Impact of Fluidic Chevrons on Supersonic Jet Noise

The impact of fluidic chevrons on broadband shock noise and mixing noise for single stream and coannular jets was investigated. Air was injected into the core flow of a bypass ratio 5 nozzle system using a core fluidic chevron nozzle. For the single stream experiments, the fan stream was operated at the wind tunnel conditions and the core stream was operated at supersonic speeds. For the dual stream experiments, the fan stream was operated at supersonic speeds and the core stream was varied between subsonic and supersonic conditions. For the single stream jet at nozzle pressure ratio (NPR) below 2.0, increasing the injection pressure of the fluidic chevron increased high frequency noise at observation angles upstream of the nozzle exit and decreased mixing noise near the peak jet noise angle. When the NPR increased to a point where broadband shock noise dominated the acoustic spectra at upstream observation angles, the fluidic chevrons significantly decreased this noise. For dual stream jets, the fluidic chevrons reduced broadband shock noise levels when the fan NPR was below 2.3, but had little or no impact on shock noise with further increases in fan pressure. For all fan stream conditions investigated, the fluidic chevron became more effective at reducing mixing noise near the peak jet noise angle as the core pressure increased

Open-Ended Questions in Reading

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Mind the Gap: Fostering Scholarship-into-Practice for Advanced Practice Nursing Students through Embedded Librarianship

In recent years, librarianship has been increasingly recognized as a critical component of inter-professional healthcare education. This manuscript describes how innovative coordination between libraries and university healthcare programs can remove the barriers to scholarship for graduate students who enroll in distance education (DE) programs. The authors examined the perceived impact of librarian embedment for DE nursing students graduating with master’s degrees from George Washington University in 2013. Librarians were embedded in the first course in which they were enrolled in 2010 to support the mastery of scientific research skills. Analysis indicated that students strongly agreed that contact with embedded librarians in DE courses at the onset of a graduate school, improved their ability to engage in scholarly activities throughout their program of study. It also facilitated the integration of scholarship into practice (required for school accreditation) by allowing them to expeditiously retrieve research from databases and generate evidence for patient care delivery

Impact of Azimuthally Controlled Fluidic Chevrons on Jet Noise

The impact of azimuthally controlled air injection on broadband shock noise and mixing noise for single and dual stream jets was investigated. The single stream experiments focused on noise reduction for low supersonic jet exhausts. Dual stream experiments included high subsonic core and fan conditions and supersonic fan conditions with transonic core conditions. For the dual stream experiments, air was injected into the core stream. Significant reductions in broadband shock noise were achieved in a single jet with an injection mass flow equal to 1.2% of the core mass flow. Injection near the pylon produced greater broadband shock noise reductions than injection at other locations around the nozzle periphery. Air injection into the core stream did not result in broadband shock noise reduction in dual stream jets. Fluidic injection resulted in some mixing noise reductions for both the single and dual stream jets. For subsonic fan and core conditions, the lowest noise levels were obtained when injecting on the side of the nozzle closest to the microphone axis