bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating Using Oscillating Jets for Fluid Mixing
Authors: Bamberger Judith Ann , Meyer Perry A.
Published: August 2009

Scaled mixing experiments were conducted to evaluate maintaining mobilized particles in a uniform suspension (the condition of concentration uniformity) using jet pumps to mix the suspension. The study experimentally evaluated uniformity in a 1/12-scale experiment varying the Reynolds number, Froude number, and gravitational settling parameter space. The product of the jet exit velocity and nozzle diameter (U0D0) was used to scale the experimental conditions. The test matrix included a full factorial test between 100% and 50% U0D0 and two half-factorial tests at 75% and 25% U0D0. Evaluating points at 75% U0D0 and 50% U0D0 allowed evaluation of curvature. Eliminating points at 25% U0D0 decreased the testing time by several weeks. Test conditions were achieved by varying the simulant viscosity (μ), the mean particle size (dp), and the jet nozzle exit velocity (U0). Concentration measurements at sampling locations throughout the tank were used to assess the degree of uniformity achieved during each test. Concentration data was obtained using a real time ultrasonic attenuation probe and discrete batch samples. The undissolved solids concentration at these locations was analyzed to determine whether the tank contents were uniform (< ±10% variation about mean) or nonuniform (> ±10% variation about mean) in concentration. Concentration inhomogeneity was modeled as a function of dimensionless groups. The two parameters that best describe the maximum solids volume fraction that can be suspended in a double-shell tank were found to be 1) the Froude number (Fr) based on nozzle velocity (U0) and tank contents level (H) and 2) the dimensionless particle size (dp/D0). The dependence on the Reynolds number (Re) does not appear to be statistically significant.
Dynamic Modeling of Refrigeration Cycle for Electronics Cooling
Authors: Zhang Tiejun , Catano Juan , Zhou Rongliang , Wen John T.
Published: August 2009

In this paper a refrigeration cycle consisting of multiple evaporators, liquid accumulator, compressor, condenser and expansion valves is analyzed. In the cycle the evaporators and condenser are treated as dynamic components while the liquid accumulator, compressor and the expansion valve are consider static components. For the dynamic components, equations for conservation of mass, energy and momentum are used to characterize the comprehensive transient behaviors. One of the differences with previous models is the use of the momentum equation which is typically neglected in traditional vapor compression refrigeration systems, but it is important in electronics cooling where microchannels are commonly used and a significant pressure drop is observed in the evaporator. This model is expected to have higher accuracy than previously used lumped parameter approximation while maintaining its simplicity to be useful for control purposes. The compressor and expansion valves are modeled using empirical relations, the accumulator is used to guarantee proper operation of the compressor. Local system stability is analyzed using a linearized model at some operating condition and an experimental testbed is developed to validate the model. The test bed consists of three electrically controlled heaters immersed in the refrigeration loop which act as the evaporators. A heated tank as an accumulator for operation at wide range of operating conditions, including low quality at the evaporator outlets. A reciprocating compressor with variable frequency drive to operate at various mass flow rates. The condenser is a flat plate heat exchanger and finally three electronically controlled expansion valves for evaporators.
Numerical Analysis of Sub-Millimeter-Scale Microturbomachinery Aerothermodynamics
Authors: Martel Philippe B. , Fre´chette Luc G.
Published: August 2009

This paper presents a complete numerical study of the aerothermodynamics of subsonic moderate Reynolds number microturbomachinery using 2D computational fluid dynamics (CFD) on 24 cascade geometries and covering over 2000 conditions. Profile and mixing losses, as well as deviation and heat transfer correlations are developed for use in mean-line analysis and design. Both losses and thermal transfer tend to increase with decreasing Reynolds number, Mach number, and throat width. Deviation follows large scale turbomachinery behavior but tends to increase with viscous effects. A slender cascade geometry using a modified profile is suggested, potentially increasing isentropic efficiency by as much as 15%. This work defines a solid foundation for the design of microturbines used in power microelectromechanical systems (MEMS), such as gas and steam microturbines with sub-millimeter-scale blade chords operating at moderate Reynolds numbers (100 < Rec < 2000).
Experimental Study of Adiabatic Water Liquid-Vapor Two-Phase Pressure Drop Across an Array of Staggered Micro-Pin-Fins
Authors: Konishi Christopher A. , Qu Weilin , Jasperson Ben , Pfefferkorn Frank E. , Turner Kevin T.
Published: August 2009

This study concerns pressure drop of adiabatic water liquid-vapor two-phase flow across an array of 1950 staggered square micro-pin-fins having a 200×200 micron cross-section by a 670 micron height. The ratios of longitudinal pitch and transverse pitch to pin-fin equivalent diameter are equal to 2. An inline immersion heater upstream of the micro-pin-fin test module was employed to produce liquid-vapor two-phase mixture, which flowed across the micro-pin-fin array. The test module was well insulated to maintain an adiabatic condition. Four maximum mass velocities of 184, 235, 337, and 391 kg/m2s, and a range of vapor qualities for each maximum mass velocity were tested. Measured pressure drop increases drastically with increasing vapor quality. Nine existing two-phase pressure drop models and correlations were assessed. The Lockhart-Martinelli correlation for laminar liquid-laminar vapor combination in conjunction with a single-phase friction factor correlation proposed for the present micro-pin-fin array provided the best agreement with the data.
Heat Flux Determination From Ultrasonic Pulse Measurements
Authors: Myers M. R. , Walker D. G. , Yuhas D. E. , Mutton M. J.
Published: August 2009

Ultrasonic time of flight measurements have been used to estimate the interior temperature of propulsion systems remotely. All that is needed is acoustic access to the boundary in question and a suitable model for the heat transfer along the path of the pulse train. The interior temperature is then deduced from a change in the time of flight and the temperature dependent velocity factor, which is obtained for various materials as a calibration step. Because the acoustic pulse samples the entire temperature distribution, inverse data reduction routines have been shown to provide stable and accurate estimates of the unknown temperature boundary. However, this technique is even more interesting when applied to unknown heat flux boundaries. Normally, the estimation of heat fluxes is even more susceptible to uncertainty in the measurement compared to temperature estimates. However, ultrasonic sensors can be treated as extremely high-speed calorimeters where the heat flux is directly proportional to the measured signal. Through some simple one-dimensional analyses, this work will show that heat flux is a more natural and stable quantity to estimate from ultrasonic time of flight. We have also introduced an approach for data reduction that makes use of a composite velocity factor, which is easier to measure.
Flow in a Curved Rectangular Channel With Variable Cross-Section Area
Authors: Bhunia Avijit , Chen C. L.
Published: August 2009

Laminar air flow through a curved rectangular channel with a variable cross-section (c/s) area (diverging-converging) is numerically investigated. Such a flow passage is formed between the two fin walls of a 90° bend curved fin heat sink, used in avionics cooling. Simulations are carried out for two different configurations — (a) a curved channel with long, straight, constant c/s area inlet and outlet sections (entry and exit lengths), and (b) a short, curved channel with no entry and exit lengths. Formation of a complex, 3-D flow pattern and its evolution in space is studied through numerical flow visualization. Results show that a secondary motion sets in the radial direction in the curved section, which in combination with the axial (bulk) flow leads to the formation of a base vortex. In addition, under certain circumstances the axial and secondary flow separate from multiple locations on the channel walls, and create Dean vortices and separation bubbles. The role of variable c/s geometry is elucidated by comparing the results with those of a constant c/s area, curved channel. Investigation of the dimensionless friction factor reveals that the overall channel pressure drop is governed by both the curvature effect as well as the area expansion effect. Due to the combined effect pressure drop for developing flow in a short, curved channel can be even less than that of a straight channel.
Damping in Lap Joints Due to Partial and Full Micro-Slip Using a Three Dimensional Elastic Contact of Rough Surfaces
Authors: Farhang K. , Sepehri A. , Segalman D. , Starr M.
Published: August 2009

Energy dissipation in mechanical joints occurs as a result of micro-slip motion between contacting rough surfaces. An account of this phenomenon is especially challenging due to the vast differences in the length and time scale differences between the macro-mechanical structure and the micron-scale events at the joint interface. This paper considers the contact between two nominally flat surfaces containing micron-scale roughness. The rough surface interaction is viewed as a multi-sphere elastic interaction subject to a periodic tangential force. It combines the Mindlin’s formulation [1, 2] for the elastic interaction of two spheres with the Greenwood and Williamson’s [3] statistical approach for the contact of two nominally flat rough surfaces so as to develop a model for multi-sphere problem in which sphere radii, contact load and the number of spheres in contact can only be known in a statistical sense and not deterministically.
Bachelor of Science: Engineering Technology Hydrogen and Fuel Cell Education Program Concentration — I
Authors: Sleiti A. K.
Published: August 2009

This paper reports proposed efforts to develop a program focused on Hydrogen and Fuel Cell Technology (HFCT) in Engineering Technology Department (ENT) jointly with the Florida Solar Energy Center (FSEC) at University of Central Florida (UCF). The HFCT Program intends to support the need for educated graduates that comprise the next generation workforce needed for research, development, and demonstration activities in government, industry, and academia. The proposed project will include the development and delivery of undergraduate courses at Engineering Technology Department and FSEC within the ABET accredited Bachelor of Science in Engineering Technology (BSET) program. The mode of course offering will be both in class and on line, which will increase the number of students. The proposed project facilitates are located at College of Engineering and Computer Science (CECS) and at FSEC of UCF. The Florida Solar Energy Center is a unique component of the proposed effort. FSEC has been conducting hydrogen and fuel cell research for 25 years and FSEC has dedicated facilities and a selection of unique laboratory equipment that will be made available to the students for this project. These attributes will allow the students to be trained on the state-of-the-art equipment and facilities. Both ENT and FSEC faculties will participate in the teaching and training of the prospective students.
Dielectrophoretic Force-Induced Assembly Technique for the Fabrication of 2D Colloidal Photonic Crystals
Authors: Asmatulu R. , Kim S. , Papadimitrakopoulos F. , Marcus H.
Published: August 2009

Dielectrophoretic force-induced assembly technique was used to achieve close-packed 2D colloidal photonic crystals on parallel plate gold electrodes. These gold electrodes were patterned using conventional UV photolithography technique. The width and length of the parallel plates were 280 μm and 3 mm, respectively. The experimental tests conducted with 5.3 μm carboxyl functionalized polystyrene (PS) particles at various AC voltages, frequencies and particle concentrations showed that colloidal photonic crystals were fabricated on the ground electrode, instead of the working electrode, which may be attributed to the electro-osmotic flow and dipole-dipole attractions between the colloidal particles. It is concluded that this study provides promising results for the 2D colloidal photonic fabrication for the photonic industry.
Fabrication of Magnetic Nanocomposite Spheres for Targeted Drug Delivery
Authors: Asmatulu R. , Fakhari A. , Wamocha H. L. , Hamdeh H. H. , Ho J. C.
Published: August 2009

Biodegradable magnetic nanocomposite spheres were synthesized using magnetite nanoparticles and poly (D,L-lactide-co-glycolide) (PLGA) for the purpose of magnetic targeted drug delivery. Magnetic nanoparticles (∼10 nm) were prepared by a chemical co-precipitation of ferric and ferrous chloride salts in the presence of a strong basic solution (ammonium hydroxide). An oil-in-oil emulsion/solvent evaporation technique was conducted at 7000 rpm and 1.5–2 hrs agitation for the synthesis of nanocomposite spheres. Prior to the experiment, PLGA was dissolved in acetonitrile (phase I), and then added drop-wise into the viscous paraffin oil combined with Span 80 (phase II). The effect of magnetic particle concentrations (0%, 5%, 10%, 20% and 30%) on nanocomposite particles, the particle distribution and morphology were investigated using dynamic laser light scattering (DLLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The test results proved that the magnetic nanocomposite spheres were in the range of 200 nm to 1.03 μm.
Simulation of Direct Injection Gasoline Sprays Using Multi-Level Dynamic Mesh Refinement
Authors: Xue Qingluan , Kong Song-Charng
Published: August 2009

Accurate engine spray simulation often requires the use of a fine mesh which, in turn, will need extensive computer time. An adaptive mesh refinement scheme has been developed to improve the computational efficiency. This study further enhances the accuracy of spray modeling by implementing multi-level mesh refinement to simulate transient engine sprays. The solid-cone and hollow-cone sprays under direct-injection gasoline engine conditions were simulated. Predicted spray characteristics of using different mesh densities with various refinement levels were compared. Results show that the present mesh refinement scheme can accurately predict spray structures with reduced computer times. A significant computational speed-up was achieved by using a relatively coarse mesh with multi-level refinement while maintaining a good level of accuracy.
An Integrated Introduction to Engineering Mechanics: A Continuum Approach
Authors: Rossmann Jenn S. , Dym Clive L. , Bassman Lori C.
Published: August 2009

The essence of continuum mechanics, the internal response of materials to external loading, is often obscured by the complex mathematics of its formulation. Rather than introducing solid and fluid behavior as two distinct fields and waiting for an advanced course to demonstrate the mathematical connections between them, we have developed an integrated introduction to both fields. We will discuss the eight-year history of this course at Harvey Mudd and Lafayette Colleges, and the course materials we have developed. This one semester course covers material typically spread over several courses, including statics, strength of materials, and introductory fluid mechanics. We posit a spectrum of material behavior that has Hookean solids at one extreme, and Newtonian fluids at the other, with many interesting combinations (e.g. biomaterials, viscoelastic materials) in between. By building progressively from one-dimensional to higher dimension formulations, we are able to make continuum concepts such as the Cartesian stress tensor accessible to early undergraduate students. From this gradual development of ideas, with many illustrative case studies interspersed, students develop both physical intuition for how engineering materials behave, and the mathematical techniques needed to describe this behavior. We will discuss the rewards and challenges of introducing continuum mechanics early in the curriculum.
A Hardware-in-the-Loop Simulation Testbed for Emulating Hydraulic Loads Representing the Complete Dig Cycle of a Construction Machine
Authors: Enes Aaron R. , Book Wayne J.
Published: August 2009

A hardware-in-the-loop (HIL) simulation testbed is designed to be capable of emulating the entire domain of hydraulic workport loads incident on a test valve during normal work cycle operations of a certain hydraulic construction machine, such as a backhoe or excavator. The HIL testbed is a useful tool during rapid prototyping of control algorithms for the test valve, and for performing controlled experiments with the valve in the context of developing valve control algorithms to improve the overall energy efficiency of hydraulic systems. This paper discusses four key topics: the architecture of the real-time simulation and testbed control process, the modeling and validation of the emulated machine dynamics, the controller development for the HIL testbed, and some initial performance testing of the HIL testbed.
Effect of Reinforcement and Chills on the Tribological Behaviour of Al-12% Si/B4C Composite
Authors: Bharath Sai Kumar G. R. , Gopal Prakash S.
Published: August 2009

Effect of reinforcement on the wear behavior of Aluminium-12%Si(LM6) reinforced with Boron Carbide (B4C) particles (quantity from 3 to 12 wt% in steps of 3 wt%; size 40–80μm) was investigated by a computerized pin-on-disk wear test rig under dry sliding conditions. Mild steel chill was used. Castings were prepared using dry sand moulds and the reinforcement particles were introduced into the matrix using Vortex-Route Method. Test result showed that this MMC was greatly influenced by the reinforcement and chill. It was found that 9 wt% of B4C particles in Aluminium-12%Si (LM6) alloy exhibited the least wear rate. An attempt to evaluate the tribological properties of this MMC with respect to reinforcement, chill and microstructure is made.
Vertical Integration of Excel in the Thermal Mechanical Engineering Curriculum
Authors: Woodbury Keith A. , Taylor Robert P. , Huguet Jesse , Dent Troy , Chappell Joseph , Mahan Kenneth
Published: August 2009

Microsoft Excel is a ubiquitous tool used frequently by practicing engineers. A recent survey of alumni from The University of Alabama’s Department of Mechanical Engineering regarding software tools revealed that 100% of the respondents used Microsoft Excel regularly on their jobs, while a low percentage used standard packages such as ANSYS or MATLAB, and that none used software tools which had been bundled with textbooks. The spreadsheet environment offers a great platform for computation and organization of engineering work, and the Visual Basic engine allows for great extensibility of Excel through the development of special functions and add-in modules. This paper reports on a proof-of-concept project to implement sustained emphasis on Microsoft Excel in the thermal mechanical curriculum at The University of Alabama. Specific add-in modules for use in thermodynamic analysis and heat transfer analysis have been developed and are continually being refined. These add-in modules have been utilized in a sequence of courses Thermo I, Heat Transfer, Thermo II, and Energy Systems Design. Features of the add-in modules are detailed in this report and feedback from students and teachers are given.
Characterization of a New Titanium Dioxide-Polymer Nanocomposite Material for Electronic Packaging Using Light Scattering Spectroscopy
Authors: Dantal B. R. , Gupta S. , Saigal A. , Zimmerman M. A. , Georgakoudi I.
Published: August 2009

During the last decade there has been a great progress in the field of inorganic and organic hybrid material development and characterization techniques. Mechanical, optical and electrical properties of these hybrid materials heavily depend upon the percentage composition of inorganic and organic components of these hybrid materials [1–3]. Generally, inorganic particle distribution in the organic polymer is characterized using Scanning Electron Microscopy. In this paper we introduce an optics based technique for composite materials characterization. In our research, Titania pigments are used in molding compounds to improve opacity by increasing scattering efficiency of the medium. The light scattering efficiency of the samples is found to be increasing with the addition of Titania particles in the base polymer. This systematic increase of light scattering is attributed to the surface morphology, variation of refractive index due to addition of Titania particles.
Industrial Energy Audits via Thermal-Fluid System Design Course Projects
Authors: Pidugu Srikanth B. , Bayraktar Tuba
Published: August 2009

The staggering cost of energy has become a major challenge for industrial facilities in their constant effort to reduce product cost. For some manufacturing industries in the United States, the energy cost has even exceeded labor cost of their products. Staying viable in a world with a large appetite for energy resources depends on making energy efficient practices a part of day-to-day operation. Engineering programs need to prepare prospective engineers to become critical thinkers in the area of energy usage. This paper outlines the process of industrial energy audit projects conducted in senior level thermal-fluid design classes at the University of Wisconsin–Platteville (UWP) and University of Arkansas at Little Rock (UALR). In the frame of project work, each student team visited a local industrial facility, found out facility’s energy consumption data, identified and evaluated opportunities for energy saving. Total of eight projects were carried out for diverse manufacturing industries such as iron melting foundry, engine industry, aircraft and vehicle industries in Northeast Wisconsin and Central Arkansas. The energy audit reports included energy assessments of various systems such as fans, air compressors and compressed air lines, lighting, and motors. The energy audit reports also evaluated redesign of a large cooling water pipe network and design of a Rankine cycle to utilize the large amount of heat wasted during the iron melting process.
Percolation Effects on the Thermal Conductivity of 3D Nanotube Composites
Authors: Kumar Satish , Alam Muhammad A. , Murthy Jayathi Y.
Published: August 2009

We analyze thermal transport in three-dimensional (3D) nano-composites composed of carbon nanotube (CNT) dispersions to investigate percolation effects on the effective thermal conductivity of these composites. Thermal transport simulations for the randomly distributed nanotubes inside the host substrate are based on the diffusive Fourier conduction theory. The numerical model incorporates the effect of substrate-CNT conductivity ratio and the interfacial resistance due to tube-tube and tube-substrate contact, which are the most critical parameters governing thermal transport properties. Numerical predictions of effective thermal conductivity are in excellent agreement with the linear response theory and effective medium approximation (EMA) when assumptions of theory are incorporated in the model. The trends for the variation of effective thermal conductivity with increasing nanotube density are in broad agreement with previous experimental observations. Our numerical results also show that the onset of thermal percolation is gradual and largely dependent on the tube-to-substrate conductivity ratio and interfacial resistance at tube-tube and tube-substrate contact.
Research and Education With a Hydraulic Hybrid Vehicle Laboratory
Authors: Schroeder Christopher C. , Elahinia Mohammad H.
Published: August 2009

This paper presents the development of a hydraulic hybrid vehicle (HHV) based laboratory course for the Mechanical, Industrial, and Manufacturing Engineering Department at the University of Toledo. The objective of the laboratory course is to serve as both an educative tool as well as a tool in advancing the research of HHV technologies. The laboratory consists of a HHV test stand that approximates the workings of a series type HHV and an accompanying simulation model of the system. The course is based on a problem-solving learning approach that will aid students in gaining a fuller understanding of the fundamentals from core mechanical engineering curriculum including: Fluid Dynamics, Energy Systems, Vibrations, Mechatronics and Control. This course is unique in that the instructor serves a guide or manager for the students and does not evaluate the student based on exams rather, the student is evaluated based on his/her ability to apply engineering principles. After learning some basics of research and performing a literature review of the subject, the students will be asked to solve a problem and report their findings in a technical publication format. The students are evaluated based on their performance in applying engineering principles towards the solution of a relevant engineering problem and effectively communicating that via a conference publication candidate. In this way, a better index for evaluating student mastery of engineering principles is achieved and a gaping hole in the Mechanical Engineering curriculum is filled while at the same time offering an efficient means of advancing HHV technology.
Design, Dynamics and Active Control of Micro Interferometers for Low Noise Parallel Operation
Authors: Karhade Omkar , Degertekin Levent , Kurfess Thomas
Published: August 2009

Micromachined Scanning Grating Interferometer (μSGI) array offers a viable solution to the high resolution, large bandwidth, non-contact and high throughput metrology. Parallel active control of μSGIs is necessary to reduce the effect of positioning errors and ambient vibration noise. To achieve individual control of the μSGIs, the gratings in the μSGI are micromachined on Silicon membranes, which can be electrostatically actuated. These tunable gratings are designed to have sufficient range of motion (∼400nm) and sufficient bandwidth (∼50kHz) for effective noise reduction. The tunable gratings are fabricated successfully using Silicon on Insulator wafers with a two mask process. A novel recurrent calibration based control algorithm is designed to actively control the tunable gratings. The novel algorithm is implemented digitally using FPGA on an array of μSGIs simultaneously. The algorithm compensates for the non-linearities of the actuator and problem due to limited range of motion. A system model is built to design and analyze the control algorithm and is verified by experimental results. Experimental results show 100 times noise reduction at low frequencies and 6.5kHz noise reduction cutoff frequency. A resolution of 1×10−4 nmrms/√Hz is achieved by implementation of this algorithm on μSGI.
Flow Boiling Characteristics in a Fractal-Like Branching Microchannel Network
Authors: Liburdy J. A. , Pence D. V. , Narayanan V.
Published: August 2009

This study evaluates flow instability and void fraction in a fractal-like branching microchannel network. The flow network is characterized by set branching ratios for channel length and width of 1/2 and 2, respectively, and features five branching levels. The hydraulic diameter of the channels ranged from 308μm at the inlet to 143μm at the outlet. Test were performed using water heated to an 88°C at the inlet with a mass flow rate of 10g/min. Heat fluxes of 1.76 W/cm2 and 2.64 W/cm2 were applied to the test device for the given flow rate. An upstream control valve was used to throttled the flow with a pressure drop approximately 100 times larger than the pressure drop across the test device. For the cases with and without throttling results for inlet pressure oscillation frequency and vapor activity at the inlet of the test device are compared. In addition, time averaged void fraction is compared for each branching level with and without throttling and is compared to predictions from a 1-D model. Results show good agreement between model and experiments for the average void fraction although local values differ significantly.
Experimental Studies of Adiabatic Flow Boiling in Fractal-Like Branching Micro-Channels
Authors: Daniels Brian J. , Liburdy James A. , Pence Deborah V.
Published: August 2009

Experimental results of adiabatic boiling of water flowing through a fractal-like branching microchannel network are presented and compared to numerical simulations for identical flow conditions. The fractal-like branching channel network had channel length and width ratios between adjacent branching levels of 0.7071, a total flow length of 18 mm, a channel height of 150 μm and a terminal channel width of 100 μm. The channels were DRIE etched into a silicon disk and pyrex was anodically bonded to the silicon to form the channel top and allowed visualization of the flow within the channels. The water flowed from the center of the disk where the inlet was laser cut through the silicon to the periphery of the disc. The flow rates ranged from 100 to 225 g/min and the inlet subcooling levels varied from 0.5 to 6 °C. Pressure drop across the channel as well as void fraction in each branching level were measured for each of the test conditions. The measured pressure drop ranged from 20 to 90 kPa, and the measured void fraction ranged from 0.3 to 0.9. The pressure drop results agree well with the numerical predictions. The measured void fraction results followed the same trends as the numerical results.
A Remotely Accessed Flow Rig Student Laboratory
Authors: Dai Sumei , Aziz El-Sayed , Esche Sven K. , Chassapis Constantin
Published: August 2009

The movement of a fluid represents a fundamental phenomenon with many practical applications in a variety of engineering disciplines. The losses incurred in pipes, ducts and fittings and the characteristics of the corresponding fluid flow patterns are core subjects of undergraduate engineering courses in fluid mechanics. These courses are typically accompanied by laboratory components that aim to help the students in visualizing and understanding the complex theoretical concepts. Conducting hands-on experiments in undergraduate laboratory courses with large student enrollment imposes significant strains on the fiscal, spatial and personnel resources of the educational institutions. Therefore, virtual and remote laboratories are rapidly being adopted in engineering education across the globe as a compelling tool for enhancing the laboratory experience of students residing on campus as well as beyond the local campus. This paper will discuss some recent developments that were accomplished as part of a multi-disciplinary research project on online laboratories at Stevens Institute of Technology with funding from the National Science Foundation. Here, a remote laboratory setup is presented, which was developed by retrofitting a commercially available air flow rig with remote control and remote monitoring capabilities. The resulting system enables the students to access the experimental apparatus via the Internet in real time from anywhere at anytime and to conduct several laboratory exercises, including the calibration of a flow meter based on an orifice plate that is inserted into the air stream, the exploration of the flow development in a straight pipe and the determination of the free-flow velocity profile after the outlet. This remote experiment setup and/or a previously developed interactive virtual flow rig simulation module can be used in the laboratory part of the fluid mechanics course to complement hands-on experiments where the students are present in the actual laboratory facility.
Simulation of Phonon Transmission at Semiconductor Interfaces Using an Atomistic Green’s Function Method
Authors: Sun Lin , Murthy Jayathi Y. , Huang Zhen
Published: August 2009

An atomistic Green’s function method is applied to study phonon transport across interfaces between two semi-infinite semiconductors. We investigate the dependence of phonon transmission function on interface atomic configuration, roughness layer thickness and phonon frequency. The transmission function is obtained for a number of interface configurations, including Si/Ge/Si confined structures and a single Si/Ge interface. An interface with a regularly-patterned roughness is investigated to illustrate how the rough interface influences phonon transmission. The results show that the cutoff frequency and the local density of states are modified due to the rough interface. The transmission function is found to strongly dependent on the presence of atomic-scale roughness.
Nonlinear Control of a Belt Driven Two-Axis Positioning System
Authors: Zaki A. , Sollmann K. , Jouaneh M. , Anderson E.
Published: August 2009

XY-positioning is an important task in industrial applications. The improvement of the speed of positioning while keeping good accuracy can increase productivity and is therefore highly desirable. The studied H-frame system is a parallel XY-positioning device that uses a timing belt to transmit motion from two stationary motors. As a result, the system is capable of fast acceleration due to lower number of moving parts. However, the flexibility of the timing belts poses a problem when trying to move the positioning system at high speed. A dynamic model of the H-Frame system that accounts for the non-linear friction present in the system was developed and verified experimentally. This model was further used in simulation to develop a controller for the system. A collocated PD controller with friction compensation was designed and implemented experimentally on the system. Furthermore, results of the previous controller were compared to an adaptive PD controller. The adaptation algorithm involves changing the controller gains as a function of the tracking error without sacrificing the stability of the system. It was found that the adaptive PD controller is more suitable for positioning applications.
Modeling of Active Differential Dynamics
Authors: Deur Josˇko , Hancock Matthew , Assadian Francis
Published: August 2009

Active differentials are increasingly being used in high-end vehicles in order to improve the overall performance of vehicle dynamics control systems. The active differentials can be divided into active limited slip differentials and torque vectoring differentials. This paper presents the development of a generalized mathematical model of active differential dynamics using the bond graph modeling technique. Different levels of model complexity are considered, starting from a second-order model with lumped input and output inertia towards high order models including the gear inertia and halfshaft compliance. The paper also presents typical model simulation results and their comparative analysis with respect to drivability and time response features.
Computational Modeling of Dynamics of Single Bubbles Emanating From Capillary-Tube Orifice in an Isothermal Liquid Pool
Authors: Kasimsetty S. K. , Manglik R. M. , Jog M. A.
Published: August 2009

The growth dynamics (inception → departure) of isolated gas bubbles, emanating from a capillary-tube orifice submerged in isothermal pools of different liquids is computationally investigated. The complete set of continuity and transient Navier-Stokes equations are solved, and the gas-liquid interface during the bubble growth process is tracked using a volume of fluid (VOF) method. Computational solutions that describe the dynamic behavior — incipience, growth, and pre-departure necking — of a single bubble growing from tips of sub-millimeter-to-millimeter-scale capillary orifices in stagnant pools are presented. The parametric effects of liquid properties (surface tension and viscosity, in particular), capillary diameters, and air flow rates on the bubble shape, its equivalent diameter, and growth times are described. Furthermore, these results are shown to be in excellent agreement with the available experimental data, and they fundamentally highlight the ebullience structure and the role of liquid-gas interfacial tension on the bubble evolution.
Application of Diethyl Ether to Reduce Smoke and NOx Emissions Simultaneously With Diesel and Biodiesel Fueled Engines
Authors: Iranmanesh Masoud , Subrahmanyam J. P. , Babu M. K. G.
Published: August 2009

In this investigation, tests were conducted on a single cylinder DI diesel engine fueled with neat diesel and biodiesel as baseline fuel with addition of 5 to 20% DEE on a volume basis in steps of 5 vol.% as supplementary oxygenated fuel to analyze the simultaneous reduction of smoke and oxides of nitrogen. Some physicochemical properties of test fuels such as heating value, viscosity, specific gravity and distillation profile were also determined in accordance to the ASTM standards. The results obtained from the engine tests have shown a significant reduction in NOX emissions especially for biodiesel and a little decrease in smoke of DEE blends compared with baseline fuels. A global overview of the results has shown that the 5% DEE-Diesel fuel and 15% DEE-Biodiesel blend are the optimal blend based on performance and emission characteristics.
Two Dimensional Unsteady Laminar Flow of Power Law Fluids Past a Square Cylinder: A Numerical Study
Authors: Sahu Akhilesh K. , Chhabra Raj P. , Eswaran V.
Published: August 2009

The two-dimensional and unsteady flow of power-law fluids past a long square cylinder has been investigated numerically in the range of conditions 60 ≤ Re ≤ 160 and 0.5 ≤ n ≤ 2.0. Over this range of Reynolds numbers, the flow is periodic in time for Newtonian fluids. However, no such information is available for power law fluids. A semi-explicit finite volume method has been used on a non-uniform collocated grid arrangement to solve the governing equations. The macroscopic quantities such as drag coefficients, Strouhal number, lift coefficient as well as the detailed kinematic variables like stream function, vorticity and so on, have been calculated as functions of the pertinent dimension-less groups. In particular, the effects of Reynolds number and of the power-law index have been investigated in the unsteady laminar flow regime. The leading edge separation in shear-thinning fluids produces an increase in drag values with the increasing Reynolds number, while shear-thickening behaviour delays the leading edge separation. So, the drag coefficient in the above-mentioned range of Reynolds number, Re, in shear-thinning fluids (n < 1) initially decreases but at high values of the Reynolds number, it increases. As expected, on the other hand, in case of shear-thickening fluids (n > 1) drag coefficient reduces with Reynolds number, Re. Furthermore, the present results also suggest the transition from steady to unsteady flow conditions to occur at lower Reynolds numbers in shear-thickening fluids than that in Newtonian fluids. Also, the spectra of lift signal for shear-thickening fluids show that the flow is truly periodic in nature with a single dominant frequency in the above range of Reynolds number. In shear-thinning fluids at higher Re, quasi-periodicity sets in with additional frequencies, which indicate the transition from the 2-D to 3-D flows.
Effect of Upstream Shear on Flow and Heat (Mass) Transfer Over a Flat Plate
Authors: Ghosh Kalyanjit , Goldstein R. J.
Published: August 2009

A parametric study is conducted to investigate the effect of wall shear on a two-dimensional turbulent boundary layer. The shear is imparted by a moving belt, flush with the wall, translating in the flow direction. Velocity and mass transfer experiments have been performed for four surface-to-freestream velocity ratios (0, 0.38, 0.52, 0.65) with a Reynolds number based on the momentum thickness between 770 and 1776. The velocity data indicate that the location of the ‘virtual origin’ of the turbulent boundary layer ‘moves’ downstream towards the trailing edge of the belt with increasing surface velocity. The highest velocity ratio represents a case which is responsible for the removal of the inner region of the boundary layer. Mass transfer measurements downstream of the belt show the presence of a local minimum in the variation of the Stanton vs. Reynolds number for the highest velocity ratio. Downstream of this minimum, approximately 1 cm from the leading edge of the mass transfer plate, the characteristics of the turbulent boundary layer are restored and the data fall back on the empirical variation of the Stanton number with Reynolds number.
Implementation and Use of a Secondary Droplet Break-Up Model Under Diesel Engine Conditions
Authors: Dempsey Adam B. , Fiveland Scott B.
Published: August 2009

The diesel engine combustion process is very complex in nature. On the order of milliseconds, a high-pressure liquid spray is injected into a cylinder with a moving boundary. The spray undergoes break-up, dispersion, phase change and combustion. Accurate spray modeling is a prerequisite to modeling the diesel combustion process. Droplet break-up is governed by both primary and secondary break-up mechanisms. The Taylor Analogy Break-Up (TAB) Model was employed, in a self-contained simulation environment, to study the secondary break-up of a droplet flowing in a range of aerodynamic environments. The model, which describes the droplet distortion/break-up in an analogy to a spring-mass-damped system, was not formulated to solve the entire spray from start of injection to combustion, which is typically done with a PDF treatment. The developed simulation code provides a fundamental environment to parametrically study the effects of different break-up forcing functions (aerodynamic etc.) as well as provides the ability to refit power-law expressions that can then be used in phemonological diesel engine simulations. The paper first discusses the key physical mechanisms associated with breakup, the formulation/implementation of the numerical model, demonstrates its use to understand droplet parameter tradeoffs and how it can be used to construct reduced order break-up residence time models. Finally, the model is extended to a multi-DOF formulation to facilitate the understanding of the impact of additional breakup forces, which could be aerodynamic, collision-induced etc., on the droplet.
Integrating Lean Manufacturing and Six Sigma by Means of Axiomatic Design Principles
Authors: Jadeja Siddharth B. , Khandare S. S. , Batish Ajay , Patel Dipak
Published: August 2009

In the current era of globalization and liberalization, customer demands will continue to call for continuous quality improvement, coupled with cost reduction. Faced with ever increasingly competitive market, manufacturing firm must constantly make changes to improve their operations and besides that rejection rate of industry should be very less to offer the quality product at desirable cost. The small scale industry improvement became slow not because of less knowledge but due to the lack of the step by step guide to implement six sigma or lean manufacturing principles. There are numerous continuous improvement strategies available. However in this paper we present a concept for the integration of Lean Manufacturing principles and Six Sigma DMAIC methodologies with the help of FRs, DPs and PVs, the key elements of Axiomatic Designed templates. This paper is an attempt to provide a guideline for the specific required change or modification for the manufacturing systems in production and design process through a systematic structured approach by the means of AD to achieve the advantages of both called “Lean-Sigma”, endurance for small scale industry.
Thermal Accommodation Coefficients Between Nitrogen and Soot in Laser-Induced Incandescence Experiments
Authors: Daun K. J.
Published: August 2009

Time-resolved laser-induced incandescence demands detailed knowledge of the thermal accommodation coefficient, but to date little is understood about the gas/surface scattering physics underlying this parameter. We present a molecular dynamics (MD) simulation that models nitrogen molecules as rigid rotors and soot as crystalline graphite at 3000 K. A Monte Carlo integration over incident gas molecular speeds and surface atomic vibrational phases yields a simulated thermal accommodation coefficient that matches the experimentally-measured value. The MD simulation is then extended to assess how α changes with gas temperature, and finally to define a Cercingnani-Lampis-Lord scattering kernel.
Numerical Simulation of Turbulent Water Jet With Experimental Validation
Authors: Reedy Todd M. , Shoemaker Zachary M.
Published: August 2009

Many undergraduate and early graduate engineering programs offer courses in numerical analysis to teach students how to solve partial differential equations numerically and fluid mechanics to teach how the Navier-Stokes equations govern fluid phenomena. However, the connection between numerical analysis taught in the classroom and CFD is very rarely made. In an effort to bridge the gap, a simplified CFD simulation was developed to model the diffusion of a two dimensional turbulent water jet. Assumptions were made to simplify the Navier-Stokes equations in cartesian coordinates to arrive at a single PDE with only three terms. Considering that the modeled water jet is fully turbulent (Re ≈ 150,000), an algebraic turbulence model was incorporated to account for turbulent viscosity effects, namely Prandtl’s Mixing Length model. Velocity measurement and flow visualization were conducted using a water table to validate the model. Also, a commercially available CFD program (FLUENT) was employed to evaluate the validity of the simplifications made to the governing equations.
A Train Operations and Energy Simulator Model of the Steered Frame Truck
Authors: Wachsmuth John P. , Rosenberger G. Walter , Blank Robert W.
Published: August 2009

A Train Operation and Energy Simulator (TOES™) model was created in order to investigate the potential benefits of replacing three-piece trucks with the “Steered Frame Truck” currently under development. Loaded coal trains were simulated with three-piece trucks and with Steered Frame Trucks. Both trains were modeled traveling on Norfolk Southern’s Pocahontas division from MP V435 to V399. The consist and direction of travel are based on actual trains in service. It was found that the model predicts several benefits for replacing three-piece trucks with Steered Frame Trucks. These resulted from the Steered Frame Truck having a greatly reduced rolling resistance while traveling around a curve. The benefits were found to include: a significant reduction in fuel consumption, a reduction in in-train forces, and a small increase in average velocity. One drawback was also predicted: that the reduced rolling resistance would necessitate the increased use of air brakes while traveling down-hill. Although Steered Frame Trucks should produce a considerable reduction in lateral forces, modeling such a reduction was beyond the scope of this work. Similarly, modeling other potential benefits not directly derived from the Steered Frame Truck’s reduced rolling resistance was not considered here.