Plume-Induced Effects on the Near-Wake Region of a Generic Space Launcher Geometry

Kurzfassung

The near-wake flow of a generic space launcher geometry with jet is investigated experimentally in the hypersonic flow regime at Mach 6 and an unit Reynolds number of 16 · 106 by means of unsteady pressure measurements. This corresponds to an altitude of 50 km for an Ariane V-like launcher with an underexpanded nozzle flow. The investigations with a truncated ideal contoured wind tunnel model nozzle designed for Mach number of 2.65 is used to simulate the nozzle flow. The objective of this study is the characterization of the plume-induced loads on the main structural components in the near wake region during flight. A parametric study with the reservoir pressures of 11, 14, 17 and 20 bar is presented. The transducers capture the pressure signal in the radial and azimuthal direction on the base and on the surface of the nozzle. The signals are spectrally analyzed with the objective to characterize and identify unsteady flow effects in order to reduce base drag and vibrations of future space launchers. The base-pressure spectra exhibits global modes at Strouhal numbers of 0.05 to 0.06, 0.09 to 0.1 and 0.2 to 0.25, which are attributed in literature to flapping and shedding. Local modes seem to occur Locally restricted modes can be detected for the tonal disturbances in the high frequency range for transducers on the base closer to the nozzle. The increase of the reservoir pressure shows a consistent increase of the pressure fluctuation level in the base region.