Design of impeller blades of an axial pump

[A_B_T]

Hi,
Does anybody have any great books or references on the design of the blades of an axial pump, and their profile?
So far I've only been able to find books and articles mentioning that the blades are airfoil formed, but I haven't found any rule of thumb or handbook on the actual profile selection.
Hope my question makes sense, and thanks in advance!

 

[ashtree]

I don't have any references but have a look at boat propeller design. I am pretty certain that a long time ago i saw where a large ship had a Clark Y airfoil for the propeller. I have no idea whether it said that this was good or bad however.
Given that an axial flow pump impeller is likely to be relatively small in diameter(lets say a couple meters at the most even in a large unit) then it would be unlikely that a single airfoil would be appropriate due to the change in chord, pitch and linear velocity over the length of the blade.
The "aerodynamics" of a propeller in an axial flow pump is obviously heavily impacted by the viscosity of the fluid and as such the best such airfoil section would be very different to a aircraft propeller or wing.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[Artisi]

Are you trying to reinvent the wheel, or a bit more detail on what the aim is might be helpful.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[A_B_T]

Thank you ashtree and Artisi!
It's for a very small blood pump, about 25mm in diameter. And we estimate about 4000-6000 rpm, so the Reynolds number along the length of the blades are both laminar, turbulent and transitional. The current pumps(LVAD's) have what seems to be a well thought out design, in order to avoid blood damage.
e.g.

That's not the aim of the project at this point though. We want to see if it's possible with a more typical design. We've been looking at NACA 4-series profiles so far, since we can easily get the lift and drag coeffecients for these profiles using XFOIL. And then just using simple 2d velocity diagram to decide the angles. Though I've been reading that due to our hub/tip ratio, we need to look into 3d flow over the blades.

Thanks

 

[EdStainless]

For some small pumps where fluid damage is a risk you will see impellers with very large hubs, the result of this is that there is less difference in flow regime across the blades.
Yes, the profile varies greatly with radial position.

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P.E. Metallurgy, Plymouth Tube

 

[Artisi]

The design as such is beyond my scope of expertise but would be interested in knowing flow and head required and why such high speed?
A few life times back I worked for a manufacturer who designed and manufactured axial flow pumps (true airfoil) with impeller diameters of 4" to 24"- 4,5,6,8,blades depending on pump size and blade tilt, we also had a scale model unit with impeller diameter something below 1", the flowrate was unbelievable for its size, as to the developed I have no idea but would think it only a couple of feet at best.
Rather than such high speed, multi stage might be a better option.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Strong]

Lots of information if you search/Bing/Google for "mixed flow pump design"
Perhaps you don't want a mixed flow design.

Walt

 

[A_B_T]

Thanks again,
We estimate a flow rate of about 6 L/min, and a head of about 30 mmHg. I'll have to look into multistage, though I think size will be a problem. The Mixed flow pumps look interesting!

 

[Artisi]

For 6L/min at 30mm Hg a 1"axial flow at 4/6000 rpm sounds farcical.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)