# I to design this turbine blade

• T C
In summary: I don't know the name of those wings. But I know that they produce the maximum lift in comparison to other kind of wings. They also produce maximum drag that limits the velocity of the plane.
T C
TL;DR Summary
I need help from others here regarding designing a turbine blade.
Given above is a rough model of what I want to make. This is in fact a turbine that will be placed in airlfow of 65-70 m/s velocity. I want to make it by using a 3D printer. But I want to use the best design of the blades that will give me highest output out of this airflow. Can anybody tell me how to design blades (like as shown in the photo) so that the design can be fed to a 3D printer. The gap between two rings for my design is 3 cm and the width of the turbine would be 4 cm.

T C said:
The gap between two rings for my design is 3 cm and the width of the turbine would be 4 cm.
Is that 4 cm width or depth? Is it the chord length of the blades 4 cm?

It looks like you will need to make 9 separate blades. Those will be mounted between the two steel ducts. Or will you fabricate the entire spinner as a single unit?

Each blade will be a 3 cm wide section of airfoil with a chord length of 4 cm. Because the blades are short they will have very little twist.

I just want to make/print the blades and put those in the still frame later. And this is a comparatively shorter model. The model I want to make has 19 cm external and 16 cm internal radius.

T C said:
But I want to use the best design of the blades that will give me highest output out of this airflow. Can anybody tell me how to design blades (like as shown in the photo) so that the design can be fed to a 3D printer.
Wow. That is a particularly difficult problem in computational fluid dynamics. Maybe someone can recommend a book, or a public domain software package. Be prepared to spend lots of time and effort to compute the answer.

The blade has an airfoil profile that is determined by inner and outer radii. You need to fix the ratio of those radii, or redesign from scratch. You also need to fix the length of the airfoil chord. You will also need to specify turbine RPM when airflow is 65-70 m/s velocity.

Is this a turbine that rotates, or a stator in a duct? There will need to be a dome on the upstream side and a cone downstream, to keep the flow clean. The turbine does not exist in isolation.

Lnewqban and russ_watters
Baluncore said:
Is this a turbine that rotates, or a stator in a duct? There will need to be a dome on the upstream side and a cone downstream, to keep the flow clean. The turbine does not exist in isolation.
This is not a stator but rather a turbine. I have mentioned it at the start. Can't understand why a dome and cone is needed to keep the flow clean.

anorlunda said:
Wow. That is a particularly difficult problem in computational fluid dynamics.
I hope there is an optimum design and data for a model airplane wing, with similar scale, profile and airspeed.

T C said:
Can't understand why a dome and cone is needed to keep the flow clean.
Look at the compressor at the front of a jet engine. There is a dome that keeps the flow entering the compressor clean. The blades will work efficiently only if there is laminar flow over the blade airfoil.

anorlunda
Just consider that the flow is laminar without a dome. I mean there are ways to make a laminar flow (that I don't want to discuss here) without a dome. I am only concerned here about the design of the blades and not in any other factor.

Just found this design from the link. But not sure whether any 3d printing company can make what I want to from this design or not. Kindly help!

This didn't get a response, so I'll bump it and expand:
Baluncore said:
You will also need to specify turbine RPM when airflow is 65-70 m/s velocity.
If you want higher rpm you get lower torque and vice versa. This should be optimized for what is being driven.

T C said:
View attachment 263002
Just found this design from the link. But not sure whether any 3d printing company can make what I want to from this design or not. Kindly help!
You could probably send that to someone and just say you want that shape 3cm long and extruded 3cm high and get something you can use.

To whom? I don't know such an expert for now.

Can anybody here at least what this type of wings are named as? Such kind of wings were used in early aircrafts when the velocity of planes are low. Such kind of wings produce the maximum lift in comparison to othe kind of wings. But it also produces maximum drag that limits the velocity of the plane.

T C said:
To whom? I don't know such an expert for now.
Google turns up lots of hits for on demand 3d printing. Research, pick one and talk to them.

I have already searched it. But 3D printers require further details. Like the frontal angles, tip angle, curveture radius etc.

T C said:
I have already searched it. But 3D printers require further details. Like the frontal angles, tip angle, curveture radius etc.
Most probably just want a CAD file. Do you have access to CAD software (there are free/open source ones...)? Get it, draw what you want them to make, and send it to them.

Honestly, I don't see/understand the problem here. People do this kind of thing all the time.

They are called buckets, or vanes, not wings.

@Baluncore came closest to what you need. It is analogous to the turbine section of a jet engine.

If you search around online, or perhaps in junkyards, you might find an affordable vane to buy and copy. You might also find a drawing showing the cross section.

But how close this will come to "best design" for your application is guesswork without the detailed calculation. Designs like that don't scale well in size or air velocity. It is up to you decide how confident you need to be that what you have is "best."

Even the number of vanes is not guaranteed to be best. Your picture shows 9.

berkeman
russ_watters said:
Honestly, I don't see/understand the problem here. People do this kind of thing all the time.
i just want to know a few little things. The necessary data so that I can make it from a 3D printer and the name of this type of wings. Nothing else!

anorlunda said:
But how close this will come to "best design" for your application is guesswork without the detailed calculation. Designs like that don't scale well in size or air velocity. It is up to you decide how confident you need to be that what you have is "best."

Even the number of vanes is not guaranteed to be best. Your picture shows 9.
This is the sort of thing one might do a master's thesis on. It isn't easy or quick (I know you are just pointing out the variables...). My advice for the OP is to start by just making *something* that works, as a starting point. Right now the path seems likely to yield nothing but analysis-paralysis, but if he just *does it*, he'll at least end up with a functional turbine. If he sets that criteria as a goal, it's pretty much impossible to fail.

berkeman and anorlunda
A very common airfoil is still the Clark Y. Just draw something that looks like that and it will work.
https://en.wikipedia.org/wiki/Clark_Y_airfoil

The problem with 3D printing an airfoil will always be thinning the trailing edge.

T C said:
Just found this design from the link. But not sure whether any 3d printing company can make what I want to from this design or not. Kindly help!
Those thick high-camber airfoils had the highest lift, but also had very high drag. They were the German style from Gottingen University 100 years ago. The thickness gave more rigidity for early monoplane wings, but greatly reduced the maximum airspeed.

Lnewqban, Klystron and russ_watters
I have chosen one. Kindly see the attached file. It's a high camber more lift type of wing used long ago in low speed aircrafts. Whatsoever, I need just one more help. I can't understand the table 177 given in the attached file. Need help to understand it.

#### Attachments

• The wing.pdf
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T C said:
I have chosen one. Kindly see the attached file. It's a high camber more lift type of wing used long ago in low speed aircrafts. Whatsoever, I need just one more help. I can't understand the table 177 given in the attached file. Need help to understand it.
Do you understand any of it? Those are just geometric properties picked-off of/interpreted from figure 137.

Some, not all. Especially those at the top i.e. Maximum Thickness and Maximum Camber part. Rest is more or less clear.

T C said:
Some, not all. Especially those at the top i.e. Maximum Thickness and Maximum Camber part. Rest is more or less clear.
They are expressed in % of chord and you can read them straight off the graph: 5.9% is 0.059 on the graph. And the X-coordinate is given at 0.21. In other words, if the chord length is 100 cm, the maximum thickness is 5.9 cm.

Is this going to be placed inside a duct, or is it going to be in free airflow? Basically, is the flow constrained to go through the turbine, or can it also flow around it? That will significantly change the design considerations here.

cjl said:
Is this going to be placed inside a duct, or is it going to be in free airflow? Basically, is the flow constrained to go through the turbine, or can it also flow around it? That will significantly change the design considerations here.
This will be placed inside a duct. And, by the way, can anybody tell me the "critical angle of attack" and the lift to drag ratio for that speicific angle for such a wing type?

What would be the Reynold's number if it's simple air at 1 barA pressure and at arouind normal temperature?

A good search term is Reynolds number. Two good hits are:

For a general overview: https://en.wikipedia.org/wiki/Reynolds_number
For an airfoil: http://airfoiltools.com/calculator/reynoldsnumber

Note that you will have one Reynolds number for the flow through the duct, and a different Reynolds number for one of the fan blades. Which is why it's a good idea to carefully read through a general overview of the Reynolds number before jumping to a specific calculation.

OK. What are the flow conditions in the duct? Is there a significant pressure ratio from the inlet to the outlet? What kind of flow velocity are you expecting?

jrmichler
T C said:
Summary:: I need help from others here regarding designing a turbine blade.

Given above is a rough model of what I want to make. This is in fact a turbine that will be placed in airlfow of 65-70 m/s velocity. I want to make it by using a 3D printer. But I want to use the best design of the blades that will give me highest output out of this airflow. Can anybody tell me how to design blades (like as shown in the photo) so that the design can be fed to a 3D printer. The gap between two rings for my design is 3 cm and the width of the turbine would be 4 cm.
Blades are 35.5° relative to the incoming wind, I assume?

enkii57 said:
Blades are 35.5° relative to the incoming wind, I assume?
For this model maybe, but that's not exactly what I want to made. The blade angle is different for my case.
cjl said:
OK. What are the flow conditions in the duct? Is there a significant pressure ratio from the inlet to the outlet? What kind of flow velocity are you expecting?
The velocity is around 66.5 m/s.

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