While Space X prepares to launch its first tourist space flight, other players in the sector in France and Europe are rather working on new, more robust and greener launchers. Moreover, to improve space propulsion, ONERA remains the key partner of CNES and Ariane Group.
Today, ONERA's emphasis is on simulation
What could be better than computer simulation, conducted alongside experimental tests, to save time and test several parameters at once? In June 2021, as part of the development work on the P120C solid propellant rocket engine, which will soon be used as a booster propellant for the future Ariane 6 launcher and as a propellant powering the first stage of the future Vega C launcher, ESA entrusted ONERA, via CNES, with an independent inspection activity regarding the prediction of instabilities that could occur during propellant combustion.
For this P120C solid rocket motor, designed by Avio and Ariane Group, ONERA's expertise on hydrodynamic and thermoacoustic (due to the distributed combustion of the aluminium present in the propellant) instabilities is recognised.
In fact, ONERA recently developed a new aluminium particle combustion model: the combustion software CEDRE has been improved to estimate instabilities during the second P120C qualification firing test in October 2020. Five operating instances, corresponding to different stages of the motor’s internal ballistics, were simulated.
ONERA modelling showed that instabilities are very sensitive to the size of aluminium particles and alumina residue present in the motor. The ONERA calculation procedure evaluating instabilities linked to the combustion of aluminium in a solid propellant could therefore be validated on an industrial motor.
ONERA carried out, under CNES contract, ZDES (Zonal Detached Eddy Simulation) digital simulations around the PPH prototype of the Ariane 6 launcher, which was also tested experimentally in an ONERA wind tunnel. To take into account the geometric complexity of the prototype, linked to the protuberances of the rear body and the connecting rods, ONERA has successfully implemented the innovative digital strategy - Zonal Immersed Boundary Conditions (ZIBC) - which it developed and designed for Ariane 5
Experimental tests on test benches too...
The ONERA Occitanie centre has space propulsion test benches on the Fauga-Mauzac site. Work on the first stage of the future Ariane 6 launcher is carried out there.
In particular, the pressure and thrust measurements are used to validate future computer simulations.