[AR] Re: LOX/kero layout (was Re: Above 65000 ft for free)
- From: Peter Fairbrother <zenadsl6186@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Thu, 6 Sep 2018 20:47:40 +0100
On 04/09/18 08:17, Wyatt Rehder wrote:
Also at 400N I'm not sure a turbopump would be the most efficient
choice. Far as I knew they don't scale down to sizes that small that
well.
They do not, which is why I have been working on exotic materials for
blisks.
However if you don't want RD-170 (or BE-4) numbers something like below
can be done.
With a turbine inlet temperature of only 600C and a tip speed of 275m/s,
the turbine material requirement isn't too ridiculous, and the overall
turbopump efficiency requirement is only 10.0%.
However ... that 10% efficiency is not easily obtained.
Pump specific speeds are about 150-600 (US units) - Barske pumps can
deliver about 15-40% efficiency in that range, if well designed and
built. Turbine efficiencies of about 60% are also attainable, and 80%
plus mechanical linkages are possible.
However you have to match the turbine and the pumps for torque and
speed, which is not easy, an even then - 15% x 60% x 80% = 7.25% = fail.
But do I think it is doable :)
Peter Fairbrother
400N rocket engine v2.0
LOX-rich staged combustion
Pumps:
LOX - 107 g/s @ 1.142 kg/l = 93.7 ml/s
kero - 45 g/s @ 0.78 kg/l = 57.7 ml/s
total = 152 g/s = 151.4 ml/s
O/F = 2.38
output pressure 12 MPa
delivered power LOX 1125W (93.7 ml/s x 12MPa)
delivered power RP1 693W (57.7 ml/s x 12MPa)
delivered power total 1818W
at 100,000 rpm-
LOX head= 1050m 93.7 ml/s specific speed = 166 (= 291 US units)
kero head= 1538m 57.7 ml/s specific speed = 97 (= 163 US units)
at 200,000 rpm-
LOX head= 1050m specific speed = 332 (= 582 US units)
kero head= 1538m specific speed = 194 (= 326 US units)
Preburner:
11.6 MPa -> 6MPa exit
LOX/RP1 O/F 36:1
Ae/At 1.0046
Te 613C, 886K
Ve 573 m/s mach 1.07 26.1 kg/m^3
110 g/s flow rate
Turbine:
Gas stream kinetic power 18.06kW
Pumps delivered power 1818W
Turbopump overall efficiency required 10.0%
20 degree Turbine tip optimum velocity 275 m/s
Main Chamber:
Pc 6MPa Pe 1 atm
LOX/RP1 2.38
Ae/At 9.09
ISP: 295s 321s(vac)
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