Fixed preset blade pitch angle

[Satyamshk2]

Hello, I am working on a straight-bladed cross-flow turbine (NACA0015) with a solidity of 0.15. I have the experimental data and am trying to simulate the same in CACTUS. I have the data for different pitch angles and want to simulate the same in the cactus. I am modifying the blade pitch angle by changing the mount point ratio (eta) in the code during geometry creation (the quote). My cactus results are not in agreement at all with the experiment data on all the pitch angles. I could not find a way to give a fixed preset blade pitch angle in the code other than changing the mount point for a VAWT.

"**A forward shift of mount-point from the centre of the chord towards the leading edge corresponds to an effective toe-in pitch

change of β = tan^-1[x/R]**"

where x is the distance between the two shifting points. Could you please tell me the ways I can provide blade pitch angle in the code for a Straight-bladed VAWT?

[Satyamshk2]

@whophil @jcokemurray @kmruehl @petebachant Could you please help me here?

[petebachant]

Hi @Satyamshk2, sorry but I've never done this in CACTUS, so I'm not sure if it's possible in the config.

[Satyamshk2]

Hi @Satyamshk2, sorry but I've never done this in CACTUS, so I'm not sure if it's possible in the config.

Thank you

[whophil]

Hi @Satyamshk2 , I'm not sure I understand your question. How are you building the geometry input file? With the parameters described in section 3.2 of the user guide, you should have the flexibility to build whatever geometry you see fit.

[Satyamshk2]

Hi @Satyamshk2 , I'm not sure I understand your question. How are you building the geometry input file? With the parameters described in section 3.2 of the user guide, you should have the flexibility to build whatever geometry you see fit.

Thanks for your reply. I have the flexibility to build whatever geometry I want through the Matlab files. My question was about a fixed preset blade pitch angle. How do you provide the blade pitch angle in the CACTUS code for a VAWT?

Geometry Creation Code

clear close all %GEOMETRY FOR URV MODEL % Creates test VAWT geometry file

% Add geom creation scripts to path path(path,'E:/Satyam/CACTUS-dev/CreateGeom');

% Params R=1.23031; % Center radius (ft) %H=2.46063 %Height of the turbine %RefAR=H*D/R^2 %Frontal area normalized by R^2 HR=2.46063/1.23031; % Height to radius ratio CRr=0.32; % Root chord to radius eta=.5; % Blade mount point ratio (mount point behind leading edge as a fraction of chord) NBlade=3; NBElem=16; NStrut=6; % number of struts NSElem=16; CRs=CRr; % strut chord to radius TCs=0.15; % strut thickness to chord

% Output filename FN='TestVAWT.geom';

% Plot data? PlotTurbine=1;

% Convert dToR=pi/180;

% Create basic parabolic blade VAWT Type='VAWT'; BShape=0; T=CreateTurbine(NBlade,NBElem,NStrut,NSElem,R,[],[],[],Type,1,CRr,HR,eta,BShape,CRs,TCs);

% Write geom file WriteTurbineGeom(FN,T);

% Plot if desired if PlotTurbine

% Plot animated turbine rotation
XLim=[-4,4];
YLim=[-2,4];
ZLim=[-4,4];

% Plot controls
PlotVec=1;
SFVec=.5;
Trans=.5;

hf=figure(1);
set(hf,'Position',[303   124   956   610]) 
set(gca,'Position',[5.2743e-002  5.1245e-002  8.9979e-001  8.8141e-001])
set(gca,'CameraPosition',[-52.1999   30.4749   62.2119])
set(gca,'CameraUpVector',[1.8643e-001  9.7433e-001 -1.2615e-001])
set(gca,'CameraViewAngle',6.3060e+000)
grid on
set(gcf,'Color','white');
hl=light('Position',[-1,0,0]);
set(gca,'Color','white');
set(gca,'DataAspectRatio',[1,1,1])
set(gca,'XLim',XLim,'YLim',YLim,'ZLim',ZLim)

HIn=[];
PhasePlot=linspace(0,2*pi,150);
for i=1:length(PhasePlot)
   H=PlotTurbineGeom(T,hf,PhasePlot(i),HIn,Trans,PlotVec,SFVec);
   HIn=H;
   pause(.01);
end

end

[whophil]

@Satyamshk2 the CreateGeom scripts provided by CACTUS-tools are offered as a convenient way to build simple geometries, but may not cover the use case you need. If CreateTurbine.m doesn't allow you to do what you need, you will need to modify it, following the guidance of Section 3.2 of the User Guide.

I am not the author of the CreateGeom scripts and it's been a very long time since I looked at any of the CreateGeom .m scripts. I took a brief look and I think you do what you want by adding a call to RotateBlade.m to rotate each blade about the desired pitch axis.

[Satyamshk2]

@whophil Thank you for your suggestion. I will try to modify the geometry this way.

[jcokemurray]

Yes, it looks like the basic VAWT generator in CreateTurbine doesn't do blade twist, but the HAWT generator does. You could follow that example to add blade twist to a VAWT model... Jon

On Fri, Mar 11, 2022, 7:30 AM Satyam Shukla @.***> wrote:

@whophil https://github.com/whophil Thank you for your suggestion. I will try to modify the geometry this way.

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[Satyamshk2]

@jcokemurray Dear I am having some problems validating the CACTUS with VAWT850 Case as per ''Murray, J., and Barone, M., “The Development of CACTUS, a Wind and Marine Turbine Performance Simulation Code,” 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Reston, Virginia: American Institute of Aeronautics and Astronautics, 2011, pp. 1–21.'' could you please tell me, what was the mount point(eta in CACTUS Code) in the VAWT850 turbine case as it is not available online? Thanks and regards