Would a piston pump reduce or eliminate the problem of cavitation one can
get with a turbine? If yes, this would lead to lower tank pressure, lighter
weight tanks - buys back some of the weight increase of the piston vs
turbopump??
Cheers
Brian Feeney
On Dec 15, 2016 2:40 PM, "Henry Vanderbilt" <hvanderbilt@xxxxxxxxxxxxxx>
wrote:
On 12/15/2016 9:15 AM, Dave McMillan wrote:
XCOR's pumps are not pistonless; that's Flometrics you're thinking of.
On 12/15/2016 11:01 AM, Thomas McNeill wrote:
I have been curious about different pumping mechanisms. Instead of a
turbo pump what about positive displacement pumps, like gear or lobe?
Has there been any attempt at using one of these types of pumps?
I have to admit to being curious why I've never heard of any
amateurs trying a variant on XCOR's piston(less) pumps -- those seem
like a much lower bar to get over than any kind of turbomachinery. Some
subtle difficulty I'm not seeing, there?
As for the root question, I see no reason why developing an electric-drive
piston propellant pump should be particularly challenging.
Off the top of my head...
- You need to pay attention to compatible piston-seal materials (and to
flow-path materials compatibility in general, of course).
- For cryos, you need to pay attention to thermal dimensional issues,
seal & lube temperatures, and flow-path conditioning.
- You need to pay attention to output pressure variations, to the extent
your motor/application may be sensitive to them.
None of those involve bleeding-edge new tech development. Just a matter
of known detail engineering. And there's this: There's a HUGE existing
parts-base out there for piston machinery components, both in pumps for
other applications (pressure-washers anyone?) and in the small IC engine
field.
I'd lean toward the explanation that people haven't looked at piston over
turbine pumps more out of established habit than for fundamental practical
reasons.
After all, if you're using a turbine for pump power, making the pump a
turbine wheel on the same shaft uses design/manufacturing resources you'll
need regardless.
Going to electric pump power, that no longer holds true. You can now skip
the (apparently) considerable investment in high-performance turbine
design/fab capabilities.
Henry
