Study of Particulate Flow in the Impeller of a Slurry Pump Using PIV

Volume 1 ◽  
2004 ◽  
Author(s):  
M. Mehta ◽  
J. R. Kadambi ◽  
S. Sastry ◽  
J. Sankovic ◽  
M. Wernet ◽  
...  
Keyword(s):  
Suction Side ◽  
Solid Particles ◽  
Working Fluid ◽  
Clear Fluid ◽  
Pump Speed ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Blade Tip ◽  
Particle Velocities

Particle Image Velocimetry (PIV) technique in conjunction with refractive index matching was successfully utilized to investigate the velocities of the slurry particles in the impeller of a centrifugal slurry pump. Tests were performed in an optically clear centrifugal slurry pump at speeds of 725 rpm and 1000 rpm using a slurry made up of sodium iodide solution as the working fluid and glass beads (500μm mean diameter) as solid particles at volumetric concentrations of 1%,2%, and 3%. In the intra blade region of the impeller, the highest particle velocities were obtained on the suction side of the blade and in the blade trailing edge region as the blade sweeps through and velocity magnitude increases with the pump speed. But this magnitude was less than that of circumferential velocity of the blade tip. Relative velocity plots show that flow separation takes place on the suction side of the blade in the region below the blade tip for clear fluid flow conditions. This was expected as the pump is made to operate with a slurry and not a single-phase liquid. At higher pump speeds and particle volumetric concentrations, a marked improvement in the slurry flow in the impeller is observed i.e., the recirculation zone decreases. This results from the centrifugal forces on the particles and its inertia at that speed. Also the slurry particles are pushed on the pressure side of the blade and slide along it which can result in frictional wear. These results are discussed in this paper.

Particle Velocities in the Rotating Impeller of a Slurry Pump

2007 ◽  
Author(s):  
M. Mehta ◽  
J. R. Kadambi ◽  
S. Sastry ◽  
J. M. Sankovic ◽  
M. P. Wernet ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Particle Velocity ◽  
Suction Side ◽  
Solid Particles ◽  
Working Fluid ◽  
Average Particle ◽  
Pump Speed ◽  
Velocity Magnitude ◽  
Refractive Index Matching ◽  
Particle Velocities

The velocities of the slurry particles in the impeller of a centrifugal slurry pump were obtained utilizing Particle image velocimetry (PIV) technique in conjunction with refractive index matching. Tests were performed in an optically clear centrifugal slurry pump at speeds of 725 rpm and 1000 rpm using a slurry made up of sodium iodide solution as a working fluid and glass beads (500μm mean diameter) as solid particles at volumetric concentrations of 1%, 2%, and 3%. In the intra blade region of the impeller, the highest particle velocities were obtained in the suction side of the blade and in the blade trailing edge region as the blade sweeps through and velocity magnitude increases with the increase in the pump speed. But this magnitude was less than that of circumferential velocity of the blade tip. The average particle velocities were obtained and it was found that the average particle velocity decreases with increase in concentration. The fluctuating component of particle velocity, which is related to the fluctuation kinetic energy were obtained. With the increase in the particle volumetric concentration, fluctuation kinetic energy decreases and the maximum fluctuation kinetic energy typically occurs on the suction side of the blade. The slurry particles are pushed on the pressure side of the blade and slide on it which can result in frictional wear. These results are discussed in this paper.

Particulate Velocity Measurements in the Intra-Blade Passages of a Centrifugal Slurry Pump

2003 ◽  
Author(s):  
J. R. Kadambi ◽  
M. Mehta ◽  
P. Charoenngam ◽  
M. P. Wernet ◽  
J. Sankovic ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Suction Side ◽  
Pressure Side ◽  
Pump Speed ◽  
Frictional Wear ◽  
Maximum Fluctuation ◽  
Blade Tip ◽  
Iodide Solution ◽  
Particle Velocities ◽  
Slurry Transport

The purpose of a slurry pump is to transport solids in a mixture called a slurry. It is a critical component of the slurry transport system in many industrial and mining related processes. In this investigation, Particle Image Velocimetry (PIV) was successfully utilized for measuring the particle velocities in the impeller intra-blade passages of an optically clear centrifugal pump (a transparent casing and a transparent three-blade impeller). An optically clear slurry consisting of sodium-iodide solution and 500 μm spherical glass particles was used. The experiments were conducted at speeds of 725 and 1000 rpm with volumetric concentrations of 2.5% and 5% respectively. In the impeller passage region, the highest particle velocities are generated on the suction side of the blade and in the blade trailing edge region as the blade sweeps through. However, these particle velocities are slower than the circumferential velocity of the blade tip. The particle fluctuation kinetic energy increased approximately 200% to 500% as the pump speed was increased from 725 rpm to 1000 rpm. The maximum fluctuation kinetic energy occurred on the suction side of the blade. The directional impingement mechanism is more significant at the pressure side of the blade. This mechanism becomes more pronounced as the speed increases. The random impingement mechanism caused by the fluctuation kinetic energy of the solids can play an important role on the blade surface (pressure and suction sides) and the casing wall erosion. Frictional wear mechanisms can be caused by the particles that do not stay suspended in the flow and accumulate into sliding beds along the pressure side of the blade. PIV measurements in the slurry pump model can add significantly to the understanding of the flow through the pump.

Experimental Characterization of Slug Flow Velocity Distribution in Two Phase Pipe Flow

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Velocity Distribution ◽  
Slug Flow ◽  
Two Phase ◽  
Significant Drop ◽  
Horizontal Pipe ◽  
Measured Velocity ◽  
Air Bubble ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching

This paper presents an experimental study of gas-liquid slug flow inside a horizontal pipe. The influence of air bubble passage on liquid flow is characterized using Particle Image Velocimetry (PIV) combined with Refractive Index Matching (RIM) and fluorescent tracers. A physical insight into the velocity distribution within slug flow is presented. It was observed that the slug flow significantly influences the velocity profile in the liquid film. Measured velocity distributions also revealed a significant drop in the velocity magnitude immediately upstream of the slug nose. These findings aim to aid an understanding of the mechanism of solid transportation in slug flows.

The Index Matching Method and its Application in V3V Measurements

2014 ◽  
Vol 1051 ◽  
pp. 946-950 ◽  
Author(s):  
Jian Gang Wang ◽  
Hua Lin Wang ◽  
Yi Fan ◽  
Yuan Huang
Keyword(s):  
Refractive Index ◽  
Measurement Accuracy ◽  
Particle Image ◽  
Solid Wall ◽  
Working Fluid ◽  
Refractive Indices ◽  
Matching Method ◽  
Index Matching ◽  
Refractive Index Matching

In imaging measurements on the fluid flow, the quality of particle image is essential to the outcomes of the velocity field. The method to eliminate the problems of refraction and reflection is to match the refractive indices of the working fluid and the surrounding solid wall. In this article, a comprehensive summary of the refractive index matching method was presented. Three fluid materials, two organic and one non-organic was used to conduct index matching and their effect were compared. Results show the perfect index matching is effective to improve the measurement accuracy of imaging measurements.

Influence of tip clearance and cavity depth on heat transfer in a cutback squealer tip

2020 ◽  
pp. 095441002096469
Author(s):  
Weijie Wang ◽  
Shaopeng Lu ◽  
Hongmei Jiang ◽  
Qiusheng Deng ◽  
Jinfang Teng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Suction Side ◽  
High Heat ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Cavity Depth ◽  
High Heat Transfer ◽  
Blade Tip ◽  
High Heat Transfer Coefficient

Numerical simulations are conducted to present the aerothermal performance of a turbine blade tip with cutback squealer rim. Two different tip clearance heights (0.5%, 1.0% of the blade span) and three different cavity depths (2.0%, 3.0%, and 6.0% of the blade span) are investigated. The results show that a high heat transfer coefficient (HTC) strip on the cavity floor appears near the suction side. It extends with the increase of tip clearance height and moves towards the suction side with the increase of cavity depth. The cutback region near the trailing edge has a high HTC value due to the flush of over-tip leakage flow. High HTC region shrinks to the trailing edge with the increase of cavity depth since there is more accumulated flow in the cavity for larger cavity depth. For small tip clearance cases, high HTC distribution appears on the pressure side rim. However, high HTC distribution is observed on suction side rim for large tip clearance height. This is mainly caused by the flow separation and reattachment on the squealer rims.

scholarly journals Refractive index matching applied to fecal smear clearing

2005 ◽  
Vol 47 (6) ◽  
pp. 347-350 ◽  
Author(s):  
Cláudio S. Ferreira
Keyword(s):  
Refractive Index ◽  
Sucrose Solution ◽  
Glycerol Solution ◽  
Human Feces ◽  
Microscope Slide ◽  
Helminth Eggs ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Fecal Smear ◽  
Effect Of Light

Thick smears of human feces can be made adequate for identification of helminth eggs by means of refractive index matching. Although this effect can be obtained by simply spreading a fleck of feces on a microscope slide, a glycerol solution has been routinely used to this end. Aiming at practicability, a new quantitative technique has been developed. To enhance both sharpness and contrast of the images, a sucrose solution (refractive index = 1.49) is used, which reduces the effect of light-scattering particulates. To each slide a template-measured (38.5 mm³) fecal sample is transferred. Thus, egg counts and sensitivity evaluations are easily made.

Preliminary Investigation on the Effect of the Modification of the Sweep Angle at the Blade Tip of Forward Swept Axial Fans

2017 ◽  
Author(s):  
Massimo Masi ◽  
Andrea Lazzaretto
Keyword(s):  
Preliminary Investigation ◽  
Suction Side ◽  
The Other ◽  
Axial Fan ◽  
Sweep Angle ◽  
End Effects ◽  
Flow Rates ◽  
Stall Margin ◽  
Other Hand ◽  
Blade Tip

The flow path close to the suction side of fan rotor blades mostly affects the overall drag of the blading. The blade lift is affected as well because of the separation of the low energy boundary layer that drives the blade into stall at low fan flow rates. Forward sweep allows to position the airfoil sections of blades featuring a positive circulation gradient along the span so that they “accompany” the near-wall flow trajectories at the blade suction side. So, rotor efficiency and stall margin of the fan can be improved. On the other hand, blade end effects play a relevant role in high hub-to-tip and low aspect ratio rotors and may compromise the effectiveness of forward sweep. Nevertheless, some authors in the literature stated the beneficial contribution of changing the sweep angle at the ends of the blade both at design and off-design conditions. The paper studies the end effects on constant-swirl design rotors by means of CFD simulations focusing on the distribution of blade sweep in the near-tip region. In particular, the performance and efficiency calculated for a forward swept tube-axial fan featuring a hub-to-tip ratio equal to 0.4 are compared with those estimated for the corresponding unswept fan at equal duty point. Several modifications of the sweep distribution in the blade tip region are considered in the swept fan to quantify their effect on performance, efficiency and stall margin. Results show that the addition of up to 6 degrees of local forward sweep at the blade tip to the unswept blading does not affect fan pressure at design operation. On the other hand, this local increase of the sweep angle allows for a very notable increase of the peak pressure and efficiency at flow rates close to stall inception.

scholarly journals Biological glass: structural determinants of eye lens transparency

2011 ◽  
Vol 366 (1568) ◽  
pp. 1250-1264 ◽  
Author(s):  
Steven Bassnett ◽  
Yanrong Shi ◽  
Gijs F. J. M. Vrensen
Keyword(s):  
Refractive Index ◽  
Cellular Level ◽  
Structural Determinants ◽  
Lens Transparency ◽  
Index Matching ◽  
Lens Fibre ◽  
Refractive Index Matching ◽  
Lens Membranes ◽  
Adhesive Proteins ◽  
Structural Adaptations

The purpose of the lens is to project a sharply focused, undistorted image of the visual surround onto the neural retina. The first pre-requisite, therefore, is that the tissue should be transparent. Despite the presence of remarkably high levels of protein, the lens cytosol remains transparent as a result of short-range-order interactions between the proteins. At a cellular level, the programmed elimination of nuclei and other light-scattering organelles from cells located within the pupillary space contributes directly to tissue transparency. Scattering at the cell borders is minimized by the close apposition of lens fibre cells facilitated by a plethora of adhesive proteins, some expressed only in the lens. Similarly, refractive index matching between lens membranes and cytosol is believed to minimize scatter. Refractive index matching between the cytoplasm of adjacent cells is achieved through the formation of cellular fusions that allow the intermingling of proteins. Together, these structural adaptations serve to minimize light scatter and enable this living, cellular structure to function as ‘biological glass’.

Sign in / Sign up

Export Citation Format

Share Document