I’m rather happy with how our testing is progressing over the last several weeks. Jon, Ian, and Pierce are getting this down to an art. More significantly we’re to the point where we can now go out to do a test and learn from the test what we want to learn.
As I mentioned earlier, we got a new engine chamber in to test regenerative cooling. A few days ago we went out to start getting thermal data for cooling the engine. We did a whole bunch of runs, collecting thermal data and extending our run times. The longest run was only 11 seconds, but that is nearly 4 times the length of previous runs. We found two things. First, the injector isn’t quite right yet, as the IPA side pressure drop is too low, the C* efficiency was suffering, and there is definite instability at the ‘ideal’ mixture ratio. Second, this engine should reach thermal equilibrium without destroying the nozzle.
Yesterday, the guys went out and did a really long test. The chamber reached thermal equilibrium about halfway through a 42 second run. The reason for 42 seconds is that around 35 seconds or so our data collection system crashed, so no sense in continuing the test when we weren’t getting data. I am really happy that theory and reality didn’t match up for once, as our initial analysis indicated that cooling was going to be a lot more of a challenge. We were expecting to have to do some combination of film cooling, running rich, and accepting a huge pressure drop in the cooling channels. Now it looks like none of that is necessary.
We are getting new injector parts made up and hope to test those later this week, that should take care of the stability and efficiency issues. After that we will work on the startup and shutdown. As you can see in the video, the startup and shutdown transients are much rougher than is desirable.
8 mb MPEG version