bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Analysis and Design Suggestions for Regenerative Flow Pumps (Keynote)
Authors: Engeda Abraham
Published: February 2009

The Regenerative Flow Pump, here referred to as RFP is a turbomachine capable of developing high pressure ratios in a single stage. It is also known with other names such as: • Peripheral pump; • Side channel pump; • Turbine pump; • Drag pump; • Traction pump; • Vortex pump. This paper reviews the status of the RFP and proposes a design guideline, with the aim to improve the performance and efficiency of the RFP. All previous works concentrated on the fully-developed flow region in the RFP and this work expands the consideration to the developing region.
Development of a Maritime Current Turbine
Authors: Ruprecht Albert , Reinhardt Holger
Published: February 2009

Maritime currents show a high potential for electricity generation. Consequently there are many projects for their exploitation. Here the development of a maritime current turbine is shown. A shrouded propeller turbine has been chosen. The design of the propeller as well as the design of the shroud are discussed. The turbine has been developed with fixed, not adjustable blades and with variable speed operation. For the propeller the robustness has been emphasized against the peak efficiency. The design goal for the shroud has been to find a very compact shape without loosing much of the performance in order to reduce the production costs.
Effect of Reynolds Number on Performance of a Small Centrifugal Pump
Authors: Day Steven W. , Lemire Phillip P. , Flack Ronald D. , McDaniel James C.
Published: February 2009

A study of a small centrifugal blood pump has been made to address the effectiveness of traditional pump affinity laws and the influence that viscous effects, as characterized by the Reynolds number, have on the pump performance. This was investigated both experimentally and numerically on models of a small implantable centrifugal blood pump, which has an impeller diameter of 46 mm with a log spiral volute. In the experiments, the Head-Flow curves were determined for speeds between 500 and 3000 rpm and for two different viscosity fluids. It was found that lower Reynolds number flows did not adhere to conventional pump affinity laws, whereas higher Reynolds number flows scale very effectively according to pump affinity laws. The numerical study consisted of comparing the generated head and internal flow field of the pump scaled based on traditional affinity laws with and without consideration of the Reynolds number. Like the experimental results, the numerical simulations indicate that consideration of the Reynolds number is necessary to insure accurate scaling in this small pump.
Propulsion System Requirements for Quiet, Long Range, Supersonic Aircraft
Authors: Brear Michael J. , Kerrebrock Jack L. , Epstein Alan H.
Published: February 2009

This paper discusses the requirements for the propulsion system of supersonic cruise aircraft that are quiet enough to fly over land and operate from civil airports, have trans-pacific range in the order of 6000 nmi (11,112 km), and payload in the order of 10,000 lb (4,545 kg). It is concluded that the resulting requirements for both the fuel consumption and engine thrust/weight ratio for such aircraft will require high compressor exit and turbine inlet temperatures, together with bypass ratios that are significantly higher than typical supersonic-capable engines. Several technologies for improving both the fuel consumption and weight of the propulsion system are suggested. Some of these directly reduce engine weight whilst others, by improving individual component performance, will enable higher bypass ratios. The latter should therefore also indirectly reduce the bare engine weight. It is emphasized, however, that these specific technologies require considerable further development. Whilst the use of higher bypass ratio is a significant departure from more usual engines designed for supersonic cruise, it is nonetheless considered to be a practical option for an aircraft of this kind.
Flow and Chemical Kinetics Simulations of Endothermic Fuels
Authors: Ward Thomas A. , Ervin Jamie S. , Striebich Richard C. , Zabarnick Steven
Published: February 2009

Advanced aircraft engines are reaching a practical heat transfer limit beyond which the convective heat transfer provided by hydrocarbon fuels is no longer adequate. One solution is to use an endothermic fuel that absorbs heat through chemical reactions. This paper describes the development of a two-dimensional computational model of the heat and mass transport associated with a flowing fuel using a unique global chemical kinetics model. Most past models do not account for changes in the chemical composition of a flowing fuel and also do not adequately predict flow properties in the supercritical regime. The two-dimensional computational model presented here calculates the changing flow properties of a supercritical reacting fuel by use of experimentally derived proportional product distributions. The present calculations are validated by measured experimental data obtained from a flow reactor of mildly cracked n-decane. It is believed that these simulations will assist the fundamental understanding of high temperature fuel flow experiments.
Aerodynamic Loads Prediction in an Integrated Computer-Based Conceptual Design Environment
Authors: Goldstraw M. W. , Bil C. , Nicholson C.
Published: February 2009

An important aspect of successful aircraft design is the concept of ‘right first time’, as any design changes downstream can be costly and may cause project delays. This is most applicable to the conceptual design phase. However, in the early stages of aircraft design, data is limited and prone to inaccuracies. Consequently, a design will typically traverse through a number of iterations, improving and refining with each step. Over the past 15 years, computer-based tools have become commonplace in aircraft design [1]. In general, most computer-based tools have been developed for the more advanced stages of the design process. For these tools to be useful in conceptual design, they must be user-friendly, interactive, and provide quick return times. A classic example is the aerodynamic load data required for structural design. Both are dependent on geometric parameters, which may still be subject to change. To complete the analysis within practical time constraints, a highly integrated and automated system is required [2, 3]. This paper presents such a system, developed using industry accepted software components including AutoCAD, VSAERO and MSC Nastran. This system allows an automatic, structured topology mesh to be generated from a basic three-view aircraft drawing, which inputs directly into VSAERO for loads calculations. The loads are subsequently transferred to MSC Patran as a pre-processor for structural analysis using MSC Nastran. If the result is unsatisfactory, the geometry or placement of structural components can easily be changed and the process repeated. The design environment was developed using FORTRAN90. The results of an application of this system to a simple wing, as well as a regional transport aircraft, are also presented.
Non-Contact Measurement of Thermophysical Properties of Liquids by Acoustic and Electrostatic Levitation
Authors: Sadhal S. S. , Ohsaka K. , Rednikov A. Y.
Published: February 2009

The thermodynamic behavior of liquids in undercooled states is an area that has gained considerable importance in various applications. In nature, as well as with industrial situations such as liquid-metal spray deposition, liquid states are found to exist below the freezing point, especially if a pure liquid remains in a relatively undisturbed state. Since a disturbance can easily disrupt the undercooled state, measurements need to be carried out non-intrusively. Furthermore, the liquid sample has to be held without a container since most solid containers would promote heterogeneous nucleation at the freezing point. Therefore, electrostatic and acoustic levitation techniques are being employed. The measurement of viscosity and surface tension are being conducted by observing the response of initially deformed drops (acoustically and electrostatically) to more spherical shapes upon relaxation of the deforming force fields. The measurement of properties, such as thermal diffusivity, are conducted by the application of a thermal stimulus to a levitated liquid sample and the observation of the response from which such properties can be inferred. The effect of buoyancy-driven convection is suppressed by horizontally flattening the drop with an acoustic field, thus leaving a small gravitational force potential. This approach has been found to effectively reduce the flow to a thermoacapillary dominant type, accompanied by acoustic disturbances. This lends itself to measurements of the thermocapillary flows with minimal buoyancy interference even in a unit-gravity field.
Analyses of Hydrodynamic Structure of Water Jet and Its Application to Jet Grouting
Authors: Yoshida Kenji , Kataoka Isao , Yoshida Hiroshi , Yokoo Mitsuru , Horii Kiyoshi
Published: February 2009

Analyses of water jet based on two-fluid model of two-phase dispersed flow have been carried out for single water jet and cross water jet in relation to the water jet technology in civil engineering. Mass and momentum conservation equations for liquid phase (droplet) gas phase (air) were formulated separately (two-fluid model formulation). Physical modeling of diffusion of droplets, drag coefficient of droplet in dispersed flow, shear stress at jet interface, etc has been carried out in detail and constitutive equations for these physical phenomena have been developed. Based on the two-fluid model basic equations and constitutive equations, one-dimensional analysis has been carried out considering simplified model. In the practical application of present analyses, some preliminary analyses on cross jet where two water jets collide with certain collision angles have been carried out and the predicted results reasonably explain the experimental results.
A New Utilization System of Light-Weighted Landfill Materials Produced From High Water-Content Mud
Authors: Takahashi Hiroshi , Mori Masato , Horii Kiyoshi , Ousaka Akiharu , Kotani Kenji , Naganuma Takashi
Published: February 2009

A new recycling system by using paper debris and polymer has been developed for high water-content mud such as bed materials in the river and lake, and construction sludge. The new recycling system proposed in this study consists of two steps. In the first step, the paper debris are added for controlling water content of mud and strengthening the bonding force between mud clusters. In the second step, polymer materials are added to increase the bonding force of mud particles in the cluster. By using this system, 200–500% water-content mud has been modified to landfill materials by 20–30 minutes mixing process. The modified soils have several features and one of the features of modified soils is “light-weighted”. In this study, a theoretical equation to estimate the density of modified soils is derived. By using this equation, a design system to use light-weighted landfill materials is proposed.
Transient Numerical Simulation of Non-Isothermal Process of RTM
Authors: Shahnazari M. R. , Abbassi A.
Published: February 2009

In this paper, based on a physical model the resin transfer moulding (RTM) of a non-isothermal process has been simulated. It is assumed that the flow in porous medium is under the Darcian regime. Also, the relationship between flow mean velocity in each section has been considered in terms of porosity. The governing equations including heat dispersion term are solved numerically. To verify the model results, the temperature profiles for two types of fibers have been calculated, and are compared with experimental results of other researchers. The results showed that, to optimize the better quality of production of composite materials, the importance of heat dispersion term can not be neglected.
Swirling Flow Effect on Mixing Performance of Excavated Soils and Additives in Soil-Recycling Machine
Authors: Takahashi Hiroshi , Sekino Satoshi , Hashimoto Hisayoshi
Published: February 2009

Recently, an excavated soil-recycling machine has been receiving considerable attentions. The mobile type excavated soil-recycling machine is able to improve the soils by adding the additives such as slaked lime and cement at the construction site. However, not only the mechanical factors such as paddle inclination angle and pitch of the paddle but also the physical properties of the excavated soils affect the mixing performance of the excavated soils and additives. In this sense, experimental investigations are uneconomical and ineffective. This paper concerns with the numerical simulator to analyze the mixing behavior of excavated soils and additives in the soil-recycling machine with dual shafts in order to assist the economical and effective design of the optimum soil-recycling machine. By using the simulator, several simulations were carried out, and the effects of some mechanical parameters such as the paddle inclination angle and pitch of the paddle on the mixing performance were made clear.
An Experimental Investigation of a Plane Jet in a Wavy Crossflow
Authors: Abdel-Rahman A. A. , Eleshaky M. A.
Published: February 2009

An experimental investigation has been undertaken to study the effect of a wavy crossflow on a plane jet discharged vertically downward in a water channel. Two groups of experiments were performed; one group for a jet discharged into a uniform crossflow, the second group for a jet discharged into a wavy crossflow. Experiments were conducted for four jet-to-crossflow velocity ratios (R = 1, 3, 5, and 7). For each experiment, measurements using LDA system were made at six stations downstream of the exit of the jet nozzle (x = 0.0, 6, 12, 18, 27, and 36 mm). During the course of the experiments, the channel flow velocity was maintained fairly constant at 15 cm/s, and the wave generated in the channel was not very steep. The results revealed that the oscillatory motion associated with the waves has a significant effect on both the mean and turbulent velocity fields. The mean velocity profiles were found to have no maximum values, compared with those of a uniform crossflow. The effect was most pronounced in the zone of flow establishment, where a region of intense fluid mixing arises, resulting in a significant shortening of the zone and a rapid development of the jet flow.
A Numerical Simulation of Heat Pipe Application to the Cooling of Pulse Detonation Engines
Authors: Murty V. Dakshina
Published: February 2009

A numerical method based on the finite elements is applied to the cooling of pulse detonation tube using heat pipe technology. Towards this end, the fluid flow and heat transfer in the wick are modeled as flow in a porous medium. The flow is described using the so called Darcy Brinkman model which has close resemblance to the Navier-Stokes equations. It is found that for Darcy numbers less than 0.0001 the results are indistinguishable from regular Darcy flows. The shape of the heat pipe is that of a fin with the proportion of the length of the evaporator section being varied. In this study two values of this ratio have been used, namely 1 and 0.5.
Numerical Investigation on Small-Scale Cyclone for SPM Removal
Authors: Suguri Akihiko , Toda Kazuyuki , Yamamoto Makoto
Published: February 2009

Recently, the fine particles have been of major interest, since they suspend in the ambient air for a long time and cause to a respiratory disease. This kind of fine particles is referred to Suspended Particulate Matter (SPM). The diameter is less than 10.0 μm, and the typical generation source is the exhausted gas from diesel engines. On the other hand, a cyclone separator is expected to be the promising equipment to remove the fine particles. It is one of the most widely used devices to remove the dust from gas. However, an existing cyclone is generally large in scale, and thus its scale-down is needed to mount on a diesel vehicle. Thus, the performance of such a small-scale cyclone has to be clarified. The purpose of this study is to numerically evaluate the collection efficiency of a small-scale cyclone for particles less than 5.0 μm, and provide the suggestions for the preferable design. Performing the computations under three different conditions of a diesel engine operation, with using the Eulerian-Lagrangian method, the particle trajectories and the collection efficiency are investigated.
Effects of Turbulence on the Coagulational Growth of Cloud Droplets: An Overview and Recent Results (Keynote)
Authors: Wang Lian-Ping , Ayala Orlando , Xue Yan , Grabowski Wojciech W.
Published: February 2009

Although the importance of turbulence on rain formation was noted at least 60 years ago, progress has been very slow in quantifying the turbulence effects [1]. Adequate treatment of the turbulence effects on droplet growth represents a major gap in our understanding of cloud microphysical processes [2–7]. In this talk, we will discuss open issues in this subject, and report on an on-going, systematic effort to address various effects of turbulence on the growth of small cloud droplets to sizes for which the gravitational coagulation can operate effectively. We focus on the evolution in the size range from 10 μm to 100 μm for which the condensational growth is no longer an effective growth mechanism and gravitational coagulation alone is not sufficient to grow droplets at a rate typically observed. This size range involves a change of droplet inertial response time by roughly two orders of magnitude.
Real-Time On-Line Monitoring of Pulverized Coal at Power Stations
Authors: Cai Xiaoshu , Li Junfeng , Zhao Zhijun , Ouyang Xin , Huang Chunyang
Published: February 2009

The principle of light fluctuation is presented. Based on this method, a novel system for on-line real time measuring pulverized coal was developed by authors. This system may be used in both the direct firing pulverizing system and the indirect firing pulverizing system. The results of over-one-year monitoring in a 300 MW utility boiler and many measurements in utility boilers with the capacities from 300MW to 600 MW show that the system can reliably measure particle size, concentration and velocity of pulverized coal.
Fully Resolved Simulations of Stationary Particles in Turbulent Flow
Authors: Burton Tristan M. , Eaton John K.
Published: February 2009

Gas flows containing a dilute loading of solid particle constitute an important class of multiphase flows. In most cases the gas flow is turbulent, and the interactions between the particles and the turbulence offer major modeling challenges. Many numerical models implicitly assume that the particles are significantly smaller than all turbulence length scales. Simple particle drag laws derived for uniform steady flow around a sphere are used to compute the motion of point-particles, and to determine the magnitude of the point-forces that are applied to the gas phase in order to produce turbulence modification. This technique may be appropriate if the particle is small relative to any turbulent eddies, but in many practical problems the particle diameter, d, is of the same order as the flow Kolmogorov scale, η. Here we perform fully-resolved simulations of a fixed particle in decaying homogeneous isotropic turbulence using an overset grid method. All flow scales are accurately resolved with this technique including the effect of the no-slip boundary condition at the particle surface. A set of 29 simulations with an initial Taylor microscale Reynolds number, Reλ = 32.2, and Kolmogorov length scale, η = 0.45d are computed to obtain a useful statistical sample. The turbulent kinetic energy and viscous dissipation near the particle surface in laden and unladen simulations are compared to provide understanding of the turbulence modification process. We anticipate that these results will provide direction for the development of turbulence modification models suitable for larger scale simulations where the flow cannot be resolved to the particle surface.
Effect of Particle Size on Velocity Correlations in Turbulent Channel Flow
Authors: Khalitov Daniel A. , Longmire Ellen K.
Published: February 2009

The response of glass beads was examined in a fully developed turbulent channel flow of air with Reynolds number Reh = 4500 where h is the channel half width. Five sets of monodisperse particles were tested with integral Stokes numbers in the range 0.2–10 at the channel centerplane. Particle-to-air mass loadings were of order 10%. Laser sheets were aligned in streamwise-spanwise flow planes, and seeded, particle-laden flow was imaged with a dual-frame camera. A separation algorithm was used to obtain simultaneous gas and particle velocity measurements of homogeneous flow planes over a range of wall-normal distances. Profiles of single-point velocity statistics including mean and rms slip velocity, particle drift velocity, and gas-particle correlation were computed. In addition, two-point gas-particle and particle-particle velocity correlations were obtained. Near the wall, the gas-gas correlations yielded long, narrow patterns related to near-wall low-speed streaks. At the centerplane, the correlations were broader in the spanwise direction. Gas-particle and particle-particle correlations resembled the gas correlations in shape and size, but the values were smaller. The gas-particle covariance tended toward zero for St = 10. Particle-particle correlations were still significant for St = 4.
An Experimental Study With Minimum Transport Velocity of Dilute Gas-Solid Two-Phase Flow in a Vertical Pipe
Authors: Ochi Mitsuaki , Nishimura Hiroshi , Takei Masahiro
Published: February 2009

A simple empirical equation of the minimum transport velocity of a dilute two-phase flow for granular solids in a vertical pipe has been derived on the basis of both a dynamic model equation and the transport experiment. The minimum transport velocity means here the limiting air velocity at which conveying is possible in a state in which particles are not stagnant or recircular in the pipe. As a result, it is found that the empirical equation of the minimum transport velocity, simply called the minimum velocity, can arrange the data of this study with a pretty good accuracy.
Modeling of Kinetic Energy Transfer by Collision in a Non-Settling Binary Mixture of Particles Suspended in a Turbulent Homogeneous Isotropic Flow
Authors: Fede Pascal , Simonin Olivier
Published: February 2009

The general purpose of this paper is the modelling of particle-particle interactions in binary mixture of particles suspended in turbulent flows. The model predictions are compared with statistics issued from Large Eddy Simulation of an homogeneous isotropic gas coupled with Discrete Particle Simulation of a non-settling mixture.
Monte Carlo Simulation of Colliding Particles Suspended in Gas-Solid Homogeneous Turbulent Shear Flows
Authors: Moreau Mathieu , Fede Pascal , Simonin Olivier , Villedieu Philippe
Published: February 2009

The purpose of this paper is the modelling of particle-particle collisions by Stochastic Lagrangian approach in gas-solid turbulent shear flows. A generalized Monte Carlo algorithm is introduced which takes into account the correlation between the colliding particles. Particle-particle and fluid-particle velocity correlations from Stochastic Lagrangian simulations are compared with results from Deterministic Particles Simulation coupled with Large Eddy Simulation of a gas turbulent shear flow (DPS/LES), and with predictions computed in the frame of the moment method using separate transport equation for the fluid and particle velocity correlations.
Transfer, Segregation and Deposition of Heavy Particles in Horizontal and Vertical Turbulent Channel Flows
Authors: Marchioli Cristian , Sbrizzai Fabio , Soldati Alfredo
Published: February 2009

Particle transfer in the wall region of turbulent boundary layers is dominated by the coherent structures which control the turbulence regeneration cycle. Coherent structures bring particles toward the wall and away from the wall and favour particle segregation in the viscous region giving rise to nonuniform particle distribution profiles which peak close to the wall. In this work, we focus on the transfer mechanism of different size particles and on the influence of gravity on particles deposition. By tracking O(105) particles in Direct Numerical Simulation (DNS) of a turbulent channel flow at Reτ = 150, we find that particles may reach the wall directly or may accumulate in the wall region, under the low-speed streaks. Even though low-speed streaks are ejection-like environments, particles are not re-entrained into the outer region. Particles segregated very near the wall by the trapping mechanisms we investigated in a previous work [1] are slowly driven to the wall. We find that gravity plays a role on particle distribution but, for small particles (τp+ < 3), the controlling transfer mechanism is related to near-wall turbulence structure.
Lattice Boltzmann Simulation to Determine Forces Acting on Non-Spherical Particles
Authors: Ho¨lzer A. , Sommerfeld M.
Published: February 2009

The paper is divided into two parts. In the first part the forces acting in the steady state on a cuboid in an incompressible plug flow with respect to the angle of incidence and to the particle Reynolds number are calculated. These forces are the drag force acting in flow direction and the lift force acting perpendicular to the flow direction for fixed particles and additionally the Magnus force for rotating particles. A non-uniform distribution of the force along the particle surface causes a torque and thereby a rotation of a moving particle. In the second part the resulting orientation of a long cylinder in laminar channel flow and in turbulent flows is analysed. All simulations are performed by the three-dimensional lattice Boltzmann method (LBM).
Numerical Simulation of Sand Erosion in Steam/Water Separator
Authors: Kato Susumu , Toda Kazuyuki , Yamamoto Makoto , Shito Motoaki , Kawai Masafumi
Published: February 2009

This paper presents an investigation into a phenomenon that happened on the wall surface of a Steam / Water Separator (SWS). It was reported that erosion caused from unknown solid particle took place on the SWS wall. In order to capture this sand erosion phenomenon numerically, the SWS flow field was solved, and then particle trajectory and wear quantity were calculated, based on the CFD results. Several wall and particle materials and also the combinations of them are assumed. Furthermore, the particle diameter was varied from 10−6 to 10−2 m. The numerical results insist that the particle, which could be the factor of the phenomenon, is limited in its diameter range and its material. The present study will be an aid to clarify the cause of sand erosion in a SWS.
Effects of Long and Short Relaxation Times of Particle Interactions in Dense and Slow Granular Flows
Authors: Zhang Duan Z. , Rauenzahn Rick M.
Published: February 2009

The rheological properties and the duration of particle interactions in a dense granular media are closely related to the formation of particle interaction networks. The behavior of particle interaction networks depends not only on the particle volume fractions but also on friction between particles. For examples, for frictionless particles, a particle interaction network may not form at particle volume fraction greater than 0.62, the random dense packing volume fraction for monodisperse spheres. Without network formation, particle interactions are short in time and mostly binary. Under this condition, the granular medium can be modeled as a viscous fluid with variable viscosity as in kinetic theory. Formation of particle interaction networks dramatically increases particle interaction time and results in a phase transition in the constitutive relations of the granular medium. Then, the stress relaxation time is inversely proportional to the macroscopic shear rate in simple shear flows, and the granular medium can be modeled as a viscoelastic material with a stress relaxation time depending on the macroscopic shear rate. For small shear rates, the stresses in the granular medium are independent of macroscopic shear rates in simple shear flows. Thus, as the shear rate approaches zero, the relaxation time approaches infinity, and the shear stress approaches a finite value, the yield stress, instead of zero. We also studied the relaxation behavior of the stress tensor under time-dependent shear rates. The dynamics of the particle interaction network leads to a nonlinear behavior of stress relaxation not exhibited by ordinary viscoelastic materials, such as polymeric fluids.
Simulation of Gas-Particle Channel Flows Using a Two-Fluid Particle-Wall Collision Model Accounting for Wall Roughness
Authors: Zhang X. , Zhou L. X.
Published: February 2009

A two-fluid particle-wall collision model accounting for wall roughness is proposed. It accounts for the effects of wall friction, restitution, in particular the wall roughness, and hence the redistribution of particle Reynolds stresses in different directions at the wall, the absorption of turbulent kinetic energy from the kinetic energy of mean motion at the wall and the attenuation of particle motion by the wall. It gives the effect of wall roughness on the particle turbulence. The proposed model is applied to simulate gas-particle horizontal channel flows and is validated using PDPA measurement results. It is shown that presently used zero-gradient boundary conditions and other collision models of particle phase might give false results.
Optimization of Micro Compressor Blades Using CFD Analysis and Artificial Intelligence
Authors: Islek Akay A.
Published: February 2009

This paper describes a robust design method for turbo machinery components. The method which uses a Navier Stokes (NS) solver, an Artificial Neural Network (ANN) and a Genetic Algorithm (GA) is applied to optimize radial micro compressor blades. Higher efficiency, less divergence from the design mass flow and smoother Mach number distributions are considered as objectives of the optimization.
Computational Fluid Dynamics Simulations of the Container Express as a Helicopter Slung Load
Authors: Berry Misty G.
Published: February 2009

Flow over rectangular boxes and cylinders has not been well studied, and yet has numerous practical applications. This bluff-body geometry causes immediate flow separation and periodic vortex shedding in the wake of the object, regardless of Reynolds number. This paper presents the use and verification of a CFD methodology for predicting the forces on a particular rectangular cylinder—a slung load cargo container known as a Container Express (CONEX). It presents a comparison of the numerically obtained forces to wind tunnel data for the CONEX that demonstrates ranges of validity for the simulations. These comparisons give confidence for force and moment results for CONEX and vertical stabilizer simulations. The forces and moments will be used to design a mounting system for the vertical stabilizer.
Numerical Analysis of Sound Generation by a Two-Dimensional Cylinder in a Uniform Flow
Authors: Imamura Ayaka , Hatakeyama Nozomu , Inoue Osamu
Published: February 2009

The sound generated by a squarer cylinder in a uniform flow is investigated by direct numerical simulation of the two-dimensional compressible Navier–Stokes equations. The characteristic features of the generated sound are investigated and compared for different configurations and angles of attack. Results show that sound pressure waves are generated by vortex shedding from the cylinder into its wake. The sound field is dominated by lift dipole. The effect of the angle of attack on the sound generation and propagation is also analyzed.
CFD Visualization of Drop Generation From a Nozzle
Authors: Honda Haruhisa
Published: February 2009

Drop generation from a single nozzle is visualized by direct numerical simulations. Navier-Stokes equations are solved on cylindrical axisymmetric coordinates, and interfacial motion is traced by a Front-Tracking method. To validate the numerical code, the numerical results for two modes, dripping and jetting, are compared with experimental results, and they show good agreement. The experimental result that shows a formation of a small satellite, in particular, is successfully visualized. It is shown that the formation of the satellite is due to the strong back flow arising from the large interfacial tension at the cusp behind the primary drop.
Micro Chemical Reaction Flow Measurement Using PIV and LIF Technique
Authors: Shinohara Kyosuke , Sugii Yasuhiko
Published: February 2009

Using micro PIV technique and micro LIF technique, velocity distributions and pH distributions of chemical reacting flow in micro fluidic device were measured. The micro fluidic device was Y-junction channel. In order to generate a neutralization reaction, acetic acid and ammonia hydroxide were introduced into each channel respectively. The results of velocity profiles of the chemical reacting flow corresponded closely to the theoretical profile of Poiseuille’s flow. This was characteristic of laminar flow. The results of pH distribution of the chemical reacting flow showed two kinds of distribution. In one case interface was straight and mixing was not noticeable at higher flow speed. In the other hand mixing or molecular diffusion due to chemical reaction definitely caused at lower flow rate. Applying both results we compared the experimental diffusion with theoretical value. In one case the experimental result corresponded close to theoretical value. However, it did not agree with theory in the other case. The results indicate that acetic acid and ammonia hydroxide mixed faster than theory in micro scale.
Modeling and Computational Study on Microbubble Two-Phase Turbulent Flow
Authors: Arakawa Toru , Toda Kazuyuki , Yamamoto Makoto
Published: February 2009

The drag reduction is needed for the economical ship operations and the suppression of CO2 emission. Microbubble injection is one of the promising techniques for the purpose. It was experimentally confirmed that the skin friction could be reduced remarkably, by injecting the microbubbles with the diameter of 0.5 to 1.0mm from the bottom of a ship hull. Although a great number of papers can be seen in the literatures, unfortunately, the efficient and accurate computer code, which can calculate the global flow phenomenon around a ship hull and can be used in the ship design, has never been developed. In the present study, the correlations between liquid and microbubbles are modeled and computed, by using the two-fluid model. The Reynolds stress transport model is employed for the accurate prediction of the bubble behavior around a ship. The present model is tuned and verified, based on the fundamental experiment conducted by Kodama et al. in 2000. Furthermore, using the present model, the drag reduction mechanism by microbubbles is numerically investigated for a wide variety of void fraction and flow conditions. It is confirmed that the present Reynolds stress model can capture the characteristic of drag reduction by the microbubbles.
A Level Set Approach to 3D Mold Filling of Newtonian Fluids
Authors: Baer Thomas A. , Noble David R. , Rao Rekha R. , Grillet Anne M.
Published: February 2009

Filling operations, in which a viscous fluid displaces a gas in a complex geometry, occur with surprising frequency in many manufacturing processes. Difficulties in generating accurate models of these processes involve accurately capturing the interfacial boundary as it undergoes large motions and deformations, preventing dispersion and mass-loss during the computation, and robustly accounting for the effects of surface tension and wetting phenomena. This paper presents a numerical capturing algorithm using level set theory and finite element approximation. Important aspects of this work are addressing issues of mass-conservation and the presence of wetting effects. We have applied our methodology to a three-dimension model of a complicated filling problem. The simulated results are compared to experimental flow visualization data taken for filling of UCON oil in the identical geometry. Comparison of simulation and experiment indicates that the simulation conserved mass adequately and the simulated interface shape was in approximate agreement with experiment. Differences seen were largely attributed to inaccuracies in the wetting line model.
Drag of a Circular Cylinder in Surfactant Solutions at Intermediate Reynolds Number Range
Authors: Ogata Satoshi , Watanabe Keizo , Osano Yoshihisa
Published: February 2009

To clarify the behavior of the drag coefficient of a circular cylinder in the intermediate Reynolds number range, the flow around a circular cylinder in surfactant solutions was investigated experimentally by measurement of the drag in the Reynolds number range of 3 × 102 to 7 × 103. The experiments were performed in a vertical re-circulating water tunnel. The drag coefficient was measured using an apparatus which could measure the drag acting on the circular cylinder directly. Five cylinders of diameter d = 5, 7, 10, 13 and 20 mm were tested, the ratios of length to diameter (l/d) were 12, 24 and 48. The test surfactant solutions were aqueous solutions of Ethoquad O/12 at concentrations of 50, 100 and 200 ppm, and sodium salicylate was added as a counterion. It was clarified that the drag coefficient of the cylinder in surfactant solutions increased comparing that in tap water in the Reynolds number lower approximately 103 < Re < 3 × 103. According to the increase of the Reynolds number, the drag coefficient decreased. When Reynolds number exceeded approximately 103 < Re < 3 × 103, the drag coefficient in surfactant decreased in comparison with that in tap water finally. In other ward, the drag reduction occurred in this Reynolds number range. The maximum drag reduction was about 55% for 200 ppm solution and 20mm diameter at Re ≅ 7 × 103. The value of the drag coefficient in surfactant solutions was dependent on not only (l/d) but also cylinder diameter. The drag coefficient increased with increasing cylinder diameter. The increase in the concentration of surfactant solution emphasized the characteristics of drag reduction and drag increase.
Fiber Orientation and Concentration Distribution in a Concentrated Suspension Flow Through a Complex Geometry
Authors: Yasuda Kazunori , Mori Noriyasu
Published: February 2009

Distributions of fiber orientation and fiber concentration in slit flows of concentrated suspensions were measured. Slit channels were used in the experiments: a channel with an abrupt expansion and a crank geometry with six L-shaped corners. Such channels are usually used in a polymer processing. For visualization of fibers, an index-of-refraction matching method was employed, and tracer fibers having birefringence were suspended to observe between crossed polarizers. When fibers flow through an abrupt expansion, they rapidly orient in the direction perpendicular to the flow direction near the centerline. The fiber orientation, however, returns to the flow direction in the downstream region. In the L-shaped corner, fibers randomly orient because of the decelerating flow. In the downstream region of the L-shaped corner, fiber orientation is not symmetric with respect to the centerline. This seems to result from fiber-fiber interactions in the concentrated suspension. The fiber concentration is uniform over a width of a channel except adjacent to the side wall in the concentrated suspension, while it has a maximum apart from the side wall in the dilute suspension.
Numerical Simulation and Experimental Study of Gas Flow Dynamics in Porous Media: Application in Cold Box Foundry Process
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A.
Published: February 2009

The results of an experimental study and 3D numerical simulations of resin bonded sand/air flow in a square corebox with an H-shape insertion and passage between upper and lower pockets of the pattern are presented. A computer controlled electronic system was designed and built to measure pressures and flow rates inside the corebox during mold filling, gassing and purging cycles of Phenolic Urethane Amine (PUA) process. Contour maps of the pressure distributions inside the corebox were created based on barometric measurements. A good agreement between experimental results and numerical simulations was found.
Turbulent Mixing of Two Immiscible Fluids
Authors: Lemenand Thierry , Dupont Pascal , Della Valle Dominique , Peerhossaini Hassan
Published: February 2009

The global trend in chemical and manufacturing industries is towards improved energy efficiency, cleaner synthesis, reduced environmental impact and smaller, safer, multifunctional process plants. Such concerns are the driving force for the intensification of batch processes, which are being replaced with continuous high-intensity in-line mass- and heat-transfer equipment. In this context the process intensification (PI) approach, in which the fluid dynamics of the process is matched to the reaction in order to improve selectivity and minimize the byproducts, takes on particular importance.
Experimental and Numerical Study of Supersonic Radial Jet
Authors: Sakakibara Yoko , Endo Masaki , Iwamoto Junjiro
Published: February 2009

When an axisymmetric underexpanded jet impinges on a flat plate perpendicularly, the feedback loop of the sound waves in and around the jet is known to cause the oscillation of the whole flow field. In this paper, the radial underexpanded jet issuing from a slit nozzle which consists of two tubes, face to face each other, is studied experimentally and numerically. Such flow field can be considered as a simple model of the wall jet of the impinging jet on the plate. In the experimental photograph, it is found that some shock rings appear around the nozzle and that the distortion and the deformation of the rings occur. They are considered to be caused by the sinusoidal oscillation of the jet and the motion of the vortices around the jet. Such oscillatory phenomena are shown by the computational results. Furthermore, the feedback mechanism of the readial jet is also discussed under the assumption of the axisymmetric flow field.
Motion of a Highly Water-Repellent Sphere in Newtonian Fluids
Authors: Watanabe Keizo , Fujita Takao
Published: February 2009

It has, recently noticed the flow characteristics on a highly water-repellent wall on which a gas-liquid interface occurs near the solid surface. We have reported the drag reduction of flow around a circular cylinder with a highly water-repellent wall where fluid slip occurred at the wall and the separation point moved downstream compared with the case of a circular cylinder with a smooth solid surface. On the other hand, we have discovered that a gas-phase film of about 60–90 μm covered the sphere with a highly water-repellent surface, when the sphere was soaked in water. A new practical use of this phenomenon is to give buoyancy to the sphere while the sphere retains the gas-phase film in the flow field, for surfaces with the hydrophobic property. We clarified the effect of the gas-phase film on the fall velocity of a highly water-repellent sphere in Newtonian fluids. Experiments were carried out to measure the thickness of the film by the contact needle method and the fall velocity by the falling sphere method in the Reynolds number range of 171 < Re < 10032. Consequently, it was clarified that the thicknesses of gas-phase films are almost constant. Films can be made to form at the thicknesses of Duracon and Nylon, 91μm and 61μm, on the highly water-repellent surface. The terminal velocity of the highly water-repellent sphere decreases more than that of the normal smooth sphere. The maximum velocity deceleration ratios were 61% for Nylon and 42% for Duracon spheres. It was clarified that a sphere with density greater than that of water floats on the water surface when it is covered with the gas-phase film. The results have obtained that the phenomenon can be applied to the prevention of the precipitation of solid spheres and particles.
Flow of Newtonian and Non-Newtonian Fluids in a Concentric Annulus With Rotation of the Inner Cylinder
Authors: Kim Young-Ju , Woo Nam-Sub , Hwang Young-Kyu
Published: February 2009

This experimental study concerns the characteristics of vortex flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one is rotating. Pressure losses and skin friction coefficients have been measured for fully developed flows of water and of 0.4% aqueous solution of sodium carboxymethyl cellulose (CMC), respectively, when the inner cylinder rotates at the speed of 0∼600 rpm. The results of present study reveal the relation of the bulk flow Reynolds number Re and Rossby number Ro with respect to the skin friction coefficients. In somehow, they show the existence of flow instability mechanism. The effect of rotation on the skin friction coefficient is significantly dependent on the flow regime. In all flow regime, the skin friction coefficient is increased by the inner cylinder rotation. The change of skin friction coefficient corresponding to the variation of rotating speed is large for the laminar flow regime, whereas it becomes smaller as Re increases for the transitional flow regime and, then, it gradually approach to zero for the turbulent flow regime. Consequently, the critical (bulk flow) Reynolds number Rec decreases as the rotational speed increases. Thus, the rotation of the inner cylinder promotes the onset of transition due to the excitation of Taylor vortices.
Experiments and Modeling in Bubbly Flows at Elevated Pressures
Authors: Kumar R. , Trabold T. A. , Maneri C. C.
Published: February 2009

Measurements of local void fraction, rise velocity and bubble diameter have been obtained for cocurrent, wall-heated, upward bubbly flows in a pressurized refrigerant. The instrumentation used was the gamma densitometer and the hot-film anemometer. Departure bubble size and bulk size measurements were also made and correlated with appropriate parameters. Flow visualization techniques have also been used to understand the two-phase flow structure and the behavior of the bubbly flow for different bubble shapes and sizes, and to obtain the rise velocity. Such insight, coupled with quantitative local and averaged data on void fraction and bubble size at different pressures, has aided in developing bubbly flow models applicable to heated two-phase flows at high pressure.
Why the Multiphase Flow Community Should Be Interested in the Office of Science at the U.S. Department of Energy
Authors: Fitzsimmons Timothy
Published: February 2009

This presentation is to introduce the Engineering Physics Program within the Office of Basic Energy Sciences in the Office of Science (SC) at the U.S. Department of Energy (DOE). The program portfolio covers fundamental scientific investigations in theory, simulation and experiment on multiphase fluid dynamics, granular materials, heat transfer and other areas. The unique characteristics of current and planned SC/DOE experimental and computational user facilities are described as well as opportunities within DOE experimental facilities for the development of capabilities to characterize multiphase flow. Opportunities and the process for obtaining future research support are discussed.
The Role of CFD in Preliminary Aerospace Design (Keynote)
Authors: Jameson Antony
Published: February 2009

This paper discusses the role that computational fluid dynamics plays in the design of aircraft. An overview of the design process is provided, covering some of the typical decisions that a design team addresses within a multi-disciplinary environment. On a very regular basis trade-offs between disciplines have to be made where a set of conflicting requirements exists. Within an aircraft development project, we focus on the aerodynamic design problem and review how this process has been advanced, first with the improving capabilities of traditional computational fluid dynamics analyses, and then with aerodynamic optimizations based on these increasingly accurate methods.