Base pressure oscillations and safety of load launching into orbit

Physical details regarding base pressure low-frequency oscillations between rocket nozzles, their excitation and maintenance, are considered. Amplitude – frequency characteristics of these oscillations, as well as sequence of their type change, are studied. A single nozzle, a two-nozzle unit and a ring nozzle imitating multi-nozzle unit, are investigated in the present study. •Oscillations of supersonic jet flow into duct with abrupt area change are studied;•Jet flow from various single and multiple nozzles are analyzed;•Model of oscillations based on flow rate misbalance is confirmed experimentally;•Shock-wave structure transformation during self-oscillations is analyzed;•Results achieved can be helpful for safety of spacecraft launching.