scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

Study on Magnetic Barrel Machine Equipped with Three-Dimensional Arrangement of Magnets

2007 ◽  
Vol 329 ◽  
pp. 761-766 ◽  
Author(s):  
Y. Zhang ◽  
Masato Yoshioka ◽  
Shin-Ichiro Hira
Keyword(s):  
High Speed ◽  
Permanent Magnets ◽  
Three Dimensional ◽  
Video Camera ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
The Media ◽  
Set Up

At present, a commercially available magnetic barrel machine equipped with permanent magnets has some faults arising from constructional reason. That is, grinding or finishing ability is different from place to place in the machining region, resulting in the limitation on the region we can use in the container of workpieces. Therefore, in this research, authors made the new magnetic barrel machine equipped with three dimensional (3D) magnet arrangement to overcome these faults. The grinding ability of the new 3D magnetic barrel machine converted was experimentally examined, and compared with that of the traditional magnetic barrel machine. As a result, it was shown that we can use much broader region in the new 3D machine. It was also shown that the grinding ability became higher. The distribution of barrel media in action was recorded by means of a high speed video camera. It was clarified that the media rose up higher and were distributed more uniformly in the container by the effect of the magnet block newly set up. It was supposed that this must be the reason for the above-mentioned improvement of grinding ability.

Numerical and Experimental Investigation of Secondary Flow in a High Speed Compressor Stator

1995 ◽  
Author(s):  
Y. Ohkita ◽  
H. Kodama ◽  
O. Nozaki ◽  
K. Kikuchi ◽  
A. Tamura
Keyword(s):  
Numerical Simulation ◽  
Experimental Investigation ◽  
Shear Flow ◽  
Secondary Flow ◽  
Total Pressure ◽  
High Speed ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Performance Recovery

A series of numerical and experimental studies have been conducted to understand the mechanism of loss generation in a high speed compressor stator with inlet radial shear flow over the span. In this study, numerical simulation is extensively used to investigate the complex three-dimensional flow in the cascades and to interpret the phenomena appeared in the high speed compressor tests. It has been shown that the inlet radial shear flow generated by upstream rotor had a significant influence on the stator secondary flow, and consequently on the total pressure loss. Redesign of the stator aiming at the reduction of loss by controlling secondary flow has been carried out and the resultant performance recovery was successfully demonstrated both numerically and experimentally.

Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes

2006 ◽  
Vol 3-4 ◽  
pp. 363-368 ◽  
Author(s):  
N. Temimi ◽  
Noelle Billon
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
Experimental Studies ◽  
Young Modulus ◽  
Video Camera ◽  
Image Correlation ◽  
Strain Rates ◽  
High Strain Rates ◽  
Low Velocity

Thermo mechanical behaviour of unfilled and filled polypropylenes are studied in tension from 10-4 to 102 s-1. Complementary low velocity compression and shear tests are also performed. A high-speed video camera (up to 2500 frames/s) combined with image analysis, image correlation and an infra red pyrometer allow measuring 3D-strain fields and temperature during tests. Thus, data can be processed without restrictive assumptions. Beside usual (for polymers) temperature and strain rate sensitivities it is found that plastic deformation in these materials does not obey incompressibility assumption. Voiding damage is evidenced in the polymer matrix by SEM observations that result in volume change and significant decrease in Young modulus for both materials. Moreover, an increase in the temperature of more than 10 °C is observed and is likely to modify the behaviour of each material at high strain rates. Shear and compression measurements demonstrate that yield criteria and constitutive equation depend on loading. It is concluded that apparent yield stress in semi-crystalline polypropylene can be a result of a combination of “non strain rate sensitive” “non-cohesive mechanisms” and “strain rate sensitive” “cohesive mechanisms”. Experimental characterisation on polymers should then be revisited as most of the usual assumptions are invalid and non monotonic tests should be generalized.

A Study of Aerodynamics Around Rotating Blades in a Lawnmower Deck

2002 ◽  
Author(s):  
P. A. Hagen ◽  
W. Chon ◽  
R. S. Amano
Keyword(s):  
High Speed ◽  
Flow Behavior ◽  
Video Camera ◽  
Element Analysis ◽  
Pressure Transducers ◽  
Discharge Velocity ◽  
Vapor Injection ◽  
High Speed Video Camera ◽  
Particle Feeding ◽  
Visualization Techniques

The objective of this study is to investigate the flow behavior within a triple-blade lawnmower deck. The test section was constructed for velocity measurement with an open bottom and side-discharge. Velocity measurements were collected at several different tangential and axial sections inside the deck. The flow behaviors are observed using Laser Doppler Velocimetry (LDV) and a high-speed video camera capturing 2000 frames per second. Several different visualization techniques have been attempted: particle feeding, water vapor injection, tuft method, and others. To further enhance the experimental accuracy, fresh sod was fed into the system simulating normal cutting conditions. Along with the extensive velocity analysis, strain and static pressure were also examined at various surface locations along the blade using linear strain gages, piezoresistive pressure transducers, and Finite Element Analysis (FEA) methods. Validation of the above analyses was performed using Computational Fluid Dynamics (CFD) investigation. It has been observed that the deck and blade configurations share equal significance in the resultant flow profiles.

scholarly journals Analysis of Hydrodynamics of Fluid Flow on Corrugated Sheets of Packing

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Kumar Subramanian ◽  
Günter Wozny
Keyword(s):  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Elementary Geometry ◽  
Ansys Fluent ◽  
Vof Model ◽  
Corrugated Sheets ◽  
Wetted Area ◽  
Icem Cfd ◽  
Good Agreement

Modelling of the hydrodynamics behaviour of the liquid on the corrugated sheets of packing is studied using three-dimensional, volume-of-fluid (VOF) model that is incorporated in Ansys Fluent 12.0. The flow of three different liquids with different physical properties is modelled. A domain of corrugated sheets of packing resembling the real structured packing with little modifications in the elementary geometry is constructed using ICEM CFD 12.0. The quantitative comparisons of the wetting behavior from the simulations are in good agreement with experiments. Further, the study has been extended to understand the influence of the second corrugated sheet on the flow behavior. The contours from the simulations indicate the liquid hold-up in the crimp of two corrugated sheets, and these results are in good agreement with the earlier experimental studies performed using X-ray tomography in the literature. The result from the simulation shows that even for the high flow rate of around 811 mL/min for silicon-oil (DC5), only 60% of the corrugated sheet has been wetted. Hence, the efficiency of the existing packing can be further increased by increasing the wetted area in the corrugated sheet of packing.

Experimental and Numerical Simulation on Hydraulic Behavior of Molten Flow in the Lower Part in Reactor Core

2016 ◽  
Author(s):  
Kota Matsuura ◽  
Hideaki Monji ◽  
Susumu Yamashita ◽  
Hiroyuki Yoshida
Keyword(s):  
Numerical Simulation ◽  
Liquid Film ◽  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Flow Behavior ◽  
Reactor Core ◽  
Video Camera ◽  
Working Fluid ◽  
Simulation Code

In the decommissioning work of nuclear power plants, it is important to grasp the sedimentation place of molten materials. However, the technique to grasp exactly sedimentation place is not established now. Therefore, the detailed and phenomenological numerical simulation code named JUPITER for predicting the molten core behavior is developed. In the study, visualization experiment and numerical simulation were performed to validate the applicability of the JUPITER to the hydraulic relocation behavior in core internals. The test section used in this experiment simulated the structure of the core internals, such as a control rod and a fuel support piece, simply. The working fluid is water under the atmospheric pressure. The experiment uses a high-speed video camera to visualize the flow behavior. The behavior and the speed of the liquid film in a narrow flow channel is obtained. For the numerical analysis carried out prior to the experiment, the behavior of flow down liquid was shown. The typical behavior was also observed that the tip of a liquid film flowing down splits into.

Improving Startup Behavior of Fluid Couplings Through Modification of Runner Geometry: Part I—Fluid Flow Analysis and Proposed Improvement

2000 ◽  
Vol 122 (4) ◽  
pp. 683-688 ◽  
Author(s):  
H. Huitenga ◽  
N. K. Mitra
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Operation Condition ◽  
Three Dimensional Flow ◽  
Economical Design ◽  
Hydrodynamic Coupling ◽  
Turbine Runner ◽  
Fluid Flow Analysis

For the use as a startup device the characteristic of a hydrodynamic coupling has to be steep at the nominal high speed operation condition and flat in the range of lower speed ratios. The economical design of the runner requires that the mass and the volume of the coupling should be as small as possible. The flow field in a starting configuration is simulated and a detailed analysis of the three-dimensional flow field is performed to deduce constructional modifications which meet both requests. The analysis shows that several modifications on pump and turbine runner seem to be successful. The consequences of the variation of the runner geometries will be discussed in detail in Part II of this paper. [S0098-2202(00)02104-0]

A High-Order LES Turbulent Model to Study Unsteady Flow Characteristics in a High Pressure Turbine Cascade

2008 ◽  
Author(s):  
Tomohiko Jimbo ◽  
Debasish Biswas ◽  
Yasuyuki Yokono ◽  
Yoshiki Niizeki
Keyword(s):  
Physical Process ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Measured Data ◽  
High Order ◽  
Turbulent Model ◽  
Loss Mechanism

In this work, unsteady viscous flow analysis around turbine blade cascade using a High-Order LES turbulent model is carried out to investigate basic physical process involved in the pressure loss mechanism. This numerical analysis is assessed to the wind tunnel cascade test. Basically, all the physical phenomena occurring in nature are the effect of some cause, and the effect can somehow be measured. However, to understand the cause, detail information regarding the visualization of the phenomena, which are difficult to measure, are necessary. Therefore, in our work, firstly the computed results are compared with the measured data, which are the final outcome of the cause (of the phenomena under investigation), to verify whether our physics-based model could qualitatively predict the measured facts or not. It was found that the present model could well predict measured data. Therefore, the rest of the computed information, which were difficult to measure, were used to visualize the overall flow behavior for acquiring some knowledge of the physical process associated with the pressure loss mechanism. Our study led to an understanding that the interaction of the vortex generated on the suction and pressure surface of the blade and the secondary vortex generated on the end-wall, downstream the trailing edge resulted in the formation of a large vortex structure in this region. This unsteady three-dimensional flow characteristic is expected to play an important role in the pressure loss mechanism.

scholarly journals The effects of forced small-wavelength, finite-bandwidth initial perturbations and miscibility on the turbulent Rayleigh–Taylor instability

2015 ◽  
Vol 787 ◽  
pp. 50-83 ◽  
Author(s):  
M. S. Roberts ◽  
J. W. Jacobs
Keyword(s):  
High Speed ◽  
Initial Perturbation ◽  
Mixing Layer ◽  
Experimental Studies ◽  
Growth Parameter ◽  
Video Camera ◽  
Taylor Instability ◽  
Layer Width ◽  
High Speed Video Camera ◽  
Rayleigh Taylor Instability

Rayleigh–Taylor instability experiments are performed using both immiscible and miscible incompressible liquid combinations having a relatively large Atwood number of $A\equiv ({\it\rho}_{2}-{\it\rho}_{1})/({\it\rho}_{2}+{\it\rho}_{1})=0.48$. The liquid-filled tank is attached to a test sled that is accelerated downwards along a vertical rail system using a system of weights and pulleys producing approximately $1g$ net acceleration. The tank is backlit and images are digitally recorded using a high-speed video camera. The experiments are either initiated with forced initial perturbations or are left unforced. The forced experiments have an initial perturbation imposed by vertically oscillating the liquid-filled tank to produce Faraday waves at the interface. The unforced experiments rely on random interfacial fluctuations, resulting from background noise, to seed the instability. The main focus of this study is to determine the effects of forced initial perturbations and the effects of miscibility on the growth parameter, ${\it\alpha}$. Measurements of the mixing-layer width, $h$, are acquired, from which ${\it\alpha}$ is determined. It is found that initial perturbations of the form used in this study do not affect measured ${\it\alpha}$ values. However, miscibility is observed to strongly affect ${\it\alpha}$, resulting in a factor of two reduction in its value, a finding not previously observed in past experiments. In addition, all measured ${\it\alpha}$ values are found to be smaller than those obtained in previous experimental studies.

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