English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

A wave-packet ansatz is used to model noise generation by organized, large-scale structures. The spectrum of the acoustic fleld is expressed in terms of two-point space-time correlations of hydrodynamic pressure on a conical surface surrounding the jet plume. The surface is su‐ciently near the turbulent ∞ow region to be dominated by hydrodynamic disturbances, yet su‐ciently far that the wave equation can be used to project the nearfleld pressure to the acoustic fleld. In the present study, a 78-microphone array was used to measure hydrodynamic pressure on the conical surface at a variety of acoustic Mach numbers and temperature ratios. At each jet cross section, 6 microphones are staggered in the azimuthal direction allowing resolution of pressure up to azimuthal mode number m=2. We compare recent jet noise measurements using an 80-microphone conical mid-fleld array with those derived from the near-fleld hydrodynamic array data, showing reasonably good predictions. Source model parameters are identifled for various jet temperature ratios. Results show that changes in jet noise directivity with heating can be attributed to contraction of the wave-packet scale.

Modeling Jet Noise from Organized Structures Using Near-Field Hydrodynamic Pressure