A Design Basis for Vortex-Type Fluid Amplifiers Operating in the Incompressible Flow Regime

1970 ◽  
Vol 92 (2) ◽  
pp. 369-376 ◽  
Author(s):  
D. N. Wormley ◽  
H. H. Richardson
Keyword(s):  
Flow Regime ◽  
Incompressible Flow ◽  
Experimental Studies ◽  
Maximum Flow ◽  
Vortex Chamber ◽  
Control Flow ◽  
Port Area ◽  
Performance Specifications ◽  
Fluid Properties ◽  
Control Port

A rational procedure is developed for the design of a class of vortex amplifiers which operate in the incompressible flow regime. The procedure is based upon analytical and experimental studies conducted to determine the effects of fluid properties and geometry on vortex amplifier behavior. These studies indicate that the nondimensional amplifier characteristic is essentially independent of the maximum flow Reynolds number, vortex chamber height, and supply port area if each of these parameters is within a specified broad range of values. The nondimensional characteristic was found to depend fundamentally upon the chamber exit to outer periphery radius ratio and the control port area to exit port area ratio. A systematic method is provided for progressing from a set of desired amplifier performance specifications, which include maximum control and supply port pressure and flow requirements, to a specification of each critical amplifier dimension. Three-point predictions of the transfer characteristics are obtained and the characteristics are checked to determine if multiple values of total flow exist at the cutoff value of control flow. The measured performance of a planar vortex amplifier designed with the aid of the procedure was found to agree closely with the desired performance specifications.

Analysis and Modeling of the Vortex Amplifier

1969 ◽  
Vol 91 (4) ◽  
pp. 755-763 ◽  
Author(s):  
R. T. Bichara ◽  
P. A. Orner
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Computer Program ◽  
Flow Regime ◽  
Incompressible Flow ◽  
Digital Computer ◽  
Input Output ◽  
Critical Dimensions ◽  
Fluid Properties ◽  
Output Characteristics

A model has been derived to predict the steady-state input-output characteristics of vortex amplifiers operating in the incompressible flow regime. The model was correlated with experimental data to affect prediction of the influence of the operating fluid properties and the vortex valve critical dimensions on the valve characteristics. The model has been implemented in a digital computer program which includes procedures for the design of vortex valves with specified flow and pressure turndown ratios and the design of vortex amplifiers with proportional (single-valued) characteristics.

scholarly journals Switching Action of a Bistable Fluidic Amplifier for Ultrasonic Testing

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 171
Author(s):  
Thorge Schweitzer ◽  
Marla Hörmann ◽  
Benjamin Bühling ◽  
Bernhard Bobusch
Keyword(s):  
High Power ◽  
Ultrasonic Testing ◽  
Experimental Studies ◽  
Theoretical Background ◽  
Control Flow ◽  
Destructive Testing ◽  
Civil Infrastructures ◽  
Switching Action ◽  
Proportional Relationship ◽  
Control Port

Air-coupled ultrasonic testing is widely used in the industry for the non-destructive testing of compound materials. It provides a fast and efficient way to inspect large concrete civil infrastructures for damage that might lead to catastrophic failure. Due to the large penetration depths required for concrete structures, the use of traditional piezoelectric transducer requires high power electric systems. In this study, a novel fluidic transducer based on a bistable fluidic amplifier is investigated. Previous experiments have shown that the switching action of the device produces a high-power broadband ultrasonic signal. This study will provide further insight into the switching behaviour of the fluidic switch. Therefore, parametric CFD simulations based on compressible supersonic RANS simulations were performed, varying the inlet pressure and velocity profiles for the control flow. Switching times are analyzed with different methods, and it was found that these are mostly independent of the slope of the velocity profile at the control port. Furthermore, it was found that an inversely proportional relationship exists between flow velocity in the throat and the switching time. The results agree with the theoretical background established by experimental studies that can be found in the literature.

Numerical Study of an Ion Injection EHD Micropump

2009 ◽  
Author(s):  
R. Ghazi ◽  
M. S. Saidi ◽  
M. H. Saidi
Keyword(s):  
Numerical Investigation ◽  
Flow Rate ◽  
Incompressible Flow ◽  
Flow Model ◽  
Numerical Study ◽  
Maximum Flow ◽  
Back Flow ◽  
Ion Injection ◽  
Fluid Properties ◽  
Injection Type

The purpose of this study is to carry out a numerical investigation of injection type EHD pumps. To this end, the flow is considered laminar, steady and incompressible flow. The flow model is based on the assumptions that the fluid is Newtonian and the fluid properties are constant. The results show that all of the ions emitted from emitter are not collected by next collector electrode, but some of this injected ions move to the previous one, which causes back flow. Although this back flow is smaller than net pumping flow but it would reduce the net flow. Because of existence of this back flow, finding the optimum distance of electrodes from each other is necessary. This study shows that when the distance from emitter electrode to next collector is half of its distance from previous one, the maximum flow rate will be achieved. The results also show that flow rate reduces linearly as the pressure increases.

Scaling of the Hydroelastic Response of Flexible Lifting Bodies in Transitional and Turbulent Flows

2013 ◽  
Author(s):  
Antoine Ducoin ◽  
Yin Lu Young
Keyword(s):  
Turbulent Flows ◽  
Degrees Of Freedom ◽  
Experimental Studies ◽  
Full Scale ◽  
Stress Distributions ◽  
Viscous Effects ◽  
Scaling Methods ◽  
Fluid Properties ◽  
Computational Fluid Dynamics Cfd ◽  
Hydroelastic Response

The objective of this research is to derive and validate scaling relationships for flexible lifting bodies in transitional and turbulent flows. The motivation is to help the design and interpretation of reduced-scale experimental studies of flexible hydrofoils, with focus on the influence of viscous effects on the hydroelastic response. The numerical method is based on a previous validated viscous FSI solver presented in [1]. It is based on the coupling between a commercial Computational Fluid Dynamics (CFD) solver, CFX, and a simple two-degrees-of-freedom (2-DOF) system that simulates the free tip section displacement of a cantilevered, rectangular hydrofoil. To validate the scaling relations, sample numerical results are shown for three geometrically similar models: full scale, 1/2 scale and 1/10 scale. On the fluid side, although the effects of gravity and compressibility are assumed to be negligible, three different methods of scaling the velocity are considered: Reynolds scaling, Froude scaling, and Mach scaling. The three scaling methods produce different velocity scales when the fluid properties and gravitational constant are the same between the model and prototype, which will lead to different scaling for the material properties. The results suggest that by applying Mach scaling (which does not mean the flow is compressible, but simply requires the relative inflow velocity and fluid properties to be the same between the model and the prototype) and Re ≥ 2 × 106, the same material as the full scale could be used, which will lead to similar stress distributions, in addition to similar strains, and hence similar hydroelastic response and failure mechanisms. However, if Re ≤ 2 × 106 and Mach scale is used, a viscous correction is required to properly extrapolate the experimental results to full-scale.

scholarly journals Magneto-polar fluid flow through a porous medium of variable permeability in slip flow regime

2016 ◽  
Vol 21 (2) ◽  
pp. 323-339
Author(s):  
P.K. Gaur ◽  
A.K. Jha ◽  
R. Sharma
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Flow Regime ◽  
Slip Flow ◽  
Skin Friction Coefficient ◽  
Stream Velocity ◽  
Polar Fluid ◽  
Variable Permeability ◽  
Fluid Properties ◽  
Slip Flow Regime

Abstract A theoretical study is carried out to obtain an analytical solution of free convective heat transfer for the flow of a polar fluid through a porous medium with variable permeability bounded by a semi-infinite vertical plate in a slip flow regime. A uniform magnetic field acts perpendicular to the porous surface. The free stream velocity follows an exponentially decreasing small perturbation law. Using the approximate method the expressions for the velocity, microrotation, and temperature are obtained. Further, the results of the skin friction coefficient, the couple stress coefficient and the rate of heat transfer at the wall are presented with various values of fluid properties and flow conditions.

The maximum flow rate principle and vortex chamber aerodynamics

1989 ◽  
Vol 24 (3) ◽  
pp. 366-372 ◽  
Author(s):  
M. A. Gol'dshtik ◽  
A. V. Lebedev ◽  
M. Kh. Pravdina
Keyword(s):  
Flow Rate ◽  
Maximum Flow ◽  
Vortex Chamber ◽  
Maximum Flow Rate

A Review on Flow Regime Transition in Bubble Columns

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Ashfaq Shaikh ◽  
Muthanna H. Al-Dahhan
Keyword(s):  
Flow Regime ◽  
Bubble Column ◽  
Flow Behavior ◽  
Scale Up ◽  
Experimental Studies ◽  
Flow Regimes ◽  
Bubble Columns ◽  
Linear Stability Theory ◽  
Regime Transition ◽  
Flow Regime Transition

Due to varied flow behavior, the demarcation of hydrodynamic flow regimes is an important task in the design and scale-up of bubble column reactors. This article reviews most hydrodynamic studies performed for flow regime identification in bubble columns. It begins with a brief introduction to various flow regimes. The second section examines experimental methods for measurement of flow regime transition. A few experimental studies are presented in detail, followed by the effect of operating and design conditions on flow regime transition. A table summarizes the reported experimental studies, along with their operating and design conditions and significant conclusions. The next section deals with the current state of transition prediction, and includes purely empirical correlations, semi-empirical models, linear stability theory, and Computational Fluid Dynamics (CFD) based studies.

Numerical Investigation of Dynamic Characteristics of a Fluidic Device

2015 ◽  
Author(s):  
Bharat Koli ◽  
John W. Chew ◽  
Nick J. Hills ◽  
Timothy Scanlon
Keyword(s):  
Dynamic Characteristics ◽  
Control Flow ◽  
Low Flow ◽  
Flow State ◽  
Controlling Parameter ◽  
Fluidic Devices ◽  
Fluidic Device ◽  
Unsteady Interaction ◽  
Control Port ◽  
Cooling Air

Fluidic devices are of interest with turbomachinery internal air systems for modulation of cooling air and other applications. Generally, the flow states within a fluidic device are switched by control flow or flows. For most fluidic devices the switching procedure is almost instantaneous and hence it is difficult to characterize the performance of a device experimentally. The objective of this research is to numerically investigate the dynamic characteristics of a control flow operated fluidic device. In this study the dynamic characteristics of a nozzle during switching is considered. The simulations considered the unsteady interaction of the control flow with the nozzle jet for two different switching scenarios namely, switching of high to low flow state and vice versa. The magnitude of static pressure applied at the control port was identified as a controlling parameter and had to be below a critical value to achieve stable switching. The CFD solutions show that this is related to the flow physics and critical momentum flux ratios for switching are calculated for the present device.

Theoretical and experimental studies on vortex chamber flows

AIAA Journal ◽  
1986 ◽  
Vol 24 (4) ◽  
pp. 635-642 ◽  
Author(s):  
G. H. Vatistas ◽  
S. Lin ◽  
C. K. Kwok
Keyword(s):  
Experimental Studies ◽  
Vortex Chamber

Performance Effects of a Round Bar Passing Through the Outlet of a Vortex Amplifier

1991 ◽  
Vol 113 (4) ◽  
pp. 696-701
Author(s):  
K. Sato ◽  
N. Syred
Keyword(s):  
Heat Treatment ◽  
Swirling Flow ◽  
Flow Patterns ◽  
Vortex Chamber ◽  
Surface Heat ◽  
Control Flow ◽  
Water Model ◽  
Swirl Burner ◽  
High Heat Transfer ◽  
Round Bar

This paper considers the application of a vortex amplifier (VA) to the process of coating and surface heat treatment of a round bar. The advantage of using a vortex amplifier is not only a long maintenance free lifetime but also the ease with which the coating thickness or the heat treatment condition may be changed. Swirl burners offer many advantages in the surface heat treatment of round bars. The highly turbulent swirling flow generates uniform heat distribution and very high heat transfer coefficients which improve the quality of the surface being treated. The geometry of the swirl burner is such that very long bars may be treated using a relatively small burner, the bar being passed along the axis of the swirl burner. For coating applications, the round bar to be treated passes along the axis of the outlet of the vortex amplifier and the coating process is controlled by varying the control flow in the VA. Clearly the bar will have an effect on the performance. The effects of changing the diameter of the round bar are investigated. The effect of poor alignment of the round bar on the variations of supply pressure and control pressure is also considered. The flow patterns in the vortex chamber and the outlet were observed by means of cotton tufts. The internal flow patterns in the vortex chamber were observed using water model studies at a number of points on the vortex amplifier characteristic.

Sign in / Sign up

Export Citation Format

Share Document