Article
Acoustics
Chitrarth Prasad, Philip J. Morris
Summary: The study investigates the effect of using fluid inserts for noise control at high exhaust temperatures through large eddy simulations. It reveals a reduction in radiation efficiency of Mach waves from the controlled jet, with more pronounced effect at afterburner conditions. The effectiveness of fluid inserts improves with increasing jet exhaust temperature, achieving noise reduction with a conservative thrust loss estimate of under 2% at both laboratory and afterburner operating conditions.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(2021)
Article
Acoustics
Kevin M. Leete, Kent L. Gee, Junhui Liu, Alan T. Wall
Summary: In this study, near-field acoustical holography (NAH) was used to virtually measure the near-field pressures of a highly heated laboratory-scale supersonic jet. The holographic reconstructions matched well with the results from large-eddy simulation (LES), allowing the calculation of the jet's acoustic power and efficiency.
JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
(2022)
Article
Engineering, Aerospace
Arun Kumar Perumal, Ethirajan Rathakrishnan
Summary: This experiment investigates the effect of fluidic injection on the mixing of a Mach 2.0 round jet and proposes a new scaling law for efficient jet manipulation. The results demonstrate that fluidic injectors provide an effective flow control mechanism for jet mixing applications compared to the elliptic jet.
Article
Engineering, Mechanical
Kyle A. Daniel, David E. Mayo, K. Todd Lowe, Wing F. Ng
Summary: This study presents analyses of high-speed schlieren images to illustrate the spatio-temporal structure of near-field sound in uniformly and non-uniformly heated supersonic round jets. The non-uniformly heated jet is found to reduce jet noise compared to the uniform jet, demonstrating a decrease of up to 2 +/- 0.5 dB in the peak narrowband sound pressure level. Space-time correlations, path integration effects, and hydrodynamic structures are evaluated, showing modifications by thermal non-uniformity in different regions of the jet. The perturbations induced by the thermal non-uniformity are shown to persist far into the developing flow field, suggesting potential optimization of centerline base flow changes to reduce acoustic efficiency near noise-producing areas.
EXPERIMENTS IN FLUIDS
(2022)
Article
Astronomy & Astrophysics
Michael D. Smith, Carl Richards
Summary: The Mach number is a crucial parameter in determining the driving properties and impact on the environment of a supersonic jet. Through numerical simulations, we investigate the effects of different Mach numbers and jet overpressures on the flow pattern and shock locations. We also analyze potential observational diagnostics and the energy transferred into the environment.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Environmental Sciences
Jens von der Linden, Clare Kimblin, Ian McKenna, Skyler Bagley, Hsiao-Chi Li, Ryan Houim, Christopher S. Kueny, Allen Kuhl, Dave Grote, Mark Converse, Caron E. J. Vossen, Soenke Stern, Corrado Cimarelli, Jason Sears
Summary: The text discusses how sparks and standing shocks observed in shock tube experiments regulate electrical breakdown, and how radio frequency signatures emitted by volcanic eruptions can diagnose fluid dynamic and electrostatic conditions. Research shows that sparks are initiated in a rarefaction region and cut off at the shock, limiting their radio frequency emissions to a characteristic frequency range.
COMMUNICATIONS EARTH & ENVIRONMENT
(2021)
Article
Nanoscience & Nanotechnology
P. Pineau, C. Bogey
Summary: The study investigates the effects of jet interactions and acoustic shielding on the noise of strongly heated supersonic twin jets through large-eddy simulations. It reveals that jet interactions can weaken some sound sources, leading to an overall reduction in acoustic power. Despite the noise reduction, some noise components are stronger for twin jets, indicating the generation of additional interaction noise.
Article
Mechanics
Dan Fries, Devesh Ranjan, Suresh Menon
Summary: The study investigates flow fields and trajectories of sonic jets in a supersonic cross-flow with different injectant properties. Results show that different factors have varying influences at different J values, with boundary layer and bow shock playing key roles in trajectory development.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
S. Demange, U. A. Qadri, M. P. Juniper, F. Pinna
Summary: This study investigates the stability features of spatially spreading heated jets in the viscous regime with real gas effects, using both unsteady two-dimensional axisymmetric simulations and linear analyses. The study confirms that including real gas effects in the stability equations has a strong effect on the growth rate of the global mode. Linear global analyses over the time-averaged states provide a satisfying prediction of the oscillation's frequency and the baroclinic torque obtained from the resulting global mode matches well with that of the simulations.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Daniel Edgington-Mitchell, Tianye Wang, Petronio Nogueira, Oliver Schmidt, Vincent Jaunet, Daniel Duke, Peter Jordan, Aaron Towne
Summary: The interaction between various wave-like structures in screeching jets has been studied using experimental measurements and linear stability theory. Three distinct wave-like structures have been identified, including the well-known Kelvin-Helmholtz mode and the recently discussed guided jet mode.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
Shahram Karami, Julio Soria
Summary: This study uses large-eddy simulations to investigate the influence of nozzle external geometry on upstream-travelling waves in under-expanded supersonic jets. It is found that the external geometry significantly affects the first-order statistics and leads to multiple peaks in the energy spectra at distinct frequencies. Different forms of upstream-travelling wavepackets contribute to the receptivity process with their contributions and strength altered by the change of the external geometry of the nozzle.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Mechanical
Mark P. Wernet, Nicholas J. Georgiadis, Randy J. Locke
Summary: This study utilizes Raman spectroscopy measurement techniques to achieve gas density measurement in supersonic jets, further enhancing the measurement of flow field properties. These non-intrusive flow measurement methods are used to assess the accuracy of RANS predictions of supersonic jet properties.
EXPERIMENTS IN FLUIDS
(2021)
Article
Computer Science, Information Systems
Ian McLane, Eline Lauwers, Toon Stas, Ilene Busch-Vishniac, Kris Ides, Stijn Verhulst, Jan Steckel
Summary: This study presents a comprehensive signal analysis method for analyzing challenging recordings of crackles, which performs well and exhibits high accuracy in crackle detection. By utilizing a combination of new methods and robustness-focused improvements, the system can assist clinicians in better understanding respiratory sounds non-invasively to differentiate between different types of crackles.
IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS
(2022)
Article
Mechanics
J. Liu, S. Cong, Y. Song, S. Chen, D. Wu
Summary: This paper investigates the acoustic characterization of vertical downward underwater supersonic gas jets and conducts numerical simulations for different jet conditions. The results show good agreement between simulations and experiments, indicating that computational fluid dynamics can be used to understand the physics behind underwater gas jet noise and further study the blowing of gas jets into water.
Article
Engineering, Aerospace
Jan Siemen Smink, Harry W. M. Hoeijmakers, Cornelis H. Venner
Summary: This study investigated the mixing process of tandem dual-jet injection in a supersonic wind tunnel and established an empirical similarity relation between the jet shear layer position and the jet momentum and spacing.