This slow-motion launch footage of Relativity Space’s Terran 1 rocket highlights several intriguing fluid flow phenomena. Let me walk you through the sequence of events that unfold as the rocket takes to the night skies over Cape Canaveral, FL.

As the nine Aeon 1 engines come to full thrust, excess fuel ignites after coming in contact with the engine exhaust plume. This produces the rising orange flames just left of the rocket during the first few seconds of the video. Note the cascade of ice that occurs in the very first few moments of the launch sequence – the violent acoustics and dynamics of the startup of all 9 Aeon engines rapidly shakes off any ice that accumulated on the airframe of the vehicle.

At the same time, condensed atmospheric moisture descends due to its higher density with respect to the surrounding air. As this condensation descends, it gets entrained by the high-velocity exhaust gases at the bottom of the vehicle. This is the Bernoulli effect in action – an increase in the speed of a fluid occurs simultaneously with a decrease in the static pressure of the surrounding air. This drop in static pressure creates a powerful suction effect, pulling surrounding condensation and ice chunks into the lower pressure exhaust stream. The quick disconnect also releases from the vehicle here, and ejects cryogenic liquid oxygen into the exhaust stream, further amplifying the entrainment effect.

This entrainment gains prominence as the rocket takes to the skies. Condensation begins turning sharply into the aft end of the rocket in the short moments following hold-down release.

The exhaust plume of the rocket then unveils as the rocket leaves the pad, exposing bright blue Mach diamonds as the surrounding atmosphere compresses the blue methane-oxygen exhaust stream.

Look at that beautiful blue fire! Notice that some of the exhaust turns a reddish-orange as it interacts with surrounding water and steam.

More ice chunks can then be seen falling directly into the flame, immediately disintegrating into bright white flashes as they are consumed by the plume.

The rest of the trailing exhaust stream then develops into fully turbulent flow as the internal forces of the hot gases overcome viscous forces within the flames.

This event displays the beauty behind the carefully choreographed chaos that is a rocket launch event – condensation descending, ice falling, flames rising, and jets of superheated exhaust gases coming to view as the rocket takes life.

VIDEO CREDIT: Relativity Space / Michael Baylor

Baylor, M. (2023, March). Relativity Launches Terran 1, World’s First 3D Printed Rocket [25% Speed] [May 2022]. Michael Baylor.

Sources:

Ur Rahman, F. (2021). Laminar Flow and Turbulent Flow. The Constructor. https://theconstructor.org/fluid-mechanics/laminar-turbulent-flow/559432/. Accessed 7 Sept 2023.

Bernoulli’s equation Princeton University. Available at: https://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html (Accessed: 07 September 2023).