Modeling a decrease in hydraulic losses during turbulent flow in a U-bend channel with a circular cavern with a large opening angle

2015 ◽  
Vol 41 (3) ◽  
pp. 298-300 ◽  
Author(s):  
S. A. Isaev ◽  
E. I. Kalinin ◽  
A. A. Tereshkin ◽  
A. E. Usachov
Keyword(s):  
Turbulent Flow ◽  
Opening Angle ◽  
Hydraulic Losses ◽  
Bend Channel ◽  
Large Opening

scholarly journals Revealing the Mass Loss Structures of Four Key Massive Binaries Using Optical Spectropolarimetry

2014 ◽  
Vol 9 (S307) ◽  
pp. 336-341
Author(s):  
Jamie R. Lomax
Keyword(s):  
Mass Loss ◽  
Binary Systems ◽  
Hot Spot ◽  
Polarized Light ◽  
Opening Angle ◽  
Geometric Information ◽  
Intrinsic Polarization ◽  
Polarization Component ◽  
Circumstellar Material ◽  
Large Opening

AbstractThe majority of massive stars are members of binary systems. However, in order to understand their evolutionary pathways, mass and angular momentum loss from these systems needs to be well characterized. Self-consistent explanations for their behavior across many wavelength regimes need to be valid in order to illuminate key evolutionary phases. I present the results of linear spectropolarimetric studies of three key binaries (β Lyrae, V356 Sgr, V444 Cyg, and WR 140) which reveal important geometric information about their circumstellar material. β Lyrae exhibits a repeatable discrepancy between secondary eclipse in the total and polarized light curves that indicates an accretion hot spot has formed on the edge of the disk in the system. The existence of this hot spot and its relationship to bipolar outflows within the system is important in the understanding of mass transfer dynamics in Roche-lobe overflow binaries. Preliminary work on V356 Sgr suggests the system maybe surrounded by a common envelope. V444 Cyg shows evidence that its shock creates a cone with a large opening angle of missing material around the WN star. This suggests the effects of radiative inhibition or braking, can be significant contributors to the location and shape of the shock within colliding wind binaries. The intrinsic polarization component of WR 140 is likely due to the formation of dust within the system near periastron passages. Continued work on these and additional objects will provide new and important constraints on the mass loss structures within binary systems.

Flow Patterns Downstream of a Mechanical Heart Valve During Systole

2007 ◽  
Author(s):  
P. Oshkai ◽  
F. Haji-Esmaeili
Keyword(s):  
Turbulent Flow ◽  
Heart Valve ◽  
Large Scale ◽  
Cardiac Cycle ◽  
Mechanical Heart Valve ◽  
Opening Angle ◽  
Image Velocimetry ◽  
Imaging Approach ◽  
Systolic Phase ◽  
Flow Through

Digital particle image velocimetry is employed to study turbulent flow through a bileaflet mechanical heart valve during systolic phase of a cardiac cycle. Unsteady vortex shedding from the valve’s leaflets displays distinct characteristic frequencies, depending on the opening angle of each leaflet. Small- and large-scale transverse oscillations of the separated shear layers are studied using global quantitative flow imaging approach. Turbulent flow structures including jet-like regions and shed vortices are characterized in terms of patterns of instantaneous and time-averaged velocity, vorticity, and turbulence statistics.

scholarly journals Hubble Space Telescope Imaging of the Disks and Jets of Taurus Young Stellar Objects

1997 ◽  
Vol 182 ◽  
pp. 355-364 ◽  
Author(s):  
Karl Stapelfeldt ◽  
Christopher J. Burrows ◽  
John E. Krist ◽  
Keyword(s):  
High Spatial Resolution ◽  
Hubble Space Telescope ◽  
Scattered Light ◽  
Young Stellar Objects ◽  
Opening Angle ◽  
Stellar Objects ◽  
Space Telescope ◽  
Spread Function ◽  
Large Opening ◽  
T Tau

We report on Hubble Space Telescope imaging of eleven young stellar objects in the nearby Taurus molecular clouds. The high spatial resolution and stable point spread function of HST reveal important new details of the circumstellar nebulosity of these objects. Three sources (HH 30, FS Tau B, and DG Tau B) are resolved as compact bipolar nebulae without a directly visible star. In all three cases, jet widths near the sources are found to be 50 AU or less. Flattened disk structures are seen in absorption in HH 30 and FS Tau B, and in reflection about GM Aur. Extended envelope structures traced by scattered light are present in HL Tau, T Tau, DG Tau, and FS Tau. The jet in DG Tau exhibits a large opening angle and is already resolved into a bow-like structure less than 3″ from the star.

scholarly journals The nature of a primary jet within a circumbinary disc outflow in a young stellar system

2020 ◽  
Vol 494 (2) ◽  
pp. 2299-2311
Author(s):  
Chris J R Lynch ◽  
Michael D Smith
Keyword(s):  
Ambient Medium ◽  
Stellar System ◽  
Three Dimensional ◽  
Pulse Amplitude ◽  
Young Star ◽  
Opening Angle ◽  
Molecular Outflow ◽  
Axis Alignment ◽  
Large Opening ◽  
Set Up

ABSTRACT Most stars form in binaries, and both stars may grow by accreting material from a circumbinary disc on to their own discs. We suspect that in many cases a wide molecular wind will envelope a collimated atomic jet emanating from close to an orbiting young star. This so-called circumbinary scenario is explored here in order to find common identifiable properties. The dynamical set-up is studied with three-dimensional simulations with chemistry and cooling included. We extract the properties on scales of order 100 au and compare to the co-orbital scenario in which the wind and jet sources are in orbit. We find that the rapid orbital motion generates a wide ionized sheath around the jet core with a large opening angle at the base. This is independent of the presence of the surrounding molecular outflow. However, the atomic jet is recollimated beyond ∼55 au when the molecular outflow restricts the motion of the ambient medium which, in turn, confines the jet. These physical properties are related to the optical H α imaging, providing a means of distinguishing between models. The high excitation sheath and recollimation region can be explored on these scales through the next generation of instruments. However, in general, the amount and location of the ionized material, whether in the knots or the sheath, will depend on several parameters including the orbital period, axis alignment, and pulse amplitude.

The flow of a viscous fluid inside a confuser with large opening angle

2002 ◽  
Vol 47 (9) ◽  
pp. 698-701
Author(s):  
L. D. Akulenko ◽  
D. V. Georgievskii ◽  
S. A. Kumakshev
Keyword(s):  
Viscous Fluid ◽  
Opening Angle ◽  
Large Opening

Optimization of an Additively Manufactured U-Bend Channel Using A Surrogate-Based Bayesian Method

2021 ◽  
Author(s):  
Shinjan Ghosh ◽  
Sudeepta Mondal ◽  
Ryan Wardell ◽  
Erik Fernandez ◽  
Jayanta S. Kapat ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Turbulent Flow ◽  
Design Space ◽  
Cfd Simulation ◽  
Turbine Blades ◽  
Latin Hypercube Sampling ◽  
Pressure Profile ◽  
Optimum Shape ◽  
Data Set ◽  
Bend Channel

Abstract CFD-based design optimization of turbulent flow scenarios is usually computationally expensive due to requirement of high-fidelity simulations. Previous studies prove that one way to reduce computational resource usage is to employ Machine Learning/Surrogate Modeling approaches for intelligent sampling of data points in the design space and is also an active area of research, but lacks enough experimental validation. Such a method has been used to optimize the shape of a U-bend channel for the minimization of pressure drop. U-bends are an integral part of serpentine cooling channels inside gas turbine blades but also contribute to total pressure drop by more than 20%. Reducing this pressure loss can help in more efficient cooling at low pumping power. A ‘U-bend’ or 180-degree bend shape has been used from literature, and a 16-dimensional design space has been created using parametrized spline curves, which creates a variety of shapes inside a given bounding box. A Latin Hypercube Sampling (LHS) was carried out for populating the initial design space with output data from the CFD simulation. After training a surrogate model on this data set, Bayesian updates were used to search for an optimum using an exploration vs exploitation approach. The resulting optimum shape showed that pressure drop was lowered by almost 30%, when compared to the baseline. The aim of this study is to experimentally validate this method using 3D printed models of the baseline and optimum channels respectively. Pressure taps placed across stream-wise locations on these channels helped to create a pressure profile for turbulent flow at a Reynolds number of 17000, for comparison to CFD results.

scholarly journals AGN and Star Formation Feedback in Galaxy Outflows

2018 ◽  
Vol 14 (S342) ◽  
pp. 229-233
Author(s):  
Elisabete M. de Gouveia Dal Pino ◽  
William Clavijo-Bohórquez ◽  
Claudio Melioli
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Three Dimensional ◽  
Active Galaxies ◽  
Opening Angle ◽  
Mass Loading ◽  
Nuclear Region ◽  
Molecular Outflows ◽  
Mhd Simulations ◽  
Large Opening

AbstractLarge-scale, broad outflows are common in active galaxies. In systems where star formation coexists with an AGN, it is unclear yet the role that both play on driving the outflows. In this work we present three-dimensional radiative-cooling MHD simulations of the formation of these outflows, considering the feedback from both the AGN and supernovae-driven winds. We find that a large-opening-angle AGN wind develops fountain structures that make the expanding gas to fallback. Furthermore, it exhausts the gas near the nuclear region, extinguishing star formation and accretion within a few 100.000 yr, which establishes the duty cycle of these outflows. The AGN wind accounts for the highest speed features in the outflow with velocities around 10.000 km s−1 (as observed in UFOs), but these are not as cold and dense as required by observations of molecular outflows. The SNe-driven wind is the main responsible for the observed mass-loading of the outflows.

scholarly journals Numerical Simulation and Experiment of Hydraulic Loss of Two-Stage Flap Valves

2021 ◽  
Author(s):  
Bingnan Zhou ◽  
Weigang Lu ◽  
Bo Xu ◽  
Hua Chen
Keyword(s):  
Numerical Simulation ◽  
Opening Angle ◽  
Hydraulic Loss ◽  
Two Stage ◽  
Pump Station ◽  
Simulation And Experiment ◽  
Large Opening ◽  
Relationship Of ◽  
The Relationship ◽  
Flap Valve

As a type of flap valve evolved from integral flap valve, two-stage flap valve has the advantages of large opening angle, small hydraulic loss and small impact force on the flap valve seat when the flap valve is closed. In order to analyze and study the hydraulic loss characteristics of the two-stage flap valve, this paper takes a pump station as an example. Based on theoretical analysis, combined with numerical simulation and model test, the hydraulic loss of two-stage flap valve is studied, and the relationship between hydraulic loss and pump station flow is obtained. According to the test results, the hydraulic loss of two-stage flap valve increases with the increase of flow rate under the same opening angle of flap valve. Under the same flow condition, the larger the opening angle of the flap valve is, the smaller the hydraulic loss of the two-stage flap valve is. When the opening angle of the upper flap valve is greater than 46° and the opening angle of the lower flap valve is greater than 64°, the hydraulic loss is less than 70mm and tends to be stable. The influence of hydraulic loss on the performance of pump device is gradually weakened. The relationship between hydraulic loss and flow of two-stage flap valve no longer satisfies the relationship of square under the constant opening angle. Moreover, the larger the opening angle of the two-stage flap valve is, the greater the relationship between hydraulic loss and flow is. Compared with the integral flap valve, the two-stage flap valve has better structural form and hydraulic characteristics, and has little influence on the performance of the pump device, which can provide reference for the application of the two-stage flap valve in the pump station.

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