
% relative rounding error at large power. Row sums alone cannot detect
% mismatched individual edge flows.
Tolerance = max(1.0e-06, 1.0e-08 * max(abs(DownEdge), abs(UpEdge)));
if (any(~isfinite(DownEdge)) || any(~isfinite(UpEdge)) || ...
any(abs(DownEdge - UpEdge) > Tolerance))
error("FAST:EdgePowerInconsistent", ...
"Edge power is not consistent. Your power splits are over-constrained.");
end

end
2 changes: 2 additions & 0 deletions +PropulsionPkg/Contents.m
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Expand Up @@ -4,6 +4,7 @@
%
% Functions
% -------------------------------------------------------------------------
% CheckEdgePowerConsistency - PropulsionPkg.CheckEdgePowerConsistency is a function.
% CreatePropArch - PropulsionPkg.CreatePropArch is a function.
% EngineLapse - PropulsionPkg.EngineLapse is a function.
% EvalSplit - PropulsionPkg.EvalSplit is a function.
Expand All @@ -16,5 +17,6 @@
% PropulsionSizing - PropulsionPkg.PropulsionSizing is a function.
% RecomputeSplits - PropulsionPkg.RecomputeSplits is a function.
% TestCreatePropArch - PropulsionPkg.TestCreatePropArch is a function.
% TestEdgePowerConsistency - PropulsionPkg.TestEdgePowerConsistency is a function.
% TestEngineMotorRegressions - PropulsionPkg.TestEngineMotorRegressions is a function.
% TestPowerAvailable - PropulsionPkg.TestPowerAvailable is a function.
21 changes: 20 additions & 1 deletion +PropulsionPkg/PropAnalysis.m
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Expand Up @@ -2,7 +2,7 @@
%
% [Aircraft] = PropAnalysis(Aircraft)
% written by Paul Mokotoff, prmoko@umich.edu
% last updated: 10 mar 2026
% last updated: 16 sep 2026
%
% Analyze the propulsion system for a given set of flight conditions.
% Remember how the propulsion system performs in the mission history.
Expand Down Expand Up @@ -47,9 +47,15 @@
% get the downstream operational matrix
OperDwn = Aircraft.Specs.Propulsion.PropArch.OperDwn;

% get the upstream operational matrix for edge-flow consistency
OperUps = Aircraft.Specs.Propulsion.PropArch.OperUps;

% get the downstream efficiency matrix
EtaDwn = Aircraft.Specs.Propulsion.PropArch.EtaDwn;

% get the upstream efficiency matrix
EtaUps = Aircraft.Specs.Propulsion.PropArch.EtaUps;

% get which propellers are connected to the gas turbine engines
WhichProp = Aircraft.Specs.Propulsion.PropArch.WhichProp;

Expand Down Expand Up @@ -118,10 +124,23 @@

% get the necessary splits
LamDwn = Aircraft.Mission.History.SI.Power.LamDwn(SegBeg:SegEnd, :);
LamUps = Aircraft.Mission.History.SI.Power.LamUps(SegBeg:SegEnd, :);

% check for a windmilling engine
Windmill = Aircraft.Mission.History.SI.Power.Windmill(SegBeg:SegEnd, :);

% The two operational matrices describe the same mission point. Reject
% edge flows that disagree even when both matrix row sums are valid.
for ipnt = 1:length(PreqSnk)
SplitUps = PropulsionPkg.EvalSplit(OperUps, LamUps(ipnt, :));
SplitDwn = PropulsionPkg.EvalSplit(OperDwn, LamDwn(ipnt, :));
if (any(Windmill(ipnt, :)))
SplitDwn = RedistForWindmill(SplitDwn, Windmill(ipnt, :), nsrc, ncomp);
end
PropulsionPkg.CheckEdgePowerConsistency( ...
Arch, SplitUps, SplitDwn, EtaUps, EtaDwn, PreqSnk(ipnt));
end

% aircraft weight
Mass = Aircraft.Mission.History.SI.Weight.CurWeight(SegBeg:SegEnd);

Expand Down
8 changes: 5 additions & 3 deletions +PropulsionPkg/PropArchConnections.m
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Expand Up @@ -2,7 +2,7 @@
%
% [Aircraft] = PropArchConnections(Aircraft)
% written by Paul Mokotoff, prmoko@umich.edu
% last updated: 17 jan 2025
% last updated: 16 sep 2026
%
% Given a propulsion architecture, identify any parallel electric motor /
% engine connections. These connections are used to reduce the power
Expand Down Expand Up @@ -77,7 +77,9 @@
if (~isempty(Driving) && ~isempty(Helping))

% list the electric motors
ParConns{Driving} = [ParConns{Driving}; Helping];
for idrive = Driving(:)'
ParConns{idrive} = [ParConns{idrive}; Helping];
end

end
end
Expand All @@ -86,4 +88,4 @@
Aircraft.Specs.Propulsion.PropArch.ParConns = ParConns;


end
end
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