Impact Region of Nonbuoyant Orthogonal Discharge

2021 ◽  
Vol 147 (12) ◽  
Author(s):  
A. Ramakanth ◽  
M. J. Davidson ◽  
R. I. Nokes
Keyword(s):  
Impact Region

Simplified Transient Numerical Model of a Supersonic Jet Impacting a Substrate

2017 ◽  
Author(s):  
Sichang Xu ◽  
Patrick Pomerleau-Perron ◽  
Gary W. Rankin
Keyword(s):  
Flow Field ◽  
Numerical Solutions ◽  
Transient Flow ◽  
Fluid Dynamic ◽  
Supersonic Jet ◽  
Axially Symmetric ◽  
Rotary Valve ◽  
Time Curve ◽  
Jet Impact ◽  
Impact Region

The transient flow field near the surface of a substrate impacted by a pulsating supersonic jet emerging from a long tube is investigated using a simplified axially symmetric numerical approach. In the system being modeled, the pulses are created using a rotary valve located at the tube entrance. This flow situation approximates the conditions existing in the Shock-Induced Cold Spray process for coating surfaces with metallic particles. Previous numerical studies of transient supersonic jets either focused on jets emerging from orifices or did not give details of the complex supersonic flow field in the jet impact region. The current approximate numerical method considers the flow within the long tube and in the jet impact region. The procedure involves two stages. The upstream pressure variation with time is first determined using a one-dimensional compressible flow approximation of the entire tube and rotary valve arrangement. The resulting pressure versus time curve serves as the transient inlet boundary condition for an axially symmetric computational fluid dynamic solution of the flow through the tube and region of jet impact on the substrate. The numerical solutions of substrate pressure on the jet centerline versus time are compared with available experimental results and predict certain general features of the substrate pressure traces. Although the simplified model is only in fair agreement with some aspects of the experimental curves, it is shown to be useful in explaining certain peculiar flow features. With the aid of the numerical solution, an explanation for the movement and instability of the bow shock wave which forms ahead of the substrate is described.

The Impact of an Axisymmetric Jet onto a Normal Ground

1972 ◽  
Vol 23 (2) ◽  
pp. 141-147 ◽  
Author(s):  
L J S Bradbury
Keyword(s):  
Static Pressure ◽  
Simple Argument ◽  
Axisymmetric Jet ◽  
Dynamic Head ◽  
Aircraft Aerodynamics ◽  
The Impact ◽  
Vtol Aircraft ◽  
Impact Region

SummaryThe impact of an axisymmetric jet onto a ground board is a flow of some interest in VTOL aircraft aerodynamics. This paper presents a simple argument for correlating data obtained in the impact region from different nozzle configurations and for different nozzle heights above ground. The argument is applied, in particular, to the static pressure on the ground board and to the peak dynamic head in the flow over the ground board.

scholarly journals Optical spectra of FO Aquarii during low and high accretion rates

2020 ◽  
Vol 495 (4) ◽  
pp. 4445-4462
Author(s):  
M R Kennedy ◽  
P M Garnavich ◽  
C Littlefield ◽  
T R Marsh ◽  
P Callanan ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Accretion Disc ◽  
High State ◽  
Secondary Star ◽  
Accretion Rates ◽  
Magnetic Poles ◽  
The Impact ◽  
Impact Region

ABSTRACT Between 2016 May and 2018 September, the intermediate polar (IP) FO Aquarii exhibited two distinct low states and one failed low state. We present optical spectroscopy of FO Aquarii throughout this period, making this the first detailed study of an accretion disc during a low state in any IP. Analysis of these data confirm that the low states are the result of a drop in the mass transfer rate between the secondary star and the magnetic white dwarf primary, and are characterized by a decrease in the system’s brightness coupled with a change of the system’s accretion structures from an accretion disc-fed geometry to a combination of disc-fed and ballistic stream-fed accretion, and that effects from accretion on to both magnetic poles become detectable. The failed low state only displays a decrease in brightness, with the accretion geometry remaining primarily disc-fed. We also find that the WD appears to be exclusively accretion disc-fed during the high state. There is evidence for an outflow close to the impact region between the ballistic stream and the disc which is detectable in all of the states. Finally, there is marginal evidence for narrow high-velocity features in the H α emission line during the low states which may arise due to an outflow from the WD. These features may be evidence of a collimated jet, a long predicted yet elusive feature of cataclysmic variables.

S0510302 Evaluation of Jet Impact Region Generated from Ruptured Pipes : (2) Evaluation of Fluid Force Using CFD and Comparison with Established Standards

2015 ◽  
Vol 2015 (0) ◽  
pp. _S0510302--_S0510302-
Author(s):  
Shiro TAKAHASHI ◽  
Noriyuki TAKAMURA ◽  
Qiang XU ◽  
Ryo MORITA ◽  
Yuta UCHIYAMA ◽  
...  
Keyword(s):  
Fluid Force ◽  
Jet Impact ◽  
Impact Region

S0510301 Evaluation of Jet Impact Region Generated from Ruptured Pipes : (1) Numerical Evaluation of Asymptotic Region and Comparison with Established Standards

2015 ◽  
Vol 2015 (0) ◽  
pp. _S0510301--_S0510301-
Author(s):  
Ryo MORITA ◽  
Yuta UCHIYAMA ◽  
Shun WANATABE ◽  
Shiro TAKAHASHI ◽  
Noriyuki TAKAMURA ◽  
...  
Keyword(s):  
Numerical Evaluation ◽  
Asymptotic Region ◽  
Jet Impact ◽  
Impact Region

Hydroelastic Modeling of Wet Deck Slamming on Multihull Vessels

2021 ◽  
Vol 39 (03) ◽  
pp. 225-239
Author(s):  
Jan Kvalsvold ◽  
Odd M. Faltinsen
Keyword(s):  
Water Surface ◽  
Normal Modes ◽  
Two Dimensional ◽  
Sea Waves ◽  
Rotatory Inertia ◽  
Shear Deformations ◽  
Inertia Effects ◽  
Elastic Stresses ◽  
The Impact ◽  
Impact Region

Slamming against the wet deck of a multihull vessel in head sea waves is studied analytically and numerically. The theoretical slamming model is a two-dimensional, asymptotic method valid for small local angles between the undisturbed water surface and the wet deck in the impact region. The disturbance of the water surface as well as the local hydroelastic effects in the slamming area are accounted for. The elastic deflections of the wet deck are expressed in terms of "dry" normal modes. The structural formu­lation accounts for the shear deformations and the rotatory inertia effects in the wet deck. The findings show that the slamming loads on the wet deck and the resulting elastic stresses in the wet deck are strongly influenced by the elasticity of the wet deck structure.

STUDY AND APPLICATION OF UNDERWATER NOISE IMPACT IN COASTAL REGION OFF WESTERN TAIWAN

2014 ◽  
Vol 22 (01) ◽  
pp. 1440007
Author(s):  
YU-CHEN CHENG ◽  
SHENG-FONG LIN ◽  
YUAN-YING CHANG ◽  
CHI-FANG CHEN ◽  
CHEN-FAR HUNG ◽  
...  
Keyword(s):  
Impulsive Noise ◽  
Wind Farms ◽  
Propagation Model ◽  
Offshore Wind ◽  
Western Coast ◽  
Underwater Sound ◽  
Underwater Noise ◽  
Source Modeling ◽  
Noise Impact ◽  
Impact Region

Offshore wind farms are the main project on Taiwan's western coast. Since the underwater noise generated by piling poses a threat to marine mammals, the issue of the detrimental impact of noise on Sousa Chinensis has drawn considerable attention. To avoid behavioral disturbances and injury from pile driving noise, we propose the Underwater Noise Impact Region Alert System (UNIRAS) to estimate the acoustic field at any depth and distance from the piling sources. The system can be illustrated as four components: environment databases, an acoustic propagation model, source modeling and alert region (AR) prediction. Inputs are derived from the Taiwan Coastal Ocean Nowcast/Forecast System (TCONFS), which generates underwater sound speed profiles with temporal and spatial variation, along with geoacoustic and bathymetry databases that are imported as environmental inputs. Adiabatic mode theory is used to simulate the piling noise propagation in shallow water and the impulsive noise emanating from the source is evaluated via the finite element method. With the auditory threshold of cetacean being set as the criterion level, the system can demonstrate the modeling outputs and predict the noise impact region, and these results are useful for planning how to station the guard boats to prevent dolphins from entering the noise impact region.

scholarly journals Aeration and deaeration at bottom aeration devices on spillways

1994 ◽  
Vol 21 (3) ◽  
pp. 404-409 ◽  
Author(s):  
Hubert Chanson
Keyword(s):  
High Velocity ◽  
Flow Characteristics ◽  
Air Entrainment ◽  
Air Concentration ◽  
Concentration Data ◽  
Cavitation Damage ◽  
Downstream Flow ◽  
Bottom Outlets ◽  
The Impact ◽  
Impact Region

Aeration devices are introduced along chute spillways and at bottom outlets to prevent cavitation damage in high velocity flows. Bottom aerators are characterized by large quantities of air entrained along the jet interfaces and also by a strong deaeration process near the impact of the water jet with the spillway bottom. In this paper, the aeration and deaeration occurring respectively in the aeration region and in the impact region are reviewed. A reanalysis of air concentration data obtained on models provides information on the flow characteristics at the end of the impact region. These results enable an accurate initialization of the downstream flow calculations using the method developed by Chanson. Key words: bottom aeration devices, aerators, spillways, air entrainment, detrainment.

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