scholarly journals Novel analysis for large strains based on particle image velocimetry

2017 ◽  
Vol 54 (7) ◽  
pp. 933-944 ◽  
Author(s):  
Núria M. Pinyol ◽  
Mauricio Alvarado
Keyword(s):  
Particle Image Velocimetry ◽  
Slope Failure ◽  
Particle Image ◽  
Large Strains ◽  
Software Packages ◽  
Piv Technique ◽  
Standard Procedures ◽  
Image Velocimetry ◽  
Sandy Slope ◽  
Piv Analysis

Over the last few decades, the particle image velocimetry (PIV) technique has become an interesting tool used to measure displacements in the field of experimental mechanics. This paper presents a procedure to interpret PIV displacements, measured following an Eulerian scheme, with the purpose of providing accumulated displacements, velocities, accelerations, and strains on points representing physical particles. Strains are computed as the gradient of displacements. When compared with other standard procedures already published, the presented methodology is especially well suited to interpret large strains. The basis of the procedure is to map displacement increments measured through PIV analysis on the subset (or patch) centres into numerical particles that are defined as portions of the moving masses whose deformation is analyzed. The implementation of the method is explained in detail, highlighting its simplicity. The procedure can be used as a post-processor of currently available PIV software packages. The methodology is first applied to synthetic cases of rectangular samples in which known displacements are imposed and also to a sandy slope failure experiment involving large displacements. The method reproduces satisfactorily the recorded images.

Effect of inlet port on the flow in the cylinder of an internal combustion engine

2006 ◽  
Vol 220 (1) ◽  
pp. 73-82 ◽  
Author(s):  
A Yasar ◽  
B Sahin ◽  
H Akilli ◽  
K Aydin
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Distribution ◽  
Particle Image ◽  
Combustion Engine ◽  
Flow Characteristics ◽  
Intake Port ◽  
Intake Valve ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Image Density

In this study, the characteristics of flow emerging from the inlet of the intake port in the cylinder were investigated experimentally. A particle image velocimetry (PIV) technique was used to measure the velocity distribution in order to observe and analyse the flow behaviour. High-image-density PIV provided acquisition of patterns of instantaneous and averaged vorticity and velocity, revealing the detail of the flow characteristics in the cylinder cavity. With this measuring technique, it is possible to study the effect of intake valve geometry on the flow behaviours. The results showed that the flow structure changed substantially along the cylinder stroke due to the geometry of the intake valve port.

Characteristics of Turbulent Flows Over Forward Facing Steps in Adverse Pressure Gradients Based on Two-Point Analyses

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Hassan Iftekhar ◽  
Martin Agelin-Chaab
Keyword(s):  
Particle Image Velocimetry ◽  
Turbulent Flows ◽  
Coherent Structures ◽  
Particle Image ◽  
Adverse Pressure Gradient ◽  
Pressure Gradients ◽  
Physical Size ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Point Velocity

This study reports the results of turbulent flows forward facing steps (FFS) in pressure gradients using a particle image velocimetry (PIV) technique to obtain data up to 68 step heights downstream. The contours of two-point velocity correlations indicate that regardless of the pressure gradients, the physical size of the coherent structures characterized by the autocorrelations grows as the flow develops downstream along the step. Additionally, adverse pressure gradient (APG) elevates the size of the autocorrelations.

Study on Improvement of the Suction Valve Using PIV Technique

2005 ◽  
Author(s):  
Eitaro Koyabu ◽  
Tetsuhiro Tsukiji ◽  
Yoshito Matsumura ◽  
Taizo Sato
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Vibration Reduction ◽  
Flow Analysis ◽  
Particle Image Velocimetry System ◽  
Test Model ◽  
Reciprocating Compressor ◽  
Air Conditioner ◽  
Piv Technique ◽  
Image Velocimetry

The simplified test model of the commercial reciprocating compressor for an automotive air-conditioner is used to measure the displacement of the suction valves using a strain gauge and to investigate the velocity distributions of the discharge flow from the valves using the particle image velocimetry system. This paper is focused on the effects of shape of the suction valve on the vibration-reduction. The size of the suction valve hole and the width of the tip of the suction valve are changed as main parameters of the valve shape. First, the size of the conventional valve hole and the width of the tip of the conventional valve are changed and seven new valves are manufactured to reduce the vibration of the valve. Consequently, it is found that one shape of the new valves is the most effective for the vibration-reduction. Next, the influence of the natural frequency on the vibration-reduction is investigated using one shape of the new valves by changing the material and the thickness of the valve. In addition, the relation between the conventional valve and the new valves are also estimated by the pressure loss. Finally, the reason of the vibration-reduction for one shape of the new valves is discussed from the results of the flow analysis around the valve. The vibration-reduction for one shape of the new valves is confirmed by measurement of the displacement of the valve in the reciprocating compressor for the automotive air-conditioner.

In-Cylinder Fuel-Air Mixture Investigation by Particle Image Velocimetry in a GDI Engine

2004 ◽  
Author(s):  
G. Valentino ◽  
M. Auriemma ◽  
G. Caputo ◽  
F. E. Corcione
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Rate ◽  
Particle Image ◽  
Direct Injection ◽  
Air Flow ◽  
Piv Technique ◽  
Fuel Jet ◽  
Image Velocimetry ◽  
Gdi Engine ◽  
Intake Flow

The present paper aims at providing experimental results on the spray structure and its interaction with the air flow generated by the intake ducts of a commercial light duty gasoline direct injection (GDI) engine head. The investigation was carried out by the Particle Image Velocimetry (PIV) technique to investigate the air flow and fuel droplets velocity evolution within a prototype cylinder with optical accesses. Experiments were carried out at various operating conditions reproducing the mixture preparation for an early injection strategy. The PIV technique was applied in a flow test rig assembled with a blower, which supplied the intake flow rate, connected to the intake manifold of a commercial 4-valve direct injection gasoline engine head modified to lay down an external driving control system for the valves motion. Experiments were taken equipping the engine head with a common rail injection system able to work up to 10 MPa, and a swirled type injector having a nozzle diameter of 0.50 mm and a nominal cone angle of 60°. Tests were taken, on a plane crossing the cylinder and the injector axes, supplying to the prototype cylinder an intake flow rate of 29 m3/h and spraying the gasoline at two injection timings in a range of injection pressure of 6, 8, and 10 MPa. The results provided detailed information on the intake flow field behavior and the evolution of fuel jet within the air flow. The intake flow velocity distribution, acquired at different cam angle during the induction, showed the development of an initial clockwise tumble flow with a tendency to produce two large flow structures: a main counter clockwise vortex and a clockwise ones located at the opposite side of the field of view. Images of the interaction of the fuel with the tumble motion displayed, firstly, a fuel jet shape that traveled not affected by the tumble motion because of its high momentum. Later during the intake, the fuel was strongly distorted by the air motion with the formation of clusters detached from the main jet and spread within the cylinder so allowing to hypothesize that the intake bulk flow may be a crucial parameter to control the fuel penetration and the droplets distribution within the cylinder.

The Influence of Boundary Condition on Solidification of Binary Solution in Rectangular Cavity

1999 ◽  
Author(s):  
N. Pradeep ◽  
H. J. Kang ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Binary Solution ◽  
Solidification Process ◽  
Heat Transfer Process ◽  
Bottom Surface ◽  
Piv Technique ◽  
Image Velocimetry

Abstract The solidification of a binary mixture of ammonium chloride and water flow cooling in rectangular cavities was investigated experimentally under different boundary conditions. Two cavities measuring 63.5 × 180 × 165 mm and 76 × 120 × 96 mm were employed in this study. For the first cavity, its three surfaces (i.e., two side surfaces and one bottom surface) were cooled. For the second cavity, however, only two side surfaces were cooled (i.e., the bottom surface was adiabatic). The influence of the change of boundary was studied. All investigations were carried out in the surface temperature range from −15 to −30°C under a constant refrigerant temperature of −22°C. The effect of cooling boundary condition had a great effect on the heat transfer process during the solidification process. The advanced Particle Image Velocimetry (PIV) technique was used to catch the velocity profiles during the solidification process.

PIV Analysis of Instantaneous Flow Structures in an Inkjet Printhead

1999 ◽  
Author(s):  
Hongsheng Zhang ◽  
Carl D. Meinhart
Keyword(s):  
Particle Image ◽  
Fluid Velocity ◽  
Ccd Camera ◽  
Velocity Fields ◽  
Flow Structures ◽  
Instantaneous Flow ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Piv Analysis ◽  
Inkjet Printhead

Abstract This paper presents experimental measurements and observations of instantaneous flow structures inside an inkjet printhead, using a micron-resolution Particle Image Velocimetry (PIV) system to record visualized flows and calculate velocity fields. The PIV technique uses 700 nm diameter fluorescent flow-tracing particles, a pulsed Nd:YAG laser, an epi-fluorescent microscope and an interline-transfer CCD camera to record images of a flow at two successive instances in time. By measuring how far a set of particles move during a specified duration of time, an estimate of the local fluid velocity can be obtained. An electronic timing strategy has been developed to synchronize the PIV lasers, the CCD camera and the drop ejection system. An overall flow pattern during a 500 μs ejection cycle has been observed by phase-averaging hundreds of instantaneous velocity fields, which were recorded at 2–5 μs intervals throughout the cycle. A velocity field with spatial resolution of approximately 10 μm was obtained near the inkjet nozzle. Meniscus and nodes inside the printhead were also observed and recorded.

Downstream particle image velocimetry measurements of a circular cylinder—plate junction

2009 ◽  
Vol 223 (8) ◽  
pp. 1837-1849 ◽  
Author(s):  
N A Ozturk ◽  
A Akcayoglu ◽  
B Sahin
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Particle Image ◽  
Flow Characteristics ◽  
Horseshoe Vortex ◽  
Shear Layers ◽  
Wake Flow ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Series Of Experiments

In the present investigation, special attention was given to the flow characteristics downstream of a circular cylinder mounted on a flat surface for Reynolds numbers of 4000 and 7000. A series of experiments were performed in successive end-view planes with the range of 0≤ XL/ d≤5 using the particle image velocimetry (PIV) technique in order to demonstrate characteristics of wake flow structure and interactions between the shear layers caused by shedding vortices and tails of the horseshoe vortex system emanating from the upstream base of the cylinder. The development and growth of primary vortices in the end-view planes caused by the interactions of core flow and wake flow regions along the inner face of the shedding shear layers were examined quantitatively. Finally, it was concluded that the PIV technique was also capable of providing accurate velocity readings in the end-view planes of the wake flow regions.

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