From 1433455ac0f3b0b7e769a56ff260a67a5f2bc2f2 Mon Sep 17 00:00:00 2001
From: lr360 <liz_tp@proton.me>
Date: Thu, 27 Jul 2023 13:35:09 +0200
Subject: [PATCH] fix: set true calculation of reynolds number
calculate reynolds number exact value in indvel.m
use its exact value when possible, if not use an approximation in ElemPerf.m
---
src/classes/@ElemPerf/ElemPerf.m | 24 +++++++++++++++++++-----
src/solvers/indvel.m | 7 +++++--
2 files changed, 24 insertions(+), 7 deletions(-)
diff --git a/src/classes/@ElemPerf/ElemPerf.m b/src/classes/@ElemPerf/ElemPerf.m
index 78b33cf..8f883c8 100644
--- a/src/classes/@ElemPerf/ElemPerf.m
+++ b/src/classes/@ElemPerf/ElemPerf.m
@@ -56,7 +56,6 @@ classdef ElemPerf < handle
Rot (1, 1) Rotor % Handle of the rotor linked to this specific ElemPerf instance
Op (1, 1) Oper % Handle of the Operating point linked to this specific ElemPerf instance
- reynolds (1, :) double % Reynolds number, [-]
upstreamVelAx (1, :) double % Upstream axial velocity above rotor disk, [m/s]
upstreamVelTg (1, :) double % Upstream tangential velocity above rotor disk, [m/s]
@@ -85,6 +84,7 @@ classdef ElemPerf < handle
% from a single set method otherwise.
properties (Dependent)
alpha (1, :) double % Angle of attack, [rad]
+ reynolds (1, :) double % Reynolds number, [-]
indVelAx (1, :) double % Induced axial velocity at rotor disk, [m/s]
indVelTg (1, :) double % Induced tangential velocity at rotor disk, [m/s]
inflowRat (1, :) double % Inflow ratio, [-]
@@ -96,6 +96,7 @@ classdef ElemPerf < handle
% Cache for dependent properties to avoid excessive recalculation
properties (Access = private, Hidden)
alpha_ (1, :) double % Angle of attack, [rad]
+ reynolds_ (1, :) double % Reynolds number, [-]
indVelAx_ (1, :) double % Induced axial velocity at rotor disk, [m/s]
indVelTg_ (1, :) double % Induced tangential velocity at rotor disk, [m/s]
inflowRat_ (1, :) double % Inflow ratio, [-]
@@ -128,10 +129,6 @@ classdef ElemPerf < handle
% In-plane velocities
self.tgSpeed = Op.omega .* Rot.Bl.y;
- % Reynolds
- relVel = sqrt(self.tgSpeed.^2 + Op.speed.^2);
- self.reynolds = Flow.reynolds(relVel, Rot.Bl.chord, Op.Flow.mu, Op.Flow.rho);
-
% Get alpha_0 from reynolds
self.alpha0 = zeros(size(self.pitch));
for i = 1:length(Rot.Af)
@@ -162,6 +159,18 @@ classdef ElemPerf < handle
alpha = self.alpha_;
end
+ function reynolds = get.reynolds(self)
+ % if true reynolds is unknown, we use an approximated value
+ % with the upstream velocity instead of relative velocity at
+ % the rotor disk
+ if isempty(self.reynolds_)
+ relVel = sqrt(self.tgSpeed.^2 + self.upstreamVelAx.^2);
+ reynolds = Flow.reynolds(relVel, Rot.Bl.chord, Op.Flow.mu, Op.Flow.rho);
+ else
+ reynolds = self.reynolds_;
+ end
+ end
+
function indVelAx = get.indVelAx(self)
indVelAx = self.indVelAx_;
end
@@ -197,6 +206,11 @@ classdef ElemPerf < handle
[self.cl, self.cd] = getclcd(self, val);
end
+ function set.reynolds(self, val)
+ % Cache value
+ self.reynolds_ = val;
+ end
+
function set.indVelAx(self, val)
% Cache value
self.indVelAx_ = val;
diff --git a/src/solvers/indvel.m b/src/solvers/indvel.m
index 0a340c2..48d7c8a 100644
--- a/src/solvers/indvel.m
+++ b/src/solvers/indvel.m
@@ -68,15 +68,17 @@ function indvel(OpRot, Mod)
% Local mass flow rate
dmdot = 2 * pi * OpRot.Op.Flow.rho * OpRot.Rot.Bl.y * OpRot.Rot.Bl.dy .* v;
- % Compute new estimates for the velocity magnitude and flow angle
+ % Compute new estimates for the velocity magnitude and Reynolds
+ % number
relVel = sqrt(v.^2 + u.^2);
+ reynolds = Flow.reynolds(relVel, OpRot.Rot.Bl.chord, OpRot.Op.Flow.mu, OpRot.Op.Flow.rho);
% Angles
phi = atan2(v, u); % Inflow angle
alpha = OpRot.ElPerf.truePitch - phi;
% Get new estimates for the coefficients
- [cl, cd] = OpRot.ElPerf.getclcd(alpha);
+ [cl, cd] = OpRot.ElPerf.getclcd(alpha,reynolds);
% Loss factor (separate swirl and axial components)
lossFact = prandtlloss(OpRot.Rot.nBlades, OpRot.Rot.Bl.r, OpRot.Rot.r0, phi, ...
@@ -118,6 +120,7 @@ function indvel(OpRot, Mod)
OpRot.ElPerf.alpha = alpha;
OpRot.ElPerf.indVelAx = v - OpRot.ElPerf.upstreamVelAx;
OpRot.ElPerf.indVelTg = uw / 2;
+ OpRot.ElPerf.reynolds = reynolds;
end
--
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