bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of the Convection Heat Transfer Coefficient for a Two-Dimensional Wall Jet: Uniform Temperature and Uniform Heat Flux Boundary Conditions
Authors: AbdulNour R. S. , Willenborg K. , McGrath J. J. , Foss J. F. , AbdulNour B. S.
Published: March 2022

The local heat transfer coefficients for isothermal and uniform heat flux boundary conditions for a two-dimensional wall jet have been experimentally determined. Hot wire anemometry surveys were used to quantify the velocity field in the wall jet. A micro thermocouple was used to quantify the temperature field in the wall jet for the isothermal boundary condition. Infrared imaging was applied to measure the wall temperature for the uniform heat flux boundary condition. The difference in the local convection coefficients due to the different thermal boundary conditions was largest at the leading edge of the heated wall and decreased in the stream wise direction. The local convection coefficient was found to be insensitive to the thermal boundary condition in the more turbulent region of the wall jet.
Facility for Calibrating Heat Flux Sensors in a Convective Environment
Authors: Holmberg D. , Steckler K. , Womeldorf C. , Grosshandler W.
Published: March 2022

The National Institute of Standards and Technology (NIST) presently conducts heat flux sensor calibrations using standard radiation methods. In practice, however, many heat flux sensors are used in test environments where convective heat transfer dominates. Equivalent fluxes in radiation or convection can produce different sensor responses due to sensor surface properties (e.g., emissivity, roughness) and near-surface structure (e.g., transmissivity, temperature distribution). These issues are being addressed at NIST by the development of a convective heat flux facility. By extending calibration capabilities to include a primarily convective environment, direct comparisons of sensors in controlled convective and radiative environments will be possible.

This report describes the progress of the convective heat flux calibration facility under development at NIST. A low-speed wind tunnel has been built to produce a boundary layer shear flow above a constant temperature copper plate. Independently controlled heaters and temperature monitoring systems have been designed and installed to provide an isothermal surface with a known reference heat flux. Wind tunnel configuration and test section instrumentation details, as well as characterization of the flow and the temperature distribution in the plate, are described. Initial heat transfer measurements and results from numerical modeling efforts and hot-wire anemometry are reported.
3-D Convection in 2-D Boundary Layers: First Progress Report
Authors: Eaton John K. , Mukerii Debiit , Moffat Robert J. , Batchelder Keith A.
Published: March 2022

Experiments are under way to investigate the effect of spanwise thermal diffusion within the boundary layer on the convective heat transfer rate from a small heated spot under a hydrodynamically two-dimensional boundary layer. If there is a significant effect, this would require a correction to the readings from small heat flux gages whenever the gage temperature differs from the surrounding wall temperature. This correction would be in addition to the known effect of a step change in wall temperature on the local heat transfer rate.

This note describes the hypothesis which underlies the test plan, the apparatus, and some preliminary qualification test results. No definitive data are presented.
Radiation Effects on Laminar Mixed Convection in an Inclined Square Duct
Authors: Yan Wei-Mon , Li Hung-Yi
Published: March 2022

A numerical calculation has been performed for the simultaneously developing laminar mixed convection flow and heat transfer for a gray fluid in an inclined square duct with radiation effects. The discrete ordinates method is employed to solve the radiative transfer equation. The coupled momentum and energy equations are solved by the Du Fort-Frankel numerical scheme. In this paper, the major independent parameters are the modified Rayleigh number, mixed convection parameter, conduction-to-radiation parameter, optical thickness, single scattering albedo and wall emissivity. The influences of these parameters on the developments of velocity, temperature, friction factor and Nusselt number are investigated in detail. The axial variations of the fRe and Nu are characterized by a decay near the entrance due to the entrance effect, but the decay is attenuated by the onset of secondary flow. The results for axial distributions of Nusselt number indicate that heat transfer is enhanced by the presence of radiation, but the thermal buoyancy effect is reduced. In addition, the influences are more significant when the conduction-to-radiation parameter and single scattering albedo decrease or the optical thickness and wall emissivity increase.
Closed-Form Solution of Temperature and Heat Flux in Embedded Cooling Channels
Authors: Griggs S. C. , Haji-Sheikh A.
Published: March 2022

An analytical method is discussed for predicting temperature in a material layer with embedded cooling channels to control material temperature. Problems of this type are encountered in the aerospace industry and include high-temperature or high-heat-flux protection for advanced composite-material skins of high-speed air vehicles, thermal laminar flow control on supersonic civil transports, or infrared signal suppression on military vehicles. A Green’s function solution of the diffusion equation is used to simultaneously predict the localized and global effects of temperature in the material and embedded cooling channels. The integral method is used to calculate temperature in the cooling fluid and material simultaneously. This method of calculation preserves the three-dimensional nature of this problem.
Three-Dimensional Natural Convective Flow About a Melting Horizontal Ice Cylinder
Authors: Oosthuizen P. H. , Xu Z.
Published: March 2022

There is some experimental evidence that the flow around a melting ice-cylinder with a large length-to -diameter ratio placed in a large tank of water may not be two-dimensional. The existence of such a three-dimensional flow and the nature of the flow have been experimentally investigated in the present study. Ice-cylinders with a length of 0.5 m and an initial diameter, in most tests, of 53 mm were used. These cylinders were formed from water that contained a small amount of food coloring. The cylinders were suspended horizontally in a large clear plexiglas tank containing water. As the ice cylinders melted, dyed water was released into the flow allowing the flow pattern near the cylinder to be observed. Test were undertaken with the temperature of the water in the tank near room temperature and with the temperature of this water near 4°C. In all cases, it was found that the plume flowing from the ice-cylinder was not a uniform colored sheet as it would be if the natural convective flow about the cylinder was two-dimensional. Instead, this flow was highly three-dimensional, consisting of a series of distinct vortices with axes in the direction of the plume flow. The nature of this flow and the effect of the water temperature on it have been studied.
Unsteady Laminar Thermal Boundary Layer on a Spinning Permeable Isothermal Body
Authors: Kahveci Kamil , Ece Mehmet Cem
Published: March 2022

The initial laminar thermal boundary-layer flow past an impulsively started translating and spinning rotational symmetric, permeable isothermal body is investigated. Velocity components and temperature are expanded in series in powers of time. Leading, first and second order functions are obtained analytically and the third, forth and fifth order functions are determined numerically. Application of the general results to a sphere shows that the unsteady flow field displays complex patterns. Surface blowing is observed to aid body spin in facilitating flow separation. Surface heat flux is enhanced near the front stagnation point and in the reversed flow region and reduced around the point of separation. Surface suction is found to increase the heat transfer while surface blowing decreases it.
A Numerical Study of Three-Dimensional Natural Convection in a Horizontally Heated Enclosure
Authors: Oosthuizen Patrick H.
Published: March 2022

Flow in a rectangular enclosure with a square horizontal cross-section, whose lower horizontal surface is heated and whose upper horizontal surface is cooled and whose vertical side-walls are adiabatic, has been numerically studied. It has been assumed that the flow is laminar and that the fluid properties are constant except for the density change with temperature which gives rise to the buoyancy forces. The unsteady form of the governing equations, written in terms of the vector potential and vorticity vector functions and expressed in dimensionless form, have been solved using a finite-difference procedure based on the equations. The solution was started with no flow in the enclosure. The solution, in general, has the following parameters: The Rayleigh number Ra, the Prandtl number and the size A of the square cross-sectional shape compared to the height of the enclosure. Results have only been obtained for a Prandtl number of 0.7. Results for values of A between 1 and 4 for various relatively low values of Rayleigh number (up to 15000) have been obtained. The results have been used to determine the effect of A on the value of Ra below which there is no fluid motion in the enclosure and to examine the various flow patterns that arise as the value of Ra is increased. The effect of A on the variation of the mean Nusselt number with Ra has also been examined.
Development of a Grid Partial Analytical Solution Method for Solving the Moving Source Heat Conduction Problem
Authors: Ouyang Xing , Bishop Patricia J.
Published: March 2022

The grid partial analytical solution method is a newly developed unconditionally stable explicit numerical solution method for solving parabolic partial differential equations. This method discretizes only the spatial domain and predicts a continuous time dependent function at each spatial nodal point. As such, instead of conventionally predicting the solution from a number set, this method predicts from a functional domain. The typical properties of the grid partial analytical solution method can be summarized as the following:

(1) It predicts a continuous nodal time dependent function rather than a discrete nodal value.

(2) The prediction is unconditionally stable. And unlike any other unconditionally stable finite difference schemes which will lose accuracy when Fourier number becomes large, the proposed method allows single step time marching and unlimited reduction in the spatial step size Δx.

(3) For a fixed time step, the higher value of the grid Fourier number resulting from decreasing Δx, the higher the accuracy is achieved in the predicted solution.

(4) The grid partial analytical solution converges uniformly to the full analytical solution as the spatial truncation error is infinitely decreased by reducing the spatial step size Δx.

This unique characteristic of the analytical treatment of time also makes it possible to treat other time dependent nonhomogeneities involved in heat conduction problem analytically. In this paper, a moving source heat conduction problem is posed and its grid partial analytical solution method developed.
Digital Micromirror Device™: Commercialization of a Massively Parallel MEMS Technology
Authors: Hornbeck Larry J. , Howell T. Russ , Knipe Richard L. , Mignardi Michael A.
Published: March 2022

The Digital Micromirror Device™ (DMD™) is an optical, massively parallel microelectromechanical systems (MEMS) technology that has 500,000 to 1,300,000 rotating digital micromirrors monolithically formed over a CMOS address circuit. Each micromirror acts as a digital light switch. The DMD is the only MEMS light modulator technology to be commercialized in a projection display application. Because the DMD is digital and has numerous moving parts, the commercialization process has had its unique challenges and rewards. This paper introduces DMD technology and presents its R&D history and current focus. The quality, reliability, and manufacturing challenges of this important new display technology also are presented, along with the factors that led to the successful resolution of these challenges.
A High-Sensitivity Micromachined Accelerometer Based on Electron Tunneling Transducers
Authors: Liu C. H. , Reynolds J. K. , Partridge A. , Grade J. D. , Barzilai A. M. , Kenny T. W. , Rockstad H. K.
Published: March 2022

This paper describes the design, fabrication, modeling, and early testing of a new high-sensitivity bulk-silicon micromachined accelerometer based on electron tunneling. The electron tunneling transducer permits detection of small displacements of the proof mass with high electrical response; such a transducer is essential for a high-performance miniature accelerometer. Using bulk-silicon microfabrication technology, a new tunneling accelerometer has been fabricated successfully and operated reliably. The resonant frequency of the proof mass in this tunneling accelerometer is easily modified to satisfy different requirements of sensitivity, dynamic range and bandwidth. This tunneling accelerometer is designed for underwater acoustic application and can be packaged in an 8 cm3 volume with a mass of 8 grams. The measured sensitivity is as high as 200 V/g with a resolution of less than 10 μg/Hz, which is limited by environmental noise, from a few Hz to 270 Hz for a 360 Hz resonant proof mass.
Mechanical Testing of Thicker MEMS Materials
Authors: Sharpe William N. , LaVan David A. , McAleavey Andrew
Published: March 2022

Techniques are described for recording the complete stress-strain curve of nickel microspecimens that are 3 millimeters long and 0.2 millimeters thick and wide. These specimens are fabricated by electrodeposition using the LIGA technique and are typical of the material that would be used in larger microelectromechanical systems (MEMS). Pure nickel deposited in this manner has a yield stress on the order of 300 MPa in contrast to the value of 60 MPa for the bulk material.
The Minimum Meniscus Radius and Capillary Heat Transport Limit in Micro Heat Pipes
Authors: Ma H. B. , Peterson G. P.
Published: March 2022

Based on the momentum conservation and Laplace-Young equations, an analytical expression for the minimum meniscus radius was derived and an expression for the maximum capillary heat transport limit in micro/small heat pipes was obtained. These expressions incorporated the shear stresses at the liquid/solid and liquid/vapor interfaces, contact angle effects, vapor pressure drop, tilt angle, groove dimensions, and channel angle effects. In order to verify the expressions derived herein, comparisons with experimental data from triangular grooves and micro heat pipes were made and demonstrated that these equations can be used to predict the maximum capillary heat transport in the micro/small triangular grooves or micro heat pipes with a higher degree of accuracy and better explain the behavior than previously developed models.
Parabolic Flight Experiments of Spray Cooling With Water and FC-72 Under Reduced and Elevated Gravity
Authors: Yoshida Ken-ichi , Kato Takahisa , Oka Toshiharu , Abe Yoshiyuki , Mori Yasuhiko H. , Nagashima Akira
Published: March 2022

This paper reports on the authors’ latest parabolic-flight experiments (November 1996) of spray cooling. Water and FC-72 (perfluorocarbon) were employed alternately as a test liquid sprayed from a single full-cone nozzle onto a Cr-plated surface of an electrically heated copper block (transient cooling experiments) or onto a transparent In2O3-coated surface of a glass block (steady state experiments in a relatively low superheat region). Each experimental run was accomplished during some 15 seconds through which a reduced gravity condition (∼0.01 times the terrestrial gravity) or an elevated gravity condition (∼2 times the terrestrial gravity) was maintained in the laboratory used — the cabin of an MU-300 aircraft. Cooling curves over a wide range of wall-superheat were obtained with water sprayed at significantly different volume fluxes and with FC-72 sprayed at rather low volume fluxes. It is demonstrated that the gravity dependency of the spray cooling characteristics varies with the spray volume flux and the impinging droplet velocity. Qualitative interpretations of the observed gravity dependency are provided.
Optimization of a Cooling Tower With Ozonation Based on Exergy
Authors: Lu Sun-Shing , Wong Kau-Fui V. , Stoff Larry
Published: March 2022

Cooling tower water treatment is necessary because water has dissolved materials that can deteriorate the operation of the cooling tower. In addition, bacteria in the water can be scattered into the air-conditioned area that can harm people. The first known case of the outbreak of the fatal Legionnaire’s disease in 1976 manifested this fact. There are several methods used in treating cooling water. The application of chemical water treatment is considered mainstream at present, however, its practice is under scrutiny because of environmental considerations. Water treatment with ozonation is selected because it is effective. It is relatively new and thought to be the least controversial of the “new” methods. Other “new” methods include magnetic and electrostatic method, etc. Additionally, many papers and reports have shown that ozonation not only cleans water but also reduces water and power consumption. This is very important especially in places where water and energy resources are not sufficient.

The purpose of this paper is to perform an analysis on cooling tower water treatment according to the first and second law of thermodynamics (exergetic analysis), and try to optimize its operating conditions. The exergetic analysis is better than energetic one because it gives a clearer explanation of the performance, in particular, it takes into consideration the impact of the system on the environment.
Incorporating a District Heating/Cooling System to an Existing Geothermal Power Plant
Authors: Kanoglu Mehmet , Çengel Yunus A. , Turner Robert H.
Published: March 2022

Geothermal energy has been used for power generation, space and process heating, and to a lesser extent, space cooling. However, it is rarely used for cogeneration. This paper shows how a district heating/cooling system can be incorporated to an existing geothermal power plant to make the best use of extracted hot brine.

In the power plant analysis, exergy destruction throughout the plant is quantified and illustrated using an exergy cascade. The primary source of exergy destruction in the plant is determined to be the reinjection of used brine into the ground, which accounts for 48.1% of the total exergy destruction. The overall first and the second law efficiencies of the plant are calculated to be 5.6%, and 28.3%, respectively, based on the exergy of the geothermal fluid at downwell, and 5.7%, and 28.6%, respectively, based on the exergy of the geothermal fluid at wellhead.

A binary system is considered for the heating/cooling district to avoid corrosion and scaling problems. The heating system as designed has the capability to meet the entire needs of the Reno Industrial Park under peak load conditions, and has 30% reserve for future expansion. An absorption system will be used for the cooling of the intended 40% floor space of the industrial park. An economic analysis shows that the incorporation of the district heating/cooling system with 2,785,000 m2 of floor space connected to the geothermal grid appears to be feasible, and financially very attractive. Further, using the returning fresh water from the district heating/cooling system for partial cooling of the binary fluid of the power plant can save up to 15% of the fan work.
The Feasibility of Using a Septic Tank as a Heat Source for Geothermal Heat Pumps
Authors: Hanegan Traci , DenBraven Karen
Published: March 2022

A geothermal heat pump system with three ground coils was installed in a residence on Lake Coeur d’Alene in northern Idaho. A portion of the ground heat exchanger in this system is wrapped around the residential septic tank. The primary purpose of this research was to examine the feasibility of using septic tanks as a heat source for geothermal heat pumps using experimental data collected from this site.

Ground temperatures around this septic tank averaged between −3.5°C and 1.0°C during the 1995–96 heating season. This septic tank is located such that there is little soil surrounding it on all sides. Ground temperatures around the septic coil were influenced more by the outside air temperature than were the other two coils. There was no evidence of the septic tank freezing up or failing to properly function.

Utilizing a septic tank as a heat source for GHP systems is feasible design option if the septic tank is used on a full-time basis. However, the tank should be surrounded on all sides by a large amount of soil and/or insulated from the ground surface to ensure that ground temperatures near the tank remain warm, especially during the cold winter months.
An Analysis of the Major Variables Impacting Performance of Absorption Chillers and Heat Pumps
Authors: Herold Keith E.
Published: March 2022

The major irreversibilities in absorption heat pump technology are associated with the transfer of heat into and out from the machine. By modeling only these irreversibilities, a model is formulated that provides significant insight into the thermodynamics of such cycles. In particular, the shape of the COP curve as a function of heat input temperature does not follow the intuition developed from a fully reversible model. Such a fully reversible model predicts that the COP should rise with the heat input temperature. Instead, the COP of an actual absorption machine falls with a rise in heat input temperature. The explanation of this detail clarifies a number of aspects of the technology and provides insight into such questions as what performance can be expected from future advanced cycles. The model developed here is internally reversible but includes the irreversibilities associated with the external heat transfer processes. Observations made from the model are compared against experience with actual absorption systems to arrive at several generalizations that are useful for absorption machine design.
Effects of Evaporator Frosting on the Performance of an Air-to-Air Heat Pump
Authors: Martínez-Frías Joel , Aceves Salvador M.
Published: March 2022

This paper investigates the effects of frost formation on performance for an air-to-air heat pump. A transient model is used for evaluating frost formation on a parallel-plate heat pump evaporator. The frost formation model is derived by applying the equations of conservation of mass, momentum and energy, as well as some empirical correlations, to calculate the growth and densification of the frost layer. The model has been validated in a previous work by comparison with experimental results.

In this paper, the frost formation model is incorporated into the evaporator subroutine of an existing heat pump model to calculate performance losses due to frosting as a function of weather conditions and time of operation since the last evaporator defrost. The heat pump model takes into account the performance losses due to added pressure drop and heat transfer resistance that result from the growth of the frost layer.

The results show frost formation parameters and heat pump COP as a function of time and ambient conditions. It is determined that there is a range of ambient temperatures and humidities in which frosting effects are most severe, and this range is explored to calculate heat pump operating conditions. The heat pump analysis results are expected to be useful in predicting optimum defrosting conditions, and to evaluate alternative methods for defrosting.
Pool Boiling Heat Transfer Coefficients of Alternative Refrigerants
Authors: Jung Dongsoo , Kim Chong-Bo , Song Kil-Hong , Lee Jun-Kang
Published: March 2022

Nucleate pool boiling heat transfer coefficients (HTCs) of 14 refrigerants are measured from a 19mm o.d. plain copper tube heated by a cartridge heater. All measurements are carried out in the pool temperature of 4∼25°C and in the heat flux of 10∼80kW/m2. Test results show that HTCs of R32, R125, R143a, R152a, and R410A are higher than those of R22. Especially, R32 showed the highest HTCs among all the refrigerants tested. As for R22 alternatives, HTCs of R410A are 50% higher than those of R22 while those of R407C are very similar to those of R22. It is also found that some of the popular pool boiling heat transfer correlations in the literature failed to predict the HTCs of newly developed alternative refrigerants. Hence, a dimensionless analysis is carried out in an attempt to develop a general correlation for all HTCs of pure refrigerants. Thus developed correlation showed an excellent agreement with all experimental data showing a mean deviation of 5.5%.
Approximating Wave Guide Geometries in Gas Pulsation Modeling
Authors: Lai Peter C.-C. , Soedel Werner
Published: March 2022

The four pole concept has been used to analyze gas pulsations in acoustic cavities for a long time. In this study, the four pole parameters for one dimensional (1-D) to three dimensional (3-D) cavities are applied to model a real compressor head with irregular corners and flow obstacles, and a bullet shaped muffler by the idealized rectangular box and circular cylinder approximations. The theoretical results of the transfer functions are calculated from four poles and compared to the experimental data. The comparisons show that certain response frequencies shift between idealized theory and experimental data due to the limitations of an idealized shape analysis for practical applications. In addition, the anechoic termination assumption, which is usually used in compressor discharge modeling, is discussed in this paper. The transfer functions of the above muffler model with different discharge pipe lengths and damping, and horn shaped pipe are simulated and compared. The results represent the typical data measured from experiments.
Prediction of Flow and Heat Transfer Within a Scroll Compressor Working Chamber
Authors: Zhu J. , Ooi K. T.
Published: March 2022

A numerical investigation has been carried out to predict the fluid flow and heat transfer within a scroll compressor working chamber. The “two-boundary” algebraic method was employed to generate the curvilinear and deforming grid systems which can accommodate a range of practical scroll compressor configurations. The computation accounts for the effect of simultaneous change in the instantaneous volume and the moving boundary of the scroll chamber. The convective heat transfer has been calculated through standard k-ε turbulence model with log-law wall function. Fluid flow and heat transfer rate were predicted in consecutive time steps. Results obtained were compared with that predicted using the lumped parameter approach employing the First Law of Thermodynamics, where some commonly used heat transfer empirical correlations were employed. The comparisons show that empirical correlations are inadequate in predicting heat transfer within the scroll compressor chamber. This is due to highly curved geometry of the scroll chamber and results in the existence of the recirculating flow especially in the late period of the compression process. However, reasonably good prediction in pressure history can be obtained using the First Law of Thermodynamics.
Dynamic Simulation of Bearing Forces in Screw Compressors
Authors: Adams Glynn P. , Qin Zhaohui
Published: March 2022

In most current investigations on bearing forces in screw compressors, the supports at the bearings are basically treated as ideal, simply supported boundary conditions [Adams and Soedel, 1995; Qin and Adams, 1996; You et al, 1994]. By using static mechanics, the loads on the rotors are resolved to equivalent loads at the bearings at suction and discharge ends. Studies on rotor dynamics have shown that the characteristics of a rotor bearing system are strongly dependent on thebearings that support the rotor. Therefore, it is important to study the rotor dynamic performance of screw compressors so that the bearing faces can be more accurately described. In this paper, a dynamic model of a rigid compressor rotor supported by two cylindrical roller bearingsand a four point contact ball bearing is developed from basic principles. This model is used to simulate the dynamic response of a typical screw compressor configuration. Under compression loads, the resulting bearing forces in the screw compressor are compared with those obtained by assuming ideal simply supported boundary conditions at the bearings. A more accurate model of the compressor response is believed to be obtained by coupling the global rotor motion with the local dynamics of nonlinear bearings.
Fast Estimation of Space-Time Correlations of Wall Induced Loads on a Cylinder by a Random Acoustic Plane Waves Field: Numerical and Experimental Application to the Supersonic Jet Noise of a Space Launcher During Lift-Off
Authors: Guillermin Bruno , Cléro Franck
Published: March 2022

The computation of the wall induced loads on a cylinder by random acoustic waves is often costly. In order to reduce this duration, an approximated model of diffraction has been developed on the basis of the scattering of a plane wave by an infinite cylinder. It leads to simplified expressions of the power spectrum density and the normalized cross-spectrum density, which are functions of the azimuth of the incident wave and of a non-dimensional variable β = k a sin(θ). This model gives excellent results as in the case of the infinite cylinder, as in the one of finite slim bodies. It has been linked to a jet noise sources model to allow an experimental validation in the complex case of a three engines launcher at lift-off. The results point out a satisfactory level of accuracy in different configurations, as on the amplitude, as on the phase.
Reverberation Room Survey and Qualification According to ASTM C 423
Authors: Hastings Mardi C. , Godfrey Richard D.
Published: March 2022

Results of an experimental performance qualification of a large reverberation room in the Noise and Vibration Control Laboratory at Owens-Corning Science & Technology Center, Granville, Ohio, are reported. The qualification testing was done according to ASTM C 423 – 90a and a proposed revision of ASTM C 423 being developed by Task Group E–33.01–D of ASTM Committee E–33 on Environmental Acoustics. The proposed revision puts requirements on spatial uncertainties in the reverberant field in addition to the uncertainty in the total number of decay rate measurements. Results of the performance qualification show that this room meets or exceeds requirements for a reverberation chamber for measurement of sound absorption and sound absorption coefficients in the 100 to 5000 Hz third-octave bands.
On Calibrated Measuring Microphones and Their Use in Ordinary Sound Fields
Authors: Peppin Richard J. , Hellsund Hans
Published: March 2022

Measuring microphones come with frequency response curves based on pure tone excitation in well-defined sound fields. Hence microphones have a distinct frequency response curve only for well-defined conditions. These conditions may, in fact, not be met in practice.

People making measurements infrequently use microphones in sound fields that are characterized and known, much less well defined. The location of the sound, the types and effects of reflections, and the exact relationship between the source and microphone are unknown. Hence the data taken may have unknown and unaccounted-for errors.

This paper presents the results of a study that compares the performance of microphones in ordinary and frequently encountered sound measurement situations. These situations consist of a combination of a number of sources, a variety of spaces, and a selection of microphone orientations. In other words, the measurements were made in non-ideal spaces. It is shown that the frequency response of a given measurement in an unknown field is unpredictable for whatever standard microphone used. The continuing efforts to tighten the specifications of instrument tolerances given these real-world errors will not improve reliability of measurements for many situations.
Analysis and Characterization of Ply Lay-Up in Fiber Reinforced Composites Using Ultrasonic Plate Wave Dispersion Curves
Authors: Rao Navin S. , Balasubramaniam Krishnan
Published: March 2022

In this paper, initial efforts on the characterization of the ultrasonic oblique incidence data to obtain the fiber orientation and ply Lay-up properties of orthotropic symmetry material systems, such as fiber reinforced composites, will be discussed. The acoustical data domain used was the plate wave dispersion curves. The influence of ply-Lay-up ordering in cross-ply symmetric graphite/epoxy laminates on leaky plate wave dispersion curves was studied. The Thomson-Haskell Method was implemented to model the reflection factor behavior of fluid-loaded laminated plates and compute the dispersion curves. Two different types of ply ordering — staggered and inverted — were examined. It was found that the all dispersion modes are sensitive to changes in lay-up sequence. Consequently, it was concluded that stacking sequence identification from leaky plate wave dispersion data is indeed possible, provided accurate experimental and robust combinatorial optimization techniques are used. It is further recommended that Genetic Algorithms can be used as the optimization tool for solving the inverse problem of nondestructively obtaining the ply-Lay-up from experimental oblique incidence ultrasonic data on composite materials.
Evaluation of Elastic Properties of a Functionally Graded Composite Using an Elastic-Impact Technique
Authors: Marur Prabhakar R. , Tippur Hareesh V.
Published: March 2022

An experimental technique for evaluating the elastic properties of functionally graded materials (FGM) is proposed. Ultrasonic pulse-echo measurements in conjunction with elastic impact testing permit determination of Young’s modulus, Poisson’s ratio and their longitudinal variation. The details of the formulation of the technique and the implementation issues are discussed in this paper. These techniques have been applied successfully to evaluate the properties of a unidirectionally graded glass-epoxy particulate composite.
Circular Expansion Chambers With Offset Inlet/Outlet
Authors: Selamet A. , Ji Z. L. , Radavich P. M.
Published: March 2022

The acoustic attenuation performance of circular expansion chambers with offset inlet/outlet pipes is investigated. Two approaches are employed to determine the transmission loss: (1) the three-dimensional computational solution based on the boundary element method (BEM); and (2) experiments on an extended impedance tube setup with expansion chambers fabricated with fixed inlet, outlet and chamber diameters, and varying chamber length to diameter ratios for the different relative locations of the inlet/outlet. The results from the two approaches are shown to agree well. The effect of multi-dimensional propagation is discussed in comparison with the classical treatment for the breakdown of planar wave.
Numerical Methods for Modeling and Optimization of Noise Emission Applications
Authors: Guisset Pierre , Tzannetakis Nikolas
Published: March 2022

This paper presents a unique methodology for applying Numerical Optimization, design of Experiments and Response Surface Model Techniques in conjunction with Finite Element and Boundary Element Models to solve acoustic radiation and transmission optimization problems. Implementations of numerical optimization algorithms, and the finite and boundary element methods along with global design sensitivities are presented. Finally two applications from the automotive industry demonstrate the methodology.
Prediction of Sound Radiation From Vibrating Structures in Motion: Application to Vehicle Pass-By Noises
Authors: Zhou Zhiwei , Wu Sean F.
Published: March 2022

This paper presents an extended Kirchhoff integral formulation for predicting sound radiation from an arbitrarily vibrating structure moving along an infinite baffle. In deriving this integral formulation, the effect of sound reflection from the baffle is taken into account by using the image source theory. Moreover, the effect of source convection motion and that of interaction between motion-induced turbulence and the vibrating surface on the resulting acoustic pressure field are incorporated in the formulation. As an example, this formulation is used to simulate sound radiation from a full-size vehicle driving on an infinite solid ground at various speeds. Sinusoidal forces are assumed to excite the vehicle on its four tires. Vibration responses due to these excitations are calculated using finite element method. Once the normal component of the surface velocity is specified, the radiated acoustic pressure field is obtained numerically using boundary element method. The results show that the effect of source convection motion becomes obvious when the Mach number exceeds 0.1, or equivalently, when a vehicle drives at a speed of 70 mph or higher.
Acoustic Prediction of Sound Insulation Panels Using Asymptotic and Numerical Solutions
Authors: Zhu Jason J. , Coats Timothy J.
Published: March 2022

This paper discusses the basic mechanisms of wave propagation inside sound insulation system based on one modified Biot theory. In particular, this paper concentrates on the determination of the asymptotic solutions to resonance frequencies and on the explanation of the interaction between the structural wave and acoustic wave. Finally, this paper demonstrates a numerical example for simulating sound transmission loss of a three-layer sound insulation system by using SYSNOISE/VIOLINS and compares it with the asymptotic solutions.
A Multi-Purpose Laser Sensor for Cutting Tools
Authors: Ryabov Oleg , Mori Kazuo , Kasashima Nagayoshi
Published: March 2022

This paper presents the application of a laser displacement meter for direct multi-purpose sensing of milling tool conditions. Using a laser displacement meter, a laser beam is projected onto the cutting tool and subsequently reflected. The intensity as well as the angle of the reflected beam are measured. The signals are interpreted for identification of tool geometry, tool whirling, or vibration. Signal processing and analysis depend on the application. A prototype system has been developed to demonstrate the feasibility of various applications, namely, (1) tool setting evaluation, (2) in-process measurement of milling cutter geometry and detection of tool failure, (3) continuous monitoring of milling cutter deterioration, (4) detection and measurement of chatter in milling, (5) measurement of milling tool bending and (6) thermal expansion.
Open Architecture Modular Tool Kit for Motion and Machining Process Control
Authors: Erol N. A. , Altintas Y.
Published: March 2022

An open, reconfigurable and modular monitoring and control system is presented for CNC machine tools. The CNC operating system is a fully integrated an open real-time, preemptive DSP operating system and a Windows NT application. It has vendor neutral architecture, and supports multiple DSP boards and multiple host computers for distributed operation. The system’s transparent communication protocol allows connection between software modules on the same or different DSP boards and host computers. The connections can be set up at runtime via a scripting language. The operating system allows modular integration of new functions developed in C language, and can be reconfigured to control robots, machine tools or processes, using simple script commands. The system can be used as an open architecture, modular operating system for the progressive development of real time signal processing, motion and process control applications running in WINDOWS NT and DSP environments. Sample applications for machine tool control and sensor assisted machining applications are presented.
Prediction of Quasistatic Errors in Three-Axis CNC Machining Centers
Authors: Chen Xiong-Biao , Geddam Aseervadam
Published: March 2022

Quasistatic error sources, which include thermal, mechanical loading and geometric error sources, are responsible for a very large proportion (typically, 70%) of the volumetric errors of a CNC machine tool. This paper discusses the development of a general quasistatic error model for multi-axis CNC machining centers using rigid body kinematics. To predict the quasistatic errors at any position in the workspace, a new method was proposed using the meshing concepts developed in the FEM literature. Finally, the spatial rate of change of the error was analyzed. The model and analysis method can be used as the basis of a compensation scheme as well as in budgeting of errors on a machine tool.
Application Specific Calibration of AE Sensors for Machining Monitoring
Authors: Hundt W. , Scheer C.
Published: March 2022

Monitoring of machining processes by the use of acoustic emission (AE) is a common technique. But the relation between the measured AE signal and the machining process is often not obvious. Here we present a method for the determination of the transfer function of the complete signal path between AE source and monitoring device. The signal acquisition system including the AE sensor can thus be “calibrated”, which allows the scaling of the measured signal in physically interpretable units. The method is specially adapted to the situation found in monitoring of machining, where the sensor position is fixed and the signal path is therefore kept constant.
Automatic 5-Axis CNC Feedrate Selection via Discrete Mechanistic and Geometric Model Integration
Authors: Hemmett Jeffrey G. , Fussell Barry K. , Jerard Robert B.
Published: March 2022

The purpose of this research is to determine the feasibility of automatically generating adaptive feedrates for five-axis CNC end milling. The complicated geometries involved with multiaxis machining make it difficult to manually estimate acceptable feedrates without being overly conservative. Our strategy is to use a computer simulation of the machining process to estimate the feeds based on in-process cutting information. The simulation consists of two distinct portions: a discrete geometric model of the material removal process, and a discrete mechanistic model of the cutting forces involved. The mechanistic model estimates cutting forces as a function of material properties of the stock and cutting tool, cut geometry, and feedrate. Used in an inverse manner, the mechanistic model can estimate the feedrates necessary to maintain a constant cutting force. This force may be selected to maintain a desired part tolerance, or to meet some other criteria (e.g. machine constraints). The cut geometry information required by the inverse mechanistic model is provided by the geometric model of the material removal process. The geometric model also dynamically stores in-process stock geometry as the simulation progresses. The results of this research has shown that it is possible to automatically generate adaptive feeds using these combined models.
Accurate Assessment of Flatness Tolerance Using Direct Search Optimization
Authors: Damodarasamy Sampath , Anand Sam
Published: March 2022

This paper presents a new method for determining the minimum zone for flatness of a point set obtained from a coordinate measuring machine. The two parallel planes that enclose the entire point set with minimum separation form the minimum zone for flatness. In this method, parallel planes are formed through each point in the point set for a range of plane orientations. Simplex search is used to determine the orientation of parallel planes that form the minimum zone. This method is applied to six example point sets and results are compared with other methods.
Thermal Performance Evaluation of VBGA Packages
Authors: Zheng Wen C. , Wu Paul Y. F. , Lan James J. D.
Published: March 2022

Photo-imageable-dielectric (PID) materials and the Micro-filled Via (MfVia) technology are utilized to make the ViperBGA (VBGA), a thermally enhanced BGA package substrate. The thermal performance of the VBGA packages was evaluated by wind tunnel tests of JEDEC standard and FEM simulations. It is shown that the thermal resistance Θja of any given package can be approximated by a rational function of the power level and the airflow speed. One advantage of such expression is that the thermal resistance of the package under any condition can be confidently predicted, and the other is that more reliable numerical predictions can be achieved. This paper also describes how to approach a confident FEM modeling of the wind tunnel tests in terms of heat transfer coefficients and other factors.
Two Test Specimens for Determining the Interfacial Fracture Toughness in Flip-Chip Assemblies
Authors: Yan Xiantao , Agarwal Rakesh K.
Published: March 2022

Two test specimens are developed to measure interfacial fracture toughness in flip-chip assemblies. The specimens consist three layers of silicon chip, underfill and circuit board. Two symmetric edge cracks are embedded along the interface either between the chip and the underfill or between the underfill and the circuit board. The specimens are subjected to four-point-bend loading and critical loads are obtained. Analytical solutions for energy release rate have been derived for these two specimens and used to obtain the toughness from the measured critical loads. These specimens have been used to evaluate material combinations of chip passivation, underfill and solder mask for desired interfacial strength.
Multi-Media Developments for a Laser Processing Curriculum
Authors: Kannatey-Asibu Elijah
Published: March 2022

Under the lasers in manufacturing curriculum development, a two-course sequence has been initiated into our curriculum. The courses, “Principles of Industrial Lasers,” and “Laser Materials Processing,” integrate theoretical and experimental research results in laser processing of materials with the fundamental characteristics of lasers. Each course constitutes three hours of lectures a week. Associated with each course is a required term project that involves modeling or analysis, computer simulation, and experimental implementation.
Towards Predictive Modeling and Optimization of Machining Operations
Authors: Jawahir I. S. , Balaji A. K. , Stevenson R. , van Luttervelt C. A.
Published: March 2022

The objective of this paper is to introduce an applied systems approach for prediction and optimization of machining performance. Current techniques for assessing machining performance are highly localized and traditionally biased towards the work material. An integrated systems approach is proposed for a reliable and consistent assessment of applied machining performance (AMP). Three areas, namely: fundamental modeling, applied modeling and optimization, are focused on. Fundamental modeling entails generic predictive models for machining performance measures (cutting forces/torque/power, tool-wear/tool-life, chip form/chip breakability, surface roughness/surface integrity, part accuracy, etc.). Applied modeling involves application of the generic models to a specific machining system, including the interactions of the three major elements: workpiece, machine tool and cutting tool. The subsequent step of optimization predicts the optimized machining performance (OMP).