Study on Micro Valve Using Micro Fluidic Device and Zero-Net-Flow-Rate Micro Jet

2007 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake
Keyword(s):  
Reynolds Number ◽  
Cross Section ◽  
Flow Rate ◽  
Piezoelectric Element ◽  
Test Fluid ◽  
Commercial Code ◽  
Fluidic Device ◽  
The Cross

Characteristics of a mini/micro-size Y-type fluidic device were examined using water as test fluid. The cross-section of an inlet path and outlet branches was 1 mm × 1 mm square. That of signal ports was 1 mm × 0.5 mm. Although Reynolds number tested was low; less than 1000, the mini/micro-size fluidic device functioned as the fluidic device; flow provided for a signal port flowed out from an opposite outlet. It was also analytically proved by the commercial code of STAR-CD. A zero-net flow micro-jet which had been analytically predicted was experimentally confirmed. A piezoelectric element was used to produce the zero-net flow micro-jet. A new concept of the mini/micro-size fluidic device was proposed. In that design, the signal ports were replaced with the zero-net flow micro-jet which was formed by the piezoelectric element. It was confirmed that the new design would function as the fluidic device.

Static and Dynamic Analysis of Aircraft Structures by Component-Wise Approach

2013 ◽  
Author(s):  
E. Carrera ◽  
A. Pagani ◽  
M. Petrolo
Keyword(s):  
Cross Section ◽  
Three Dimensional ◽  
Aircraft Structures ◽  
Static And Dynamic Analysis ◽  
Computational Costs ◽  
Commercial Code ◽  
Wing Structures ◽  
Order Of Magnitude ◽  
The Cross ◽  
Beam Theories

This paper proposes an advanced approach to the analysis of reinforced-shell aircraft structures. This approach, denoted as Component-Wise (CW), is developed by using the Carrera Unified Formulation (CUF). CUF is a hierarchical formulation allowing for the straightforward implementation of any-order one-dimensional (1D) beam theories. Lagrange-like polynomials are used to discretize the displacement field on the cross-section of each component of the structure. Depending on the geometrical and material characteristics of the component, the capabilities of the model can be enhanced and the computational costs can be kept low through smart discretization strategies. The global mathematical model of complex structures (e.g. wings or fuselages) is obtained by assembling each component model at the cross-section level. Next, a classical 1D finite element (FE) formulation is used to develop numerical applications. It is shown that MSC/PATRAN can be used as pre- and post-processor for the CW models, whereas MSC/NASTRAN DMAP alters can be used to solve both static and dynamic problems. A number of typical aeronautical structures are analyzed and CW results are compared to classical beam theories (Euler-Bernoulli and Timoshenko), refined models and classical solid/shell FE solutions from the commercial code MSC/NASTRAN. The results highlight the enhanced capabilities of the proposed formulation. In fact, the CW approach is clearly the natural tool to analyze wing structures, since it leads to results that can be only obtained through three-dimensional elasticity (solid) elements whose computational costs are at least one-order of magnitude higher than CW models.

Streamwise and Spanwise Flow Structures Over Backward Facing Step in Low Reynolds Number

2006 ◽  
Author(s):  
Shunsuke Yamada ◽  
Tatsuya Matsumoto ◽  
Takashi Nagumo ◽  
Shinji Honami
Keyword(s):  
Reynolds Number ◽  
Cross Section ◽  
Low Reynolds Number ◽  
Spanwise Direction ◽  
Streamwise Direction ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
The Cross ◽  
Low Reynolds

A study on the low Reynolds number flow such as the flow in or around the micro device is strongly required along with the development of the micro manufacturing technology. The low Reynolds number flow over a backward facing step is selected as one of the representative examples of the vortex dominant flows in the present study, because the mixing promotion is expected by an oscillatory motion of the vortex in the separating and reattaching shear layer over the step. It is important to clarify the flow fields in small channel or around the small device by flow visualization, since minimum disturbance in the measurement is achieved due to non-intrusive method. The objective of the present study is to clarify the flow behavior in the cross section in the spanwise, transverse and streamwise direction by the flow visualization using a high speed video camera. The Reynolds number based on the step height and the bulk velocity is set at 380 to 960. The visualization results in the cross section in the spanwise direction show that the separating shear layer from the step edge introduces a series of the primary vortices which have a rotation axis around the spanwise direction, and the main stream has a regularly whipping, wavy motion caused by the vortices moving toward the downstream direction along the upper and lower walls. The observation in the cross section in the transverse direction indicates that a scale of the vortex length in the streamwise direction is almost constant, but the primary vortex shows a periodic change in the spanwise direction, as the Reynolds number increases.

Resonance in Flow-Induced Cable Vibration: Analytical Prediction and Numerical Simulation

2005 ◽  
Author(s):  
M. K. Kwan ◽  
R. R. Hwang ◽  
C. T. Hsu
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Cross Section ◽  
Flow Direction ◽  
Cross Flow ◽  
Transverse Cross Section ◽  
Analytical Prediction ◽  
Water Flows ◽  
Flow Displacement ◽  
The Cross

Flow-induced resonance for a two-end hinged cable under uniform incoming flows is investigated using analytical prediction and numerical simulation. In this study, the fundamental mode is analyzed for simplicity. First, based on a series of physical judgments, the approximate cable trajectory is predicted — the whole cable vibrates as a standing wave, with its locus on the transverse cross-section having a convex “8”-like shape. To find the exact path, however, experiment or numerical simulation is necessary. Hence, a bronze cable at aspect ratio (length/diameter) of 100 under water flows at Reynolds number (based on cable diameter and incoming velocity) of 200 is computed. The result confirms our predictions. Moreover, it is found that the amplitude of the cross-flow displacement is much higher than that of the streamwise displacement, despite the higher streamwise fluid force. As a consequence, energy transfer from fluid to solid is maximized in the cross-flow direction.

scholarly journals Влияние числа Рейнольдса на распределение пульсационной составляющей вихря скорости по сечению плоского канала

2019 ◽  
Vol 89 (3) ◽  
pp. 347
Author(s):  
Ю.Г. Чесноков
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Cross Section ◽  
Liquid Flow ◽  
Direct Numerical Simulations ◽  
Mean Square ◽  
Flat Channel ◽  
Analysis Of Results ◽  
The Cross ◽  
Vortex Velocity

AbstractBased on the analysis of results from different authors using direct numerical simulations of the liquid flow in a flat channel, the effect of Reynolds number on the distribution of mean-square values of projections of a pulsed component of vortex velocity through the cross-section of a flat channel has been studied.

scholarly journals Effect of inertial lift on a spherical particle suspended in flow through a curved duct

2019 ◽  
Vol 875 ◽  
pp. 1-43 ◽  
Author(s):  
Brendan Harding ◽  
Yvonne M. Stokes ◽  
Andrea L. Bertozzi
Keyword(s):  
Reynolds Number ◽  
Spherical Particle ◽  
Cross Section ◽  
Bend Radius ◽  
Cross Sectional ◽  
Particle Reynolds Number ◽  
Curved Duct ◽  
Sectional Plane ◽  
Flow Through ◽  
The Cross

We develop a model of the forces on a spherical particle suspended in flow through a curved duct under the assumption that the particle Reynolds number is small. This extends an asymptotic model of inertial lift force previously developed to study inertial migration in straight ducts. Of particular interest is the existence and location of stable equilibria within the cross-sectional plane towards which particles migrate. The Navier–Stokes equations determine the hydrodynamic forces acting on a particle. A leading-order model of the forces within the cross-sectional plane is obtained through the use of a rotating coordinate system and a perturbation expansion in the particle Reynolds number of the disturbance flow. We predict the behaviour of neutrally buoyant particles at low flow rates and examine the variation in focusing position with respect to particle size and bend radius, independent of the flow rate. In this regime, the lateral focusing position of particles approximately collapses with respect to a dimensionless parameter dependent on three length scales: specifically, the particle radius, duct height and duct bend radius. Additionally, a trapezoidal-shaped cross-section is considered in order to demonstrate how changes in the cross-section design influence the dynamics of particles.

An Experimental Study of Heat Transfer and Pressure Drop on the Bend Surface of a U-Duct

2010 ◽  
Author(s):  
Tareq Salameh ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Cross Section ◽  
Outer Wall ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross

This work concerns an experimental study of pressure drop and heat transfer for turbulent flow inside a U-duct. Such duct geometries can be found in many engineering applications where cooling air extracts heat from hot internal walls of the duct, e.g., passage cooling inside gas turbine blades. Both friction factors and convective heat transfer coefficients were measured inside a U-duct for three different cases, namely (a) the smooth straight part, (b) the smooth bend (turn) part, and (c) a rough (ribbed) bend (turn) part. The details of the duct geometry were as follows: the cross section area of the straight part was 50×50 mm2, the inside length of the bend part 240 mm, the cross section area of the rib was 5×5 mm2 and the rib height-to-hydraulic diameter ratio, e/Dh, was 0.1. The Reynolds number was varied from 8,000 to 20,000. The test rig has been built in such a way that various experimental setups can be handled as the bend (turn) part of the U-duct can easily be removed and the rib configuration can be changed. Both the U-duct and the rib were made from plexiglass material to allow optical access for measuring the surface temperature by using a high-resolution measurement technique based on narrow band thermochromic liquid crystals (TLC R35C5W) and a CCD camera placed facing the bend (turn) part of the U-duct. The calibration of the TLC is based on the hue-based color decomposition system using an in-house designed calibration box. The rib was placed transversely to the direction of the main flow at the outer wall of the bend (turn) part where the wall was heated by an electrical heater. The friction factor ratio and the heat transfer enhancement ratio for case (c) at a Reynolds number of 20,000 were 48.75 and 2.66, respectively. It is found that the presence of the rib increases the heat transfer coefficient on the outer wall of the bend part (tip of side U-duct). The uncertainties were 3% and 6% for the Nusselt number and friction factor, respectively.

Component-Wise Method Applied to Vibration of Wing Structures

2013 ◽  
Vol 80 (4) ◽  
Author(s):  
E. Carrera ◽  
A. Pagani ◽  
M. Petrolo
Keyword(s):  
Cross Section ◽  
Eigenvalue Problems ◽  
Free Vibration Analysis ◽  
Computationally Efficient ◽  
Commercial Code ◽  
Wing Structures ◽  
Order Of Magnitude ◽  
The Cross ◽  
3D Elasticity ◽  
Reinforced Shell

This paper proposes advanced approaches to the free vibration analysis of reinforced-shell wing structures. These approaches exploit a hierarchical, one-dimensional (1D) formulation, which leads to accurate and computationally efficient finite element (FE) models. This formulation is based on the unified formulation (UF), which has been recently proposed by the first author and his coworkers. In the study presented in this paper, UF was used to model the displacement field above the cross-section of reinforced-shell wing structures. Taylor-like (TE) and Lagrange-like (LE) polynomial expansions were adopted above the cross-section. A classical 1D FE formulation along the wing's span was used to develop numerical applications. Particular attention was given to the component-wise (CW) models obtained by means of the LE formulation. According to the CW approach, each wing's component (i.e. spar caps, panels, webs, etc.) can be modeled by means of the same 1D formulation. It was shown that Msc/Patran® can be used as pre- and postprocessor for the CW models, whereas Msc/Nastran® DMAP alters can be used to solve the eigenvalue problems. A number of typical aeronautical structures were analyzed and CW results were compared to classical beam theories (Euler-Bernoulli and Timoshenko), refined models (TE) and classical solid/shell FE solutions from the commercial code Msc/Nastran®. The results highlight the enhanced capabilities of the proposed formulation. In fact, the CW approach is clearly the natural tool to analyze wing structures, since it leads to results that can only be obtained through 3D elasticity (solid) elements whose computational costs are at least one-order of magnitude higher than CW models.

scholarly journals Integral Thermo-Anemometers for Average Temperature and Airflow Measurement in Ducts, at Anemostat Outlets and in Ventilation Grilles

2020 ◽  
Vol 23 (4) ◽  
pp. 14-21
Author(s):  
Oleh S. Tsakanian ◽  
◽  
Serhii V. Koshel ◽  
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Air Flow ◽  
Hot Wire ◽  
Air Flow Rate ◽  
National Academy Of Sciences ◽  
Calibration Dependence ◽  
The Cross ◽  
And Control ◽  
Ventilation Systems

When creating ventilation systems, it is important to correctly calculate the volumes of air inflow and outflow. If an error is made in the calculation or a redistribution of air flows is required, measurements are indispensable. The existing methods for determining the air flow rate by using point measurements in the cross-section are laborious and time-consuming, and taking readings at different time points introduces a significant error into the result. A. M. Pidhornyi Institute of Mechanical Engineering Problems of the National Academy of Sciences of Ukraine has developed a new hot-wire anemometer whose use greatly simplifies the measuring process. This device allows one to measure the average values of temperature and air velocity (flow rate) in the cross-section of air ducts or at the inlets and outlets of grilles and anemostats, and can be used in real time to monitor and control air flow rate and temperature in ventilation systems. The probe of the hot-wire anemometer is a metal shell with guides on which a sensitive element is laid. Its principle of operation is to change the heat transfer coefficient at different air leakage velocities. The anemometer is preliminarily calibrated in laboratory conditions at various velocities. There has been obtained a calibration dependence that can be used to measure the air flow rate at the inlets and outlets of air distribution devices and directly in the air ducts. To improve the measurement accuracy, it is necessary to provide the 90° angle of airflow leakage on the hot-wire anemometer probe. For this, special air collectors and air flow rectifiers are used.

scholarly journals The criterion for turbulence in curved pipes

1929 ◽  
Vol 124 (794) ◽  
pp. 243-249 ◽  
Keyword(s):  
Reynolds Number ◽  
Cross Section ◽  
Small Hole ◽  
Stream Line ◽  
Straight Pipe ◽  
Curved Pipe ◽  
Curved Pipes ◽  
The Cross

Summary .—Experiments are described in which coloured fluid is introduced through a small hole in the side of a glass helix through which water is running. The conclusion reached by Mr. C. M. White, as a result of resistance measurements, that a higher speed of flow is necessary to maintain turbulence in a curved pipe than in a straight one, is verified directly. In a pipe bent into a helix the diameter of which was 18 times that of the cross-section, steady stream-line motion persisted up to a Reynolds number, 5830, i. e ., 2·8 times Reynolds' criterion for a straight pipe. This occurred in spite of the fact that the flow was highly turbulent on entering the helix.

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