Hi,everyone.

Now i'm optimizing a centrifugal compressor whose blade with both leading and trailing blunt edge. When i procees Autoblade_Fitting, the software prompts me that "no intersection between target suction side and a stream surface". I know that there are no commom points at the leading and trailing edge. How can i write the geomturbo file? I want to fit the blade profile with both leading and trailing blunt edge.

Who know the geomturbo file format? Any help will be welcome.

Now the format of my geomTurbo file is as follows:

GEOMETRY TURBO VERSION 3.7

geometric_tolerance 1e-006

blade_expansion_factor_hub 0.03

blade_expansion_factor_shroud 0.03

blade_merging 0

units 1

number_of_blades 11

data_reduction 0

data_reduction_spacing_tolerance 0.0001

data_reduction_angle_tolerance 90

hub

ZR

31

-0.02 0.02687

......

shroud

ZR

31

-0.02 0.10304

......

suction

SECTIONAL

2

# section 1

XYZ

23

0.0273 0.01244 0

......

# section 2

XYZ

23

0.09234 0.04563 0

......

pressure

SECTIONAL

2

# section 1

XYZ

23

0.02628 0.01448 0

......

# section 2

XYZ

23

0.09157 0.04715 0

......

AutoBlade works with the intersection of the 3D blade surface with the surfaces of revolution defined by the flow paths (stream surfaces). The warning you have indicates that for one or several of the flow paths you do not have an intersection. Extending the 3D blade definition or redefining the flow paths can solve this.

[majid2792]

i have this problem with autoblade too, can you solve it? if you find the problem please help me immidiatly?

[Hamidzoka]

you need to increase the following parameters in your ".geomturbo" file until the airfoil fully intersects with hub and shroud curves:

blade_expansion_factor_hub
blade_expansion_factor_shroud


current values seem to be 0.03. Try bigger values.

Regards

[majid2792]

thank you hamid for your answer
but I dont found exactly what i do
increase my flow path?
or increase my section in geom turbo?

[Hamidzoka]

Dear Majid;
you can increase the span of blades manually through the ".geomturo" file.
if you pay a look at the geomturbo file presented by Stewart, both "blade_expansion_factor_hub" and "blade_expansion_factor_shroud" parameters are set to 0.03. it means that the generated blade should extend from both sides to 0.03m. So, you can easily change these parameters until they intersect with hub and shroud curves.
another way to do this is to extend the blade height directly from Autogrid.
depending on your Autogrid version (i.e. 4 or 5) the method is slightly different.

[majid2792]

Dear hamid
I do it but I have this problem too, Do you have another suggestion؟
best regard

[majid2792]

My error is:
''No intersection between target suction side and a stream surface.''
computation of the intersection between the target blade and the stream surfaces of the parametric geometry.

[Hamidzoka]

try "exchange suction and pressure" prior fitting process.

[majid2792]

I try but i have problem too
Dear hamid, what file can be set in import target geometry file?
the geomturbo file?

[Hamidzoka]

Yes, the tagret file is the "geomturbo" file. would you send me your file?

[majid2792]

ok
can you give me youre email?

[Hamidzoka]

hamid.zoka@gmail.com

[Hamidzoka]

Majid;
You need to study Numeca manuals carefully!
I 've reviewed your ".geomturbo" file and following tips come to my mind:

-you have assigned suction curves to pressure side and vice versa. you should fix it. simply change the suction curves with the pressure ones.

-when you work with Numeca you had better to use SI units. your dimensions(i.e. XYZ and ZR points) are all in mm and this causes problem. if you simply set the scaling factor in Autoblade fitting medium to 0.001 the so called error disapears. you had better to set "data reduction" to 1.
but you may still see this error: "initialization failed" or something like that. to solve this problem I suggest you the following tip:

-before parametrizing your geometry in Autoblade fitting (Design 3D), you need to check if parametrization settings fitts to your blade. for example number of suction and pressure Bsplines control points and their stretching factor should be properly selected. Also the LE and TE parameters (Round or Blunt) and... . if not, you will have a blade with intersecting suction and pressure sides that is clearly useless.
this needs try and error and more substantial works!

One more question: What is the name of your professor?

Regards

[majid2792]

Thanks dear hamid
I try to solve it
Dr derakhshan

Originally Posted by Hamidzoka

Majid;
You need to study Numeca manuals carefully!
I 've reviewed your ".geomturbo" file and following tips come to my mind:

-you have assigned suction curves to pressure side and vice versa. you should fix it. simply change the suction curves with the pressure ones.

-when you work with Numeca you had better to use SI units. your dimensions(i.e. XYZ and ZR points) are all in mm and this causes problem. if you simply set the scaling factor in Autoblade fitting medium to 0.001 the so called error disapears. you had better to set "data reduction" to 1.
but you may still see this error: "initialization failed" or something like that. to solve this problem I suggest you the following tip:

-before parametrizing your geometry in Autoblade fitting (Design 3D), you need to check if parametrization settings fitts to your blade. for example number of suction and pressure Bsplines control points and their stretching factor should be properly selected. Also the LE and TE parameters (Round or Blunt) and... . if not, you will have a blade with intersecting suction and pressure sides that is clearly useless.
this needs try and error and more substantial works!

One more question: What is the name of your professor?

Regards