Hydralox with Oxygen Thrust-Augmented Nozzle?

[InterestedEngineer]

I seem to recall that much of the thrust gain from augmentation was in reducing the losses from over expansion. One cold flow experiment from years back was a small jet reverse flow into the over expanded nozzle. Kicked the flow over to the side and entrained ambient air into the nozzle to achieve an aerospike like effect in a conventional over expanded nozzle. Noticeable increase in thrust.  All low pressure stuff (<200 psi) with compressed air.

I would love to see the paper on that.

[Robotbeat]

Try NTRS.nasa.gov

[redneck]

I seem to recall that much of the thrust gain from augmentation was in reducing the losses from over expansion. One cold flow experiment from years back was a small jet reverse flow into the over expanded nozzle. Kicked the flow over to the side and entrained ambient air into the nozzle to achieve an aerospike like effect in a conventional over expanded nozzle. Noticeable increase in thrust.  All low pressure stuff (<200 psi) with compressed air.

I would love to see the paper on that.

I never wrote it up. I thought at the time that one of the Mojave companies was going to try my notchbell compensating nozzle.  Later I thought I could get something done when my finances permitted. I had realized by that time that the start ups couldn't afford to take too many chances on an unproven concept from an unproven source (me). The idea was that I would fund the notchbell through proof of concept and then move on to this one.

The rig was a 250 gallon tank pressurized on shop air to almost 200 psi. Blow down through a 1" hose to a nozzle mounted to a scale. No DAQ other than eyeball and memory. 1/2" throat to 1&1/2" exit. When the exterior air 1/8" hit at the right angle, the scale would jump about 5 pounds depending on the current blow down pressure. Lot of fun with sucking threads back into the nozzles when things worked right.

I could recreate it in a few weeks if there were a reason to do so. I don't really expect that to happen.

[VSECOTSPE]

See section 2.6 on “Rocket Augmentation for Turboaccelerator” in paper below.  Dumps an oxidizer in the afterburner of a turbine engine.  Similar to this thread’s concept.

https://www.sto.nato.int/publications/STO%20Educational%20Notes/RTO-EN-AVT-150/EN-AVT-150-02.pdf

[redneck]

See section 2.6 on “Rocket Augmentation for Turboaccelerator” in paper below.  Dumps an oxidizer in the afterburner of a turbine engine.  Similar to this thread’s concept.

https://www.sto.nato.int/publications/STO%20Educational%20Notes/RTO-EN-AVT-150/EN-AVT-150-02.pdf

Thanks for the link. I used to be familiar with several of those concepts with others being new to me. I remember my conclusions and some ideas from then. I may do some posting on my views when time permits. Most of these are too expensive and complex compared to conventional rockets, though there are some possibilities there.

[Ithirahad]

Instead of strap-on oxygen tanks, imagine that you have strap-on potassium tanks (while you're at it, also imagine that the potassium somehow behaves like a fluid).

You don't really have to "imagine" that the potassium behaves like a fluid, you just have to add some sodium. If NaK can be sprayed through a repurposed car fuel injector, you can blow it out the sides of a rocket nozzle just fine.