scholarly journals Cavitating Vortex Flow Generated by a Stationary Volute Casing and a Rotating Centrifugal Impeller

2007 ◽  
Author(s):  
Tomoyoshi Okamura ◽  
Jun Kubota ◽  
Tatsuya Yoshikawa
Keyword(s):  
Vortex Flow ◽  
Solid Wall ◽  
Axial Flow ◽  
Centrifugal Impeller ◽  
Contaminated Water ◽  
Ideal Condition ◽  
Collision Chamber ◽  
Small Vortex ◽  
Strong Vortex ◽  
The Ideal

Three devices for treating contaminated water using a cavitating vortex have been developed and tested. The first device uses stationary twin volute casings to generate cavitating vortices. Observation of the collisions among the opposing counter-rotating vortices revealed that their end portions whirl, that the vortices never collide head-on, and that they eventually separate into several small vortex strings. The second device is simply half of the first device. A single volute casing is used, and the vortex flow collides with a solid wall. The third device uses a centrifugal impeller and a circular swirling chamber to generate a cavitating vortex. A high absolute circumferential velocity at the impeller exit induces a strong vortex in the chamber. The vortex cavitation is smoother than in the first two devices, and the end portion of the vortex whirls in the same manner as that generated in the first device. Installation of an orifice at the exit of the swirling chamber reduced the diameter of the flow passage and thereby accelerated the rotating and axial flow velocities. Testing showed that this third device produces fine, even-sized cavitation bubbles that are uniformly distributed in the collision chamber, which is the ideal condition for water treatment.

Improvement of Stalling Characteristics of an Axial-Flow Fan by Radial-Vaned Air-Separators

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Masayuki Ogata ◽  
Yohei Kato
Keyword(s):  
Solid Wall ◽  
Axial Flow ◽  
Internal Flow ◽  
Rotor Blades ◽  
Relative Location ◽  
Flow Conditions ◽  
Axial Flow Fan ◽  
Light Load ◽  
Stall Prevention ◽  
Air Separator

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.

Tip Leakage Flow Characteristics Downstream of an Axial Flow Fan

1996 ◽  
Author(s):  
P. Puddu
Keyword(s):  
Vortex Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Tip Leakage Flow ◽  
Single Wire ◽  
Vortex System ◽  
Tip Leakage ◽  
Stress Components ◽  
Computer Controlled

The three-dimensional viscous flow characteristics and the complex vortex system downstream of the rotor of an industrial exial fan have been determined by an experimental investigation using hot-wire anemometer. Single-wire slanted and straight type probes have been rotated about the probe axis using a computer controlled stepper motor. Measurements have been taken at four planes behind the blade trailing edge. The results show the characteristics of the relative flow as velocity components, secondary flow and kinetic energy defect. Turbulence intensity and Reynolds stress components in the leakage vortex area are also presented. The evolution of the leakage vortex flow during the decay process has also been evaluated in terms of dimension, position and intensity.

Approaching to the ideal condition of plasma confinement by applying external resonant fields in IR-T1 tokamak

2015 ◽  
Vol 81 (3) ◽  
Author(s):  
Sakineh Meshkani ◽  
Mahmood Ghoranneviss ◽  
Mansoureh Lafouti
Keyword(s):  
Magnetic Field ◽  
Turbulent Transport ◽  
Edge Plasma ◽  
Ideal Condition ◽  
Plasma Confinement ◽  
Applied Bias ◽  
Inverse Results ◽  
Electric And Magnetic Field ◽  
Helical Magnetic Field ◽  
The Ideal

For understanding the effect of resonant helical magnetic field (RHF) and bias on the edge plasma turbulent transport, the radial and poloidal electric field (Er, EP), poloidal and toroidal magnetic field (BP, Br) were detected by the Langmuir probe, magnetic probe and diamagnetic loop. The poloidal, toroidal and radial velocity (VP, Vr, Vt) can be determined from the electric and magnetic field. In the present work, we have investigated the effect of the magnitude of bias (Vbias = 200v, Vbias = 320v) on Er, EP, BP, Bt, VP, Vr, Vt. Moreover, we applied RHF with L = 2, L = 3 and L = 2 and 3 and investigate the effect of the helical windings radius on above parameters. Also, the experiment was repeated by applying the positive biasing potentials and RHF's simultaneously. The results show that by applying bias to the plasma at t = 15 msec at r/a = 0.9, Er, BP and Bt increase while EP decreases. The best modification occurs at Vbias = 200v. By applying RHF to the plasma, both the electric and magnetic field vary. Er reaches the highest in the presence of RHF with L = 3. The same results are obtained for BP, Bt, VP and Vt. While the inverse results are obtained for EP and Vr. Finally, RHF and bias are applied simultaneously to the plasma. With applied bias with Vbias = 200v and RHF with L = 2 and 3, we reach to the ideal circumstance. The same results obtain in the situation with Vbias = 320v and RHF with L = 2 and 3.

scholarly journals Energy Dissipation in Solid Roller Bucket and Controlled Stilling Basin for Ogee Stepped Spillway

2019 ◽  
Vol 8 (4) ◽  
pp. 2109-2112
Keyword(s):  
Energy Dissipation ◽  
Laboratory Experiments ◽  
Ideal Condition ◽  
Stepped Spillway ◽  
Type Ii ◽  
Dimensional Parameter ◽  
Stilling Basin ◽  
Sequent Depth ◽  
Tail Water ◽  
The Ideal

Hydraulic jump type II stilling basin is generally preferred as an energy dissipator for ogee spillway but it is uneconomical due to longer structure. On the other hand, roller bucket uses relatively shorter structure over a sloping apron or horizontal stilling basin. In this study, an attempt has been made to evaluate the performance of an ogee profile stepped spillway in combination with solid roller bucket and stilling basin type II for energy dissipation. Laboratory experiments are performed on a physical working model of ogee profile stepped spillway at discharge ranging from 0.0032 to 0.0069 m3 /s for a head of 1.5m, 4m & 7m and the results compared for energy dissipation (non-dimensional parameter (y c / h) = 0.69). The model results show that stepped spillway model without v-notch achieves 92.40 % energy dissipation. Thus this model is found to be more suitable to acquire the ideal condition of sequent depth and tail water depth in stilling basin for all the discharges.

scholarly journals Structural mitigation measures for flood reduction in urban area: A case study of Ciliwung watershed

2020 ◽  
Vol 200 ◽  
pp. 01004
Author(s):  
Rizki Maulana Fadillah ◽  
Hafizh Tsaqib ◽  
Aryanti Karlina Nurendyastuti ◽  
Miftahul Jannah ◽  
Rian Mantasa Salve Prastica
Keyword(s):  
River System ◽  
Mitigation Measures ◽  
Ideal Condition ◽  
Water Infrastructure ◽  
Embankment Dam ◽  
The Earth ◽  
Earth Embankment ◽  
Infrastructure Maintenance ◽  
The Ideal

Flooding is an obstacle for water infrastructure which installed in a river system in Ciliwung, West Java, Indonesia. The climate change triggers unpredictable rainfall which occurs in the watershed, therefore the vulnerability of river and other infrastructures are alarming. The rehabilitation and maintenance strategies are needed to make water infrastructures in the river system obtain lower damage. The research aims to simulate the 2-D HEC-RAS modelling of river system and stability. The result produces the water level of the river even in 1000-year discharge flood. Also, the research proposes the earth embankment dam for flood reduction in the watershed. The dam is designed according to the ideal condition. The simulation of HEC-RAS shows that the river experiences flooding in a certain condition. Besides, the research concludes that designed dam could overcome the flooding problem and suitable strategy for water infrastructure maintenance towards flooding impacts. Further investigation towards soil data for designed dam should be further analyzed to obtain better and comprehensive understanding.

Rekindling Hong Kong’s Magic

2017 ◽  
Author(s):  
Yue Chim Richard Wong
Keyword(s):  
Economic Growth ◽  
Health Care ◽  
Hong Kong ◽  
Regulatory Control ◽  
Public Expenditures ◽  
Ideal Condition ◽  
Political Landscape ◽  
Basic Law ◽  
Deficit Financing ◽  
The Ideal

Hong Kong’s divisive and fragmented political landscape provides the ideal condition for the proliferation of regulatory control. When the pressure on our government to spend more on housing, health care, and education is even greater than that in Singapore, and the Basic Law disallows deficit financing, then raising the regulatory burden is the only political solution available. Unfortunately, this will have far more damaging consequences on the economy. What is to be done? Can Hong Kong steer a path that allows it to fund the rising demand for public expenditures while promoting economic growth, so that the additional spending is economically affordable and politically feasible? That question will be addressed in this volume.

Flow Regimes in Two-Phase Hexane/Water Semibatch Vertical Taylor Vortex Flow

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Charlton Campbell ◽  
Michael G. Olsen ◽  
R. Dennis Vigil
Keyword(s):  
Vortex Flow ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Water Phase ◽  
Taylor Vortex ◽  
Two Phase ◽  
Annular Gap ◽  
Taylor Vortex Flow ◽  
Regime Map

Optical-based experiments were carried out using the immiscible pair of liquids hexane and water in a vertically oriented Taylor–Couette reactor operated in a semibatch mode. The dispersed droplet phase (hexane) was continually fed and removed from the reactor in a closed loop setup. The continuous water phase did not enter or exit the annular gap. Four distinct flow patterns were observed including (1) a pseudo-homogenous dispersion, (2) a weakly banded regime, (3) a horizontally banded dispersion, and (4) a helical flow regime. These flow patterns can be organized into a two-dimensional regime map using the azimuthal and axial Reynolds numbers as axes. In addition, the dispersed phase holdup was found to increase monotonically with both the azimuthal and axial Reynolds numbers. The experimental observations can be explained in the context of a competition between the buoyancy-driven axial flow of hexane droplets and the wall-driven vortex flow of the continuous water phase.

scholarly journals E-books for children with autism: Best read alone or with a therapist?

2020 ◽  
Vol 36 (1) ◽  
pp. 19-32
Author(s):  
Erin Soares ◽  
Therese Miller ◽  
Kathleen Ciffone ◽  
Kirsten Read
Keyword(s):  
Children With Autism ◽  
Autism Spectrum ◽  
Ideal Condition ◽  
Storybook Reading ◽  
Applied Behavioral Analysis ◽  
Story Reading ◽  
Children With Asd ◽  
Shared Storybook Reading ◽  
The Individual ◽  
The Ideal

Children with autism spectrum disorder (ASD) seemingly prefer tablets to other methods of intervention, though professionals posit that a therapist’s presence is beneficial. In this experiment, two unique e-stories were created specifically for children with ASD. Ten children with low- or nonverbal ASD heard each story presented on an iPad; one narrated through the iPad, and one read by a therapist trained in Applied Behavioral Analysis (ABA). The within-participants design enabled researchers to measure the individual benefit of each type of story reading. After hearing each book, participants were tested on their comprehension via multiple choice, sequencing, and open-ended questions. Results indicated that the ideal condition for these young children with low- and nonverbal ASD was the therapist-read condition. These findings suggest that simple stories presented on a rewarding platform, with the minimally intrusive assistance of a therapist, provide young, verbally-challenged children with ASD with a foundation for receiving the benefits of shared storybook reading.

Hydrodynamics of a droplet passing through a microfluidic T-junction

2017 ◽  
Vol 819 ◽  
pp. 401-434 ◽  
Author(s):  
Yongping Chen ◽  
Zilong Deng
Keyword(s):  
Vortex Flow ◽  
Flow Patterns ◽  
Lattice Boltzmann Model ◽  
Width Ratio ◽  
Droplet Deformation ◽  
Lubricating Film ◽  
Small Branch ◽  
Small Vortex ◽  
Break Up ◽  
Boltzmann Model

We develop a phase-field multiphase lattice Boltzmann model to systematically investigate the dynamic behaviour of a droplet passing through a microfluidic T-junction, especially focusing on the non-breakup of the droplet. Detailed information on the breakup and non-breakup is presented, together with the quantitative evolutions of driving and resistance forces as well as the droplet deformation characteristics involved. Through comparisons between cases of non-breakup and breakup, we find that the appearance of tunnels (the lubricating film between droplet and channel walls) provides a precondition for the final non-breakup of droplets, which slows down the droplet deformation rate and even induces non-breakup. The vortex flow formed inside droplets plays an important role in determining whether they break up or not. In particular, when the strength of vortex flow exceeds a critical value, a droplet can no longer break up. Additionally, more effort has been devoted to investigating the effects of viscosity ratio between disperse and continuous phases and width ratio between branch and main channels on droplet dynamic behaviours. It is found that a large droplet viscosity results in a small velocity gradient in a droplet, which restricts vortex generation and thus produces lower deformation resistance. Consequently, it is easier to break up a droplet with larger viscosity. Our work also reveals that a droplet in small branch channels tends to obstruct the channels and have small vortex flows, which induces easier breakup too. Eventually, several phase diagrams for droplet flow patterns are provided, and the corresponding power-law correlations ($l_{0}/w=\unicode[STIX]{x1D6FD}Ca^{b}$, where $l_{0}/w$ is dimensionless initial droplet length and $Ca$ is capillary number) are fitted to describe the boundaries between different flow patterns.

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