Directivity Effects of Shaped Plumes from Plug Nozzles

2013 ◽  
Author(s):  
James Chase ◽  
Andres Garzon ◽  
Dimitri Papamoschou
Keyword(s):  
Plug Nozzles ◽  
Directivity Effects

scholarly journals Rupture Directivity in 3D Inferred From Acoustic Emissions Events in a Mine-Scale Hydraulic Fracturing Experiment

2021 ◽  
Vol 9 ◽  
Author(s):  
José Ángel López-Comino ◽  
Simone Cesca ◽  
Peter Niemz ◽  
Torsten Dahm ◽  
Arno Zang
Keyword(s):  
Hydraulic Fracturing ◽  
Acoustic Emissions ◽  
Local Stress ◽  
Horizontal Stress ◽  
Monitoring Networks ◽  
Rupture Directivity ◽  
Shallow Subsurface ◽  
Minimum Horizontal Stress ◽  
Directivity Effects ◽  
Full Waveforms

Rupture directivity, implying a predominant earthquake rupture propagation direction, is typically inferred upon the identification of 2D azimuthal patterns of seismic observations for weak to large earthquakes using surface-monitoring networks. However, the recent increase of 3D monitoring networks deployed in the shallow subsurface and underground laboratories toward the monitoring of microseismicity allows to extend the directivity analysis to 3D modeling, beyond the usual range of magnitudes. The high-quality full waveforms recorded for the largest, decimeter-scale acoustic emission (AE) events during a meter-scale hydraulic fracturing experiment in granites at ∼410 m depth allow us to resolve the apparent durations observed at each AE sensor to analyze 3D-directivity effects. Unilateral and (asymmetric) bilateral ruptures are then characterized by the introduction of a parameter κ, representing the angle between the directivity vector and the station vector. While the cloud of AE activity indicates the planes of the hydrofractures, the resolved directivity vectors show off-plane orientations, indicating that rupture planes of microfractures on a scale of centimeters have different geometries. Our results reveal a general alignment of the rupture directivity with the orientation of the minimum horizontal stress, implying that not only the slip direction but also the fracture growth produced by the fluid injections is controlled by the local stress conditions.

Thrust Nozzles for Supersonic Transport Aircraft

1964 ◽  
Vol 86 (2) ◽  
pp. 97-104 ◽  
Author(s):  
David Migdal ◽  
John J. Horgan
Keyword(s):  
External Flow ◽  
Operating Costs ◽  
Jet Engine ◽  
Transport Aircraft ◽  
Supersonic Transport ◽  
The Past ◽  
Engine Thrust ◽  
Performance Trends ◽  
Flow Effects ◽  
Plug Nozzles

Supersonic transports will require jet-engine thrust nozzles that are highly efficient from take-off to supersonic cruise in order to minimize the direct operating costs. Variable-area ejectors, plug nozzles, and modifications of these basic types have been tested extensively during the past several years. Performance trends for these nozzles are presented with the emphasis on external flow effects. A new ejector which utilizes aerodynamically actuated doors to admit external air into the ejector shroud is discussed.

Comparison of Ground Motions from Hybrid Simulations to NGA Prediction Equations

2011 ◽  
Vol 27 (2) ◽  
pp. 331-350 ◽  
Author(s):  
Lisa M. Star ◽  
Jonathan P. Stewart ◽  
Robert W. Graves
Keyword(s):  
Ground Motions ◽  
Rupture Directivity ◽  
Ground Motion Prediction Equations ◽  
Fault Rupture ◽  
Prediction Equations ◽  
San Andreas ◽  
Blind Thrust ◽  
Static Stress Drop ◽  
Basin Response ◽  
Directivity Effects

We compare simulated motions for a Mw 7.8 rupture scenario on the San Andreas Fault known as the ShakeOut event, two permutations with different hypocenter locations, and a Mw 7.15 Puente Hills blind thrust scenario, to median and dispersion predictions from empirical NGA ground motion prediction equations. We find the simulated motions attenuate faster with distance than is predicted by the NGA models for periods less than about 5.0 s After removing this distance attenuation bias, the average residuals of the simulated events (i.e., event terms) are generally within the scatter of empirical event terms, although the ShakeOut simulation appears to be a high static stress drop event. The intra-event dispersion in the simulations is lower than NGA values at short periods and abruptly increases at 1.0 s due to different simulation procedures at short and long periods. The simulated motions have a depth-dependent basin response similar to the NGA models, and also show complex effects in which stronger basin response occurs when the fault rupture transmits energy into a basin at low angle, which is not predicted by the NGA models. Rupture directivity effects are found to scale with the isochrone parameter.

Experimental and numerical analysis of linear plug nozzles

1998 ◽  
Author(s):  
H. Immich ◽  
F. Nasuti ◽  
M. Onofri ◽  
M. Caporicci
Keyword(s):  
Numerical Analysis ◽  
Plug Nozzles

Free Turbulent Shear Layers on Plug Nozzles

1977 ◽  
Vol 99 (2) ◽  
pp. 301-308
Author(s):  
C. J. Scott ◽  
D. R. Rask
Keyword(s):  
Turbulent Mixing ◽  
Schmidt Number ◽  
Error Function ◽  
Mixing Layer ◽  
Shear Layers ◽  
Turbulent Shear ◽  
Gas Chromatograph ◽  
Plug Nozzle ◽  
Turbulent Schmidt Number ◽  
Plug Nozzles

Two-dimensional, free, turbulent mixing between a uniform stream and a cavity flow is investigated experimentally in a plug nozzle, a geometry that generates idealized mixing layer conditions. Upstream viscous layer effects are minimized through the use of a sharp-expansion plug nozzle. Experimental velocity profiles exhibit close agreement with both similarity analyses and with error function predictions. Refrigerant-12 was injected into the cavity and concentration profiles were obtained using a gas chromatograph. Spreading factors for momentum and mass were determined. Two methods are presented to determine the average turbulent Schmidt number. The relation Sct = Sc is suggested by the data for Sc < 2.0.

Methodology to Solve Flowfields of Plug Nozzles for Future Launchers

1998 ◽  
Vol 14 (3) ◽  
pp. 318-326 ◽  
Author(s):  
Francesco Nasuti ◽  
Marcello Onofri
Keyword(s):  
Plug Nozzles

Some geotechnical aspects of the Hyogo-ken Nanbu (Kobe) earthquake of January 17, 1995

1996 ◽  
Vol 23 (3) ◽  
pp. 778-796 ◽  
Author(s):  
W. D. Liam Finn ◽  
P. M. Byrne ◽  
S. Evans ◽  
T. Law
Keyword(s):  
Soil Structure ◽  
Large Scale ◽  
Ground Improvement ◽  
Lateral Spreading ◽  
Bridge Piers ◽  
Soil Conditions ◽  
Kobe Earthquake ◽  
Port Facilities ◽  
Underground Subway Station ◽  
Directivity Effects

A geological and seismological framework is provided for understanding the damage to structures resulting from soil conditions. The paper focusses on the large-scale failures of the quay walls in Kobe Port due to liquefaction, and contrasts the performance of structures in improved and unimproved ground. Soil–structure interaction problems such as pile foundations, bridge piers, lifelines, and an underground subway station are also described. These failures have important implications for seismic design in the Fraser Delta in British Columbia, which has the potential for extensive liquefaction during a major earthquake. Key words: ground motions, directivity effects, liquefaction, lateral spreading, seismic settlements, seismic damage, port facilities, ground improvement.

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