The machining on any of these small impellers is pretty easy, until it requires
swarf milling on our 5-axis machine they are all about the same. I turn the
profile, cut around the vanes then part, pretty straight forward. I do have
to use a fairly small endmill so the machining time is a bit longer than you
would expect for such a small part, but not horrible. (I should say easy for
our lathe since I can do it all in one setup and if I need to machine on the
back side transfer to the sub-spindle is simple)
These small impellers are all inefficient ~65% would be good, pretty much what
a Barske will do and you don't have to worry about undue regenerative heating
or possibly the stall point of the partial extraction curve. Tip/face
clearance is the biggest difference if you ask me.
Russ Blink
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Peter Fairbrother
Sent: Tuesday, July 14, 2015 12:25 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Arocket Pump Progress
On 14/07/15 16:37, Monroe L. King Jr. wrote:
I agree and it was the Merlin I was looking to for inspiration.
But the split design of the SA-2 also has it's merit and it is
possible to actually get a hold of one of those to get a good look at
and take measurements from as well as perhaps some 3D scans if nothing
else. It can also be copied.
I'm willing to cut some corners here and take advantage of a known
good design if we can.
The other thing is the SA-2's propellants and pump designs are closer
to the same for our chosen propellants.
also looks to me like the SA-2 has open impellers?
If I can find/buy one to use as a reference it should cut development
in half.
Or do you think that is mot a good way to proceed?
This is our project you tell me. You are designing a turbopump Peter.
-------- Original Message --------
Subject: [AR] Re: Arocket Pump Progress
From: Peter Fairbrother <zenadsl6186@xxxxxxxxx>
Date: Tue, July 14, 2015 8:10 am
To: arocket@xxxxxxxxxxxxx
On 14/07/15 14:36, Monroe L. King Jr. wrote:
That does help some! Thank you. I do believe working from this design is
better than trying to go with a V-2 design :)
It's not bad, but if I was designing a turbopump I'd use the Merlin
engine turbopump as an example. It's a pretty good one.
http://www.barber-nichols.com/sites/default/files/wysiwyg/images/merlin_turbopump.jpg
The picture is pretty small, but it shows most things: at the bottom,
from left to right, there is the LOX pump with integral inducer, the
shaft with fuel pump and inducer, the turbine wheel.
It is a reaction turbine, and I think a partial admission one - a
reaction turbine has less end thrust than an impulse turbine, and in
theory only a very low pressure differential across the disk - with a
single shaft with two pumps, both with screw inducers, pumping in
opposite directions to balance end thrust.
Note that the turbine gas flows to the left, creating a leftward end
thrust on the shaft, and the LOX flows to the left, creating a rightward
end thrust to balance both the turbine end thrust and the lesser
leftwards thrust of the fuel pump (fuel flows to the right).
For a smaller engine I would consider Barske style partial emission
pumps, or closed impellers; if nothing else, in order to make
construction easier. Perhaps tesla inducers too.
-- Peter Fairbrother