Abstract
The Ariane 5 failure flight 157 made clear that the loads in the base region of space launcher configurations were underestimated and its near-wake dynamics required more attention. In the recent years, many studies have been published on buffet/buffeting in the critical high subsonic flow regime. Nevertheless, not much experimental data are available on the interaction of the ambient flow with an exhaust jet over a wide subsonic Mach number range. Further, a preceding study without exhaust jet revealed questions regarding a similar distribution of the velocity and Reynolds stress in the near-wake if scaled with the reattachment length. Consequently, a generic space launcher configuration featuring a cold, supersonic, over-expanded jet is investigated experimentally in the vertical test section Cologne (VMK) by means of particle image velocimetry (PIV) for five subsonic Mach numbers ranging from 0.5 to 0.9 with corresponding Reynolds numbers between Re_{text {D}}=0.8times 10^6 to 1.6times 10^6. The velocity and Reynolds stress distribution are provided for the near-wake flow and additionally for the incoming boundary layer. Just as in the preceding study, self-similar features are found in the flow field as long as the separated shear layer reattaches on the solid nozzle wall. Substantial changes are then measured for an alternating (hybrid) reattachment between the solid nozzle wall and supersonic exhaust jet as found for Mach 0.8, one of them being the increased axial turbulence in the recirculation bubble due to a ‘dancing’ large-scale, clockwise-rotating vortex.Graphic abstract
Highlights
The inquiry board in charge of the investigation of space transportation system Ariane 5 flight 157 in 2002 came to the conclusion that one of the most probable reasons for the failure was a ‘non-exhaustive definition of the loads to which the Vulcain 2 engine is subjected during flight’
The results indicate a coupling between near-wake dynamics and the aeroacoustics of the jet
The objective of the current study was to contribute data for a better understanding of the buffet/buffeting effect as it occurs in the base region of space launcher configurations such as Ariane 5 in the subsonic flow regime
Summary
The inquiry board in charge of the investigation of space transportation system Ariane 5 flight 157 in 2002 came to the conclusion that one of the most probable reasons for the failure was a ‘non-exhaustive definition of the loads to which the Vulcain 2 engine is subjected during flight’. This incident was the driver for a number of base flow investigations with the objective of understanding and quantifying these loads.
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