Rotating Detonation Engine (RDE) -- Dynamics and Bifurcations

Here's a video that presents the science behind rotating detonation engines; the article was pretty light on detail. This video is at the other end of the spectrum, clearly intended for other researchers in this domain. Or, if it's over your head (it was for me, at least while trying to wake up), you can still enjoy the pretty damn cool high speed imaging of the detonation waves in this type of engine. ▶ this video

in “Japan tests explosion-powered rocket for the first time in space (2021)” · View on HN

I think a better title would be "Hall Thrusters Understood So Well Better Instruments Needed to Measure the Friction of Quanta" - If something has momentum, it has mass. - If something isn't leaving an engine now, it's condensing. - Electromagnetic fields can recruit and organize a conductors' permissively and permeability. Hall Thrusters use electromagnetic confinement. - If there is a delay in exhaust, there is condensation. If there is condensation without a holding tank then there is a pulse holding the condensation. - Pulse waves require detonating fuel at the right time to feed the pulse and never feed the lull. Also, detonating is... different. Careful control of timing is needed to maintain a pulse. Finer detection is needed for tuning the pulse. It will take work to understand where this tiny detonating mass has friction in its electromagnetic confinement. - Hall Thrusters once understand more can possible be tuned to run with, dipole, quadrupole... tuned pulse waves. A Hall Thruster is a "smaller" version of this ▶ this video however, the fluid dynamics of the Hall Thruster have interactions at the Quanta maybe so those will be that hardest to detect and analyze. But, once recorded and analyzed the knowledge should help fine tune these engines. Let me link this again because it is just a great presentation on the fluid dynamics behind these effects ▶ this video

in “No one knows why the most used spacecraft propulsion system works” · View on HN

Would an toroidal aerospike work with rotary detonation? :-) What sort of nozzles can one use with an RDE? I see that one can have multiple rotating pulses in an RDE [1]; I guess with some work the engine designer can control the number of pulses, is that right? Are there performance tradeoffs when deciding how many pulses to employ? What are they? If employing multiple pulses, does one want them rotating the same direction, or opposite directions? BTW, Scott Manley has an introductory video about RDEs [2]. [1] 5:50 in ▶ this video [2] [link]

in “Japan tests a rotary detonation engine in space, big increase in fuel efficiency” · View on HN