Pulsed-Jet Ejector Thrust Augumentor Characteristics

Abstract

An experimental study is carried out to investigate the characteristics of a pulsed-jet ejector thrust augmentor that is suitable for use in vertical take-off and landing aircraft. Phase-locked particle image velocimetry is used to obtain the detailed spatio-temporal evolution of the ejector flowfield. Experiments were carried out to determine the conditions formaximum thrust augmentation. In the presence of the ejector, the pulsed-jet primary vortex induces a secondary vortex at the ejector wall. The peak vorticity magnitude of the primary vortex was found to be at a maximum at the condition of maximum thrust augmentation. The presence of this primary and secondary vortex pair results in enhancedmass entrainment andmixing, which, in turn, produces increased thrust augmentation. The nonmonotonic variation of the thrust augmentation ratio with the ejector area ratio (ejector inlet area/nozzle exit area) is largely determined by the peak vorticity magnitude of the primary-vortex ring and the secondary vortex.