Do you have a simple drawing to post? Time to put our toes in the water, if it's not to hot or cold we can dive in.
John Carmack wrote: > For someone that just burned through a $4000 radiative chamber, I am a > happy camper. > > We tested our fourth generation kerosene injector tonight. There will be > pictures in this weekend's update, but basically it has an even tighter > venturi, down to 0.6" (with a 0.5" throat), and instead of the fuel coming > in as a high velocity jet from the side of the venturi, a stainless pipe > comes in from the outside on the catalyst pack side of the venturi, and it > has a pretty sizable hole in the bottom, before a plugged end. The idea is > to have very low velocity fuel stream straight down the middle of the very > high velocity (nearly sonic) peroxide decomposition, much like an SSME lox > post injector in reverse. > > We put the radiative chamber together with the high temperature bolts, the > stainless clamp ring, and the silica gasket material (not the gas-filled > O-rings, which have yet to arrive). We also wet sanded the silicide coated > flange, and used a torque wrench to evenly tighten the flange to 6 ft-lb on > each of the #10 socket head cap screws. All of the runs sealed absolutely > perfectly. > > We started off very rich (but not as rich as we were running the regen > engine), and immediately on lighting, it was obvious things were working a > lot better, because the engine started glowing much more rapidly, and much > higher up. There was still a visible bias opposite the fuel inlet, > probably because the flow had enough momentum that it was not "turned" > completely axially when it came out of the drilled hole. > > Our oxidizer-only Isp was 246, up from a previous best of 192! We shrank > the fuel jet a good chunk, and the oxidizer-Isp increased a bit more. We > shrank it some more, and it finally nosed over a bit, which would still be > at increasing "true Isp". > > We will have to get our sight glass hooked back up so we can measure the > kerosene flow, but this was with an 0.040" kerosene jet, while a 0.060" jet > resulted in a measured O:F of 2.2:1 on Saturday, so that would put us > around 5:1 O:F, which would be a true Isp of 208! > > We will have to check the load cell calibration and more precisely measure > the kerosene flow, but it was clearly a huge improvement. > > Thrust was 45 lbf +/- 5% at 250 psi feed pressure. > > We have great video of all these tests, including it throwing molten glass > beads off of our cinder block blast deflector. The entire chamber is > glowing like a star, flaring so you can't see the outline in the video. > > We loaded up four liters of peroxide and let it run. The burn was nice and > monotonous, but after 45 seconds of hot fire, the plume started deflecting > slightly, and some sparks started coming off the nozzle. I killed the > kerosene, and let the rest run out as monoprop. > > We burned the silicide coating off at the nozzle, which allowed the TZM to > vaporize a hole. The entire side opposite the fuel fitting has a different > look to the coating, so I am going to send it back to Hitemco to have them > tell us some things about it, and have the second chamber coated. We are > going to resolve the bias towards one side, possibly improve our film > cooling, and stay a bit richer. > > We may be near the theoretical max Isp (220 at a leaner mixture), but we > wanted to get rid of the uneven combustion, so we modified the fuel > injector tube to actually take a 90 degree turn (cut, bend, weld), instead > of having a hole drilled in the side. This will give straighter, and even > lower velocity fuel injection. We won't be able to "see" the difference > until we get the second chamber coated, but we are going to test it with > the regen engine (at a much richer jetting) this weekend. I have a good > ring of film "cooling" steam holes in the injector, but I may make a ring > on the bottom to turn them into a sheet instead of multiple jets. We may > have problems with regen cooling, because the greatly increased efficiency > will have increased the chamber temperature and decreased the peroxide flow. > > We are laying out the work for a 1000lbf regen biprop now. > > John Carmack > > _______________________________________________ > ERPS-list mailing list > [EMAIL PROTECTED] > http://lists.erps.org/mailman/listinfo/erps-list -- >>>>>>>>>>>>>>>>----<<<<<<<<<<<<<<<<< ........ Alex Fraser N3DER ......... ......... [EMAIL PROTECTED] ....... [~]_>^</\-[~]_>^</\-[~]_>^</\-[~]_>^< _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
