bluuebunny/crossref_metadata_2025 huggingface dataset:
Obese Forklift Operator Neck Loads and Back Loads on a Sit Down Lift Truck During a Sudden Drop
Authors: Mkandawire Chimba , Imler Stacy , Smith James
Published: February 2017

Neck and back loads of sit down forklift operators have not been fully evaluated in the scientific literature. In this study, we evaluate the neck and back loads of an obese forklift operator who experiences a sudden vertical drop while operating a sit down lift truck. A ballasted 50th percentile male anthropomorphic test device (ATD) was used to measure loads available to a sit down forklift operator. Telemetry was used to remotely operate the sit down lift truck with the ATD properly belted. The belted ATD and lift truck were traveling, forks-leading along a stationary flatbed trailer when the right front forklift tire dropped into a defect in the floor. Several runs were performed at forklift travel speeds less than 5 miles per hour (2.2 meters per second). Back loads of the ATD were compared to activities of daily living (ADLs); and neck and back loads of the ATD were compared to published human tolerance levels and Injury Assessment Reference Values (IARVs) used in compliance testing. Review of ADLs, IARVs, and tolerance data show little correlation between the potential for spinal injury and experiencing a sudden drop while operating a sit down lift truck.
CPI Stress Induced Carrier Mobility Shift in Advanced Silicon Nodes
Authors: Sukharev Valeriy , Choy Jun-Ho , Kteyan Armen , Hovsepyan Henrik , Muehle Uwe , Zschech Ehrenfried , Radojcic Riko
Published: February 2017

Potential challenges with managing mechanical stress and the consequent effects on device performance for advanced 3D IC technologies are outlined. The growing need for a simulation-based design verification flow capable of analyzing and detecting across-die out-of-spec stress-induced variations in MOSFET/FinFET electrical characteristics is highlighted. A physics-based compact modeling methodology for multi-scale simulation of all contributing components of stress induced variability is described. A simulation flow that provides an interface between layout formats (GDS II, OASIS), and FEA-based package-scale tools, is also developed. This tool, can be used to optimize the floorplan for different circuits and packaging technologies, and/or for the final design signoff, for all stress induced phenomena. Finally, a calibration technique based on fitting to measured electrical characterization data is presented, along with correlation of the electrical characteristics to direct physical strain measurements.
Steel Sheets Impact Simulation for Safety Guards Design: Problems and Perspectives
Authors: Landi Luca , Amici Damiano
Published: February 2017

The growing need of design of safety guards for industrial workers led to the need for experimentation in the field of ballistics, typically used in the military research.

In the last few years some international standards for the safety of machine tools have been developed, such as the ISO 23125: 2010, improving the ballistic protection of safety guards. But it is still possible to find in the market a large quantity of machine tools with doubtful real protective characteristics of guards.

The uncontrolled projection of parts of work piece or tools can often cause very dangerous perforations of the safety guards. In such a way specific experimental tests like the ones conducted in EU, have assured the possibility to write appendices of ISO standards for safety guards design of machine tools.

These tests are based on impact between a particular standardized projectile, which exemplifies an impacting fragment of variable size and energy, and a flat plate placed in the trajectory of the projectile. The penetration or buckling of the target determines the non-suitability of a particular material of a given thickness, for the design and production of safety guards.

However these tests, have the following limitations: they are valid only for: a limited type of thickness and materials, a perpendicular impact with flat plates of about 500 mm × 500 mm and when the standardized penetrator is a cylinder with a prismatic head.

Moreover another limitation arises for the design of real safety guards: difficulties in taking into account curved design of guards such as the ones typically used in the spindles of machine tools. Moreover it is very difficult to take into account innovative materials different from the ones provided by the standards and also it is impossible to consider projected objects whose geometry is not regular, for example fragmented parts of tools, broken as a result of a wrong manoeuvre of the machine user.

The main focus of this paper is to test the applicability of numerical methods for the simulation of impacts on steel sheets of standardized penetrators for the numerical design and validation of industrial safety guards.

Correlation between experimental penetration tests found in international papers and optimized numerical tests will be presented.
Measurements and Visualization of the Flow in a Turbine Blade Tip Gap With Passive Jet Injection
Authors: Passmann Maximilian , Hasselmann Karsten , Bösche Harald , aus der Wiesche Stefan
Published: February 2017

Results of detailed measurements of the flow in a turbine blade tip are presented. The blades of the linear cascade were made by means of 3D-printing technology. Different clearances and the impact of a passive jet injection on the gap flow were investigated. The resulting velocity profiles in the gap were measured by means of a miniaturized Pitot-probe. To gain qualitative insights into the flow details, surface oil flow visualizations were performed. This classical method was extremely helpful for obtaining and interpreting occurring flow structures. The effect of an additional passive blade tip injection was investigated in detail and compared with the results obtained for plain blade tips without an additional injection. It was found that the overall flow structure was not greatly affected by the additional jet injection. But in case of moderate or large tip clearances, a local reduction of the tip leakage flow was achieved. The surface oil flow visualizations indicated a complex interaction of the jet with the gap flow. Such vortex interactions are well known in case of gas turbine film cooling technologies, but here rather similar observations were made in case of a confined flow configuration, too.
Evaluate the Importance of Shear Modulus in Dynamic FEM of Flexible Pavement Considering AC Cross-Anisotropy
Authors: Ahmed Mesbah U. , Tarefder Rafiqul A.
Published: February 2017

Goal of this study is to evaluate the effect of shear modulus variation on pavement responses, such as stress-strain, under dynamic load incorporating the AC cross-anisotropy. A dynamic Finite Element Model (FEM) of an instrumented asphalt pavement section on Interstate 40 (I-40) near Albuquerque, New Mexico, is developed in ABAQUS to determine stress-strain under truck tire pressure. Laboratory dynamic modulus tests were conducted on the AC cores to determine the temperature and frequency varying modulus values along both vertical and horizontal directions. The test outcomes are used to produce cross-anisotropic and viscoelastic parameters. Resilient modulus tests are conducted on granular aggregates from base and subbase layer to determine the nonlinear elastic and stress-dependent modulus values. These material parameters are integrated to the FEM through a FORTRAN subroutine via User Defined Material (UMAT) in the ABAQUS. The developed FEM is validated using the pavement deflections and stress-strain data under Falling Weight Deflectometer (FWD) test. The validated dynamic FEM is simulated under the non-uniform vertical tire contact stress. For the parametric study to investigate the effect of shear modulus variation on pavement responses, the validated FEM is simulated by varying the shear modulus in the AC layer. The results show that the variation in shear modulus along a vertical plane barely affects the tensile strain at the bottom of the AC layer and vertical compressive strains in both AC and unbound layers.
Time-Frequency Representation Based on Robust Local Mean Decomposition
Authors: Liu Zhiliang , Jin Yaqiang , Zuo Ming J.
Published: February 2017

Fourier transform based frequency representation makes an underlying assumption of stationarity and linearity for the target signal whose spectrum is to be computed, and thus it is unable to track time varying characteristics of non-stationary signals that also widely exist in the physical world. Time-frequency representation (TFR) is a technique to reveal useful information included in the signals, and thus the TFR methods are very attractive to the scientific and engineering world. Local mean decomposition (LMD) is a TFR technique used in many fields, e.g. machinery fault diagnosis. Similar to Hilbert-Huang transform, it is an alternative approach to demodulate amplitude-modulation (AM) and frequency-modulation (FM) signals into a set of components, each of which is the product of an instantaneous envelope signal and a pure FM signal. TFR can then be derived by the instantaneous envelope signal and the pure FM signal. However, LMD based TFR technique still has two limitations, i.e. the end effect and the mode mixing problems. Solutions for the two limitations greatly depend on three critical parameters of LMD that are boundary condition, envelope estimation, and sifting stopping criterion. Most reported studies aiming to improve performance of LMD have focused on only one parameter a time, and thus they ignore the fact that the three parameters are not independent to each other, and all of them are needed to address the end effect and the mode mixing problems in LMD. In this paper, a robust optimization approach is proposed to improve performance of LMD through an integrated framework of parameter selection in terms of boundary condition, envelope estimation, and sifting stopping criterion. The proposed optimization approach includes three components. First, the mirror extending method is employed to deal with the boundary condition problem. Second, moving average is used as the smooth algorithm for envelope estimation of local mean and local magnitude in LMD. The fixed subset size is the only parameter that usually needs to be predefined with a prior knowledge. In this step, a self-adaptive method based on the statistics theory is proposed to automatically determine a fixed subset size of moving average for accurate envelope estimation. Third, based on the first and the second steps, a soft sifting stopping criterion is proposed to enable LMD to achieve a self-adaptive stop for each sifting process. In this last step, we define an objective function that considers both global and local characteristics of a target signal. Based on the objective function, a heuristic mechanism is proposed to automatically determine the optimal number of sifting iterations in the sifting process. Finally, numerical simulation results show the effectiveness of the robust LMD in terms of mining time-frequency representation information.
Performance Evaluation of an Asymmetric Hybrid Solar Collector: Effect of Nanofluids on the Electrical and Thermal Energy Production
Authors: Nitsas M. T. , Koronaki I. P. , Kontos A. S.
Published: February 2017

The scope of this work is the analysis of the electrical and thermal performance of an asymmetric hybrid solar collector PVT and the prospect of the installation of a system consisting of these collectors in the Mediterranean region. For the purpose of this work, the Solarus V11 PVT collector (readily available in our laboratory) was chosen and numerically modeled. The main asset of this collector is its asymmetric reflector that consists of a circular and a parabolic part leading to a maximum thermal energy production even in winter as the solar radiation is concentrated in the edge of the reflector rather than in the center of it. Using a software developed in Matlab, the calculated data are presented for both thermal and electrical energy and they are compared with the hot water and electrical energy requirements (per month) around the Mediterranean territory. Furthermore, a parametric study is conducted in order to investigate the effect of the mass flow rate and the PVT array configuration on the thermal and electrical production, as well as the efficiency of the solar cells of the system. Moreover, in order to increase the PV cell efficiency, nanofluids, i.e. mixtures of nanometer size particles well-dispersed in a base fluid, are proposed as heat transfer fluids and the analysis for the performance evaluation is conducted for different nanoparticle loadings.
Analysis of an Adsorption Chiller Cooling System for Various Types of Solar Collectors Using the F-Chart Cooling Method
Authors: Koronaki I. P. , Papoutsis E. G. , Nitsas M. T.
Published: February 2017

Solar cooling systems offer a reliable and environmentally friendly alternative to conventional electrically driven vapor compression cooling units. Air conditioning systems powered by solar energy are very attractive because they have zero ozone depletion and global warming potential, their operational cost is low and they do not burden the electrical network during summer months.

In this study, the installation of a solar cooling system in various Greek cities is examined. The system utilizes a single-stage, two-bed silica gel-water adsorption chiller driven by heat produced by solar collectors. A lumped parameter model is used to simulate the performance of the adsorption chiller. The optimum tilt of the solar collectors is calculated for each examined city in order for the collected solar energy to be maximized during the summer period (April to September). The climatic data are taken from the technical notes of Greek Regulation for Buildings Energy Performance. Then, using the f-chart cooling method the necessary collectors’ surface area is estimated for every examined city and for different types of flat plate collectors (including advanced flat plate, simple flat plate and hybrid photovoltaic thermal collectors).
Highway Mounted Horizontal Axial Flow Turbines for Wind Energy Harvesting From Cruising Vehicles
Authors: Hegde Shreyas S. , Thamban Anand , Bhai Shah Palash Manish , Ahmed Arham , Upadhyay Meet , Joishy Ashish , Mahalingam Arun
Published: February 2017

Renewable energy technologies are a growing subject of concern these days. Wind energy is one among the renewable energy sources which has been implemented in a large scale for energy production. A large amount of capital has been invested in this field to harness energy and power homes. Wind energy from highways is usually unused and can provide a considerable amount of wind energy to drive a turbine due to high vehicle traffic and the speed of the vehicles. Extensive research on wind patterns is required to determine the average velocity of the wind created by oncoming vehicles. The objective of this work is to design and analyze a horizontal axis wind turbine to capture wind energy from moving vehicles on the highway. A computational fluid dynamics approach is used to solve this problem. The major innovation in this paper is that wind energy is being harvested in a very unique manner and also turbine power calculations have been done to quantify the amount of energy being harvested. Although a few of the literatures have discussed similar ideas power quantification has never been done. Also the entire mechanism has been simulated in MATLAB to find out the number of cars required to charge a battery which is very unique to this paper. Power calculations have been done for the turbine and validated against theoretical calculations which were done using the concept of velocity triangles. The idea is to have a separate mounting for cars and heavy vehicles which can be realized by having separate lanes on highways. The analysis will be done for vehicles moving in a range of speeds on the highway. The wind turbines will be placed on overhead shafts (the height of which is be determined suitably) thereby capturing the wind generated as a result of pressure difference. The mounts can also be used as signboards for vehicles moving on the highway and hence serve a dual purpose. In addition, extensive structural and fatigue analysis will be done for the turbines and the mounting structures in order to determine a suitable material for the turbine as well as the mounts to withstand the forces generated. Using all of the collected energy, existing amenities such as street lights on the medians can be powered by these wind turbines. Thus the main objective of this work is to complement the conventional electrical energy used for powering amenities along highways by a renewable source of energy (wind power) thereby leading to the concept of sustainable highways.
Phase-Doppler Anemometry Measurements in Water-Air Impinging Jet Flows
Authors: Xia Yakang , Khezzar Lyes , Alshehhi Mohamed
Published: February 2017

Flow visualization using high speed photography is used to study the structure of two liquid and one air impinging turbulent jets. The break up structure is discussed and the resulting spray angle at large air flow rates is obtained. The spray angle increases with the air flow rate except for the case when the water jet velocity is so small that the flow rate of air does not have significant effects on the spray angle. Phase Doppler Anemometry measurements of liquid droplet sizes and velocities are also given in terms of radial profiles at several axial locations from the point of impingement.
Environmental Effects on the Mechanical Properties of Small Structures
Authors: Allameh Seyed , Wardlow Jennifer
Published: February 2017

Size-effect is known to influence the mechanical properties of materials at micro- and nanoscales. Mechanisms of fracture and failure are often affected by environmental factors such as temperature and humidity. The latter is postulated to cause stress corrosion cracking in metallic and ceramic Microelectromechanical Systems (MEMS) components. A recently-developed hybrid microtester enclosed in an environmentally-controlled chamber was used to study the effects of temperature on the mechanical properties of small structures. MEMS-scale specimens, prepared from aluminum foam struts as well as covetic aluminum were tested in microtensile testing. Results of these micromechanical tests show that the tensile behavior of Al struts are similar at temperatures of 11 and 42 °C. Further, covetic Al samples show a higher strength at a lower temperature (15 °C), but higher ductility at a higher temperature (44 °C).
Effect of Reinforcement Fiber Length on the Mechanical Behavior of Biomimicked Composites
Authors: Allameh Seyed
Published: February 2017

Biomimicked composites have shown to be effective in reducing risk factors associated with the resistance of buildings against earthquakes. A significant amount of work is needed to determine what factors are critical in toughening composites used for homes, office buildings and other human dwellings. The effect of carbon fiber length on the mechanical properties of biomimicked composites was investigated. Composites made of cement, polymer and carbon fiber were fabricated in layers similar to the layering scheme of nacre and tested for toughness to determine the effects of fiber length. Preliminary results show an increase in the the strength of the composites with the fiber length. However, the effect is more pronounced on the increase in the fracture energy showing a linear relationship with the carbon fiber length.
Effect of Heat Treatment on Mechanical Properties of Laminated Carbon Fiber Reinforced Polymeric Composites
Authors: Islam A. B. M. I. , Kelkar Ajit D. , Zhang Lifeng
Published: February 2017

In recent years use of electrospun nanofibers and nanoparticles to improve the interlaminar properties have increased significantly. In most of the cases the additional interlaminar phase of nanofibers is required to go through various thermal and/or chemical processes. There has been emphasis to optimize the interlaminar nanofiber layers to achieve the optimum desired mechanical properties such as interlaminar strength. One common practice is to disperse nanofibers into the resin and then use the nanofiber enhanced resin to fabricate the laminated composites. However, proper dispersion and fiber filtering out are some of the problems that exist in fabrication using the nanofiber mixed resin approach. To alleviate this problem, an innovative approach of growing PAN (polyacrylnitrile) nano fibers directly on carbon fabric by electrospinning seems to solve the dispersion and fiber filtering problem. However, as PAN fibers require stabilization and carbonization, it is obvious that carbon fabric with PAN fiber deposition will have to undergo stabilization and carbonization process. The effect of stabilization and carbonization heat treatment on the mechanical properties of carbon fiber fabric is not yet fully understood. This paper presents the effects of heat treatment on carbon fabric used for fabricating laminated carbon fiber reinforced composite with epoxy resin. The heat treatment was performed at 280°C in air for six hours, and 1200°C for one hour in nitrogen which are similar to stabilization and carbonization of pure PAN fibers. The effects, due to heat treatment, were mainly characterized in terms of mechanical properties by performing tensile tests and shear tests. Fiber surface topography was observed by SEM to analyze physical changes. Chemical changes, corresponding to the existing groups with carbon fibers, were examined through FTIR. The results obtained are compared with a set of control laminated composite specimens, which were fabricated using heat vacuum assisted resin transfer molding (HVARTM) process and cured at 149°C. The two sets of composite were infused with resin in a single vacuum bag to ensure that both sets of specimens have identical resin infusion and cure cycle. Laminates used for making control specimens were fabricated using carbon fabric which did not undergo any heat treatment. A change in laminate thickness for heat treated carbon fabric was observed indicating a possible bulk up of the carbon fibers due to loss of sizing compounds, which also resulted into significant change in tensile properties.
Study of Efficiency Improvement and Optimization in CFB
Authors: Shastri Ajay Natraj
Published: February 2017

Circulating fluidized bed (CFB) boiler technology now-a-days is becoming dominant in the coal fired power generation across the globe; It is now biggest competitor to PC fired coal technology reason being fuel flexible, environment friendly, less water consumption along with cost benefits. Major Challenges such as efficiency improvement and adaptability to advance technologies such as SC, USC, and A-USC is becoming need of the future. World power generation industry going through tough challenge of abating carbon emission and greenhouse gases at the same time providing cheap, reliable and quality electricity. To cater this CFB being the popular choice, efficiency improvement in CFB has become mandatory. This paper aims to provide limelight on optimizing the efficiency aspects of CFB boiler, various fuels and fuel-mixes available through extensive study material. Paper will also address the boiler efficiency aspects as per ASME PTC 4.0. At the end of the discussion, paper concludes with recommendations for efficiency improvement in CFB boiler aims to be useful for researcher, clients, developer, and investors.
Calibration of a Design Tool for Dynamic Characteristics of Gas Labyrinth Seals
Authors: Kirk R. Gordon , Chen Wen Jeng
Published: February 2017

The analysis of all critical path high pressure machinery must include the account of the influence of the gas labyrinth seals. This paper reviews the prior work on labyrinth seal analysis starting in the 1980’s. The discussion gives a summary of the calibration of the bulk flow analysis to CFD results for a number of conditions. The calibration process was conducted over the last decade and the current paper presents the key results needed to justify the use of this bulk flow analysis for design of machinery with bladed labyrinth seals. A new design tool is discussed with illustrations of the type of seals that can be studied. The dynamic characteristics calculated using the labyrinth seal program can be used in rotordynamic analysis programs to predict the change in system stability produced by the gas labyrinth seals.
Interior Thermal Environment of a 6-Person Metal-Type Refuge Alternative (RA)
Authors: Yan Lincan , Yantek David , Klein Mark , Bissert Peter
Published: February 2017

In 2008, the Mine Safety and Health Administration (MSHA) published a final rule on Refuge Alternatives (RAs) for Underground Coal Mines [1]. The rule states that RAs should be “capable of sustaining trapped miners for 96 hours” and that RAs “can also be used to facilitate escape by sustaining trapped miners until they receive communications regarding escape options.” One of the main concerns with the use of RAs is heat and humidity buildup inside of them. The accumulation of heat and humidity could result in miners suffering heat stress or even death. MSHA regulations require that the apparent temperature in an occupied RA must not exceed 95°F. To investigate the thermal issues for occupied RAs, the National Institute for Occupational Safety and Health (NIOSH) conducted several tests on mobile RAs. In this paper, the test setup on a 6-person metal-type RA is described and the test results are presented. The test results show that the average measured air temperature within the RA increased by 9.0°C (16°F) and the relative humidity (RH) approached 91 %RH at the end of the 96-hour test. The test results were also compared to predictions from a thermal simulation model of the tested RA. The model predicted the average air temperature inside the RA at the end of 96 hours to within 0.4°C (0.8°F) of the average measured air temperature. Furthermore, two sets of test data with different heat inputs were used to cross-check the model validity.
A Super Singular Element for Three-Dimensional Corner Fronts
Authors: Ping Xuecheng , Chen Mengcheng , Zhu Wei
Published: February 2017

Three-dimensional (3-D) solids containing corner configurations with straight corner fronts are considered. A super polygonal prismatic element containing a straight corner front is established by using the numerical eigen-solutions of singular stress fields and Hellinger-Reissner variational principle. Singular stresses near corner fronts for far-field boundary conditions can be obtained by incorporating the super singular element with the conventional three-dimensional (3-D) brick elements. The numerical studies are conducted to demonstrate the simplicity of the proposed technique in handling fracture problems of 3-D through-thickness cracks. The usage of the super singular element can avoid mesh refinement near the corner front domain, and the simulation results have high accuracy and fast convergence speed. Compared with the conventional finite element methods and existing analytical methods, the present method is more suitable for dealing with complicated problems of stress singularity in elasticity including multiple defects.
Comparing Computational and Experimental Failure of Composites Using XFEM
Authors: Hulton Andrew W. , Cavallaro Paul V.
Published: February 2017

Fiber reinforced polymer (FRP) composites have been used as a substitute for more conventional materials in a wide range of applications, including in the aerospace, defense, and auto industries. Due to the widespread availability of measurement techniques, experimental testing of composite materials has outpaced the computational modeling ability of such complicated materials. With advancements in computational physics-based modeling (PBM) such as the finite element method (FEM), strides can be made to reduce the efforts required in building and testing future composite structures. In this work, the extended finite element method (XFEM) is implemented to model fracture of composite materials under quasistatic loading. XFEM is applied to a three-dimensional (3D) computational model of a carbon fiber/epoxy composite cylinder, in half symmetry, that is subjected to lateral compression between two flat plates. Independent material properties are instituted for each composite layer, depending on individual layer orientation. The crack path produced by the analytical results is compared to experimental testing of lateral compression of a composite cylinder. Fracture site initiation and growth path are consistent in both the experimental and computational results.
A Study on Structural Safety Evaluation Technology for Pressing Rings in a Transformer
Authors: Yun Minok , Lee Jinwoo , Kim YeongCheol
Published: February 2017

In transformers, pressing rings are used to maintain clamping force on the windings. Recently, the importance of structural safety evaluation on pressing ring design has been growing due to reaction forces from the windings. In this paper, a set of data from mechanical tests is presented. The tests were conducted on insulation materials. Additionally, equations were derived in order to calculate stress and deflection of pressing rings. As a result, the proposed equations of pressing rings were applied in the actual product design. Then, analysis based on numerical method and deflection measurements of real pressing rings were conducted to verify the proposed equations. Through this process, the evaluation technology suggested in this paper was validated.
Transient Multiphase Simulation in Separator Vessel Internals Design in Saudi Aramco
Authors: Al-Khalifa Hussain A. , Oshinowo Lanre , A. Al-Saif Omar
Published: February 2017

The design of new multiphase separation plants or the replacement of vessels represents an opportunity to review and update the separation systems, to ensure the surface facilities lifetime with maturing production conditions. Potentially adverse operating scenarios involving slug flow could occur in the production header, leading to potentially damaging fluid forces acting on the high-pressure production trap internals. The internals design is based on the fluid forces occurring during a slug flow condition.

This paper presents the application of 3-D Computational Fluid Dynamics (CFD) to simulate the realistic fluid forces acting on a novel separator inlet device, and to assess the structural integrity of the mechanical design. To generate slug conditions resulting from several adverse, but low probability, operating scenarios, OLGA, a 1-D transient multiphase flow hydraulic simulation application, was used to simulate the transient multiphase flow conditions in the production header entering the production separator using the 20-year production forecast. In a one-way coupling, the output from OLGA is used as input to the CFD model. The scenarios were carefully developed, thoroughly evaluated and agreed on by the different project stakeholders — technical services, operations and project management teams.

The OLGA simulations produced the transient phase velocities and hold-ups that were applied as inlet boundary conditions to the CFD models of the separator. The transient CFD turbulent multiphase simulations used the Volume-of-Fluid model to track the gas-oil-water mixture in the inlet device and the inlet section of the separator. A discussion on the appropriate CFD multiphase model selection is presented. The hydrodynamic forces computed in the CFD model are integrated over the internal surfaces of the inlet device and mapped as a distributed pressure load for a Finite Element Analysis (FEA) structural model, to determine the mechanical reactions of the structure, a fluid-structure interaction (FSI) analysis. The methodology developed is intended for use in new internal designs for two- and three-phase separators, and slug catchers in gas/oil separation plants (GOSPs).
Strength Analysis of AL-7F-1 Engine Turbine Rotor Blade
Authors: Klimko Marek , Mrozek Lukas , Noga Tomas , Linhart Jiri
Published: February 2017

The key intent of the article is to describe clearly the strength issue of blades for aircraft engines, on the basis of which to create a calculation algorithm and apply it to a particular blade. The work then deals with a strength analysis of a rotor blade used in the gas turbine of an AL-7F-1 turbocharger aircraft engine. The article describes comprehensively in terms of strength the influences which act on the blade during operation. Generally, these loads can be divided into static load, which includes the tensile stress generated by the rotating mass of the blades, bending and torsion moments caused by the kinetic energy of the flowing gas. The last part of the article is dedicated to the issue of compensation of the bending moments acting on the turbine blades, resulting in analytical calculation of the blade inclination angles in the critical cross section.
The Orbitless Drive
Authors: Stocco Leo
Published: February 2017

A fixed low-ratio Epicyclic drive is developed that resembles a Planetary drive but has crank-shaft pinions and an additional carrier replacing its ring gear. It provides half the reduction ratio of a Planetary drive with similar pinions, making reduction ratios at or near 2:1 practical. It shares many properties with a Planetary drive such as torque splitting and co-axial drive shafts that spin in a common direction but with no ring gear, reverse bending, or assembly criteria. It has many optional configurations and modes, does not slip or jam, is easily back-driven, has low pitch and bearing velocities, and favorable churning properties. It is a viable option for both reduction and overdrive applications that promises low noise / vibration / harshness (NVH) levels.
A Convenient Low Order Thermal Model for Heat Transfer Characteristics of Single Floored Low-Rise Residential Buildings
Authors: Anand Nadish , Gould Richard D.
Published: February 2017

A low order thermal model is introduced to determine the thermal characteristics of a Low-Rise Residential (LRR) building and then predict the energy usage by its Heating Ventilation & Air Conditioning (HVAC) system according to future weather conditions. The LRR buildings are treated as a simple lump and the model is derived using the lumped capacitance model for transient heat transfer from bodies. Most contemporary HVAC systems have a thermostat control, which has an offset temperature, and user defined set point temperatures, which defines when the HVAC system will switch on and off. The aim is to predict, with minimal error, the inside air temperature, which is used to determine the switching on and off, of the HVAC system. To validate this lumped capacitance model we have used the EnergyPlus simulation engine, which simulates the thermal behavior of buildings with considerable accuracy. We have predicted using the low order model the inside air temperature of a single family house located in three different climate zones (Detroit, Raleigh & Austin) and different orientations for summer and winter seasons. The prediction error between the model and EnergyPlus is less than 10% for almost all the cases with the exception of Austin in summer. Possible factors responsible for error in prediction are also noted in this work, paving way for future research.
On the Flame-Flow Interaction Under Distributed Combustion Conditions
Authors: Khalil Ahmed E. E. , Gupta Ashwani K.
Published: February 2017

Colorless Distributed Combustion (CDC) has shown significant improvements in terms of high combustion efficiency, ultra-low pollutants emission, low combustion noise, uniform thermal field, and enhanced stability. Colorless distributed combustion is fostered through reduced oxygen concentration and high temperature oxidizer to result in distributed reaction over a larger volume of the combustor and uniform thermal field. In this paper, the interaction between fluid mechanics (velocity field, characterized through particle image velocimetry) and the reaction region (identified through hydroxyl planar laser induced fluorescence) is investigated with focus on swirl assisted distributed combustion. Nitrogen/Carbon Dioxide mixture was added to the normal air upstream of the burner to simulate the hot reactive gases. Comparing the PIV data for reacting conditions with OH-PLIF revealed significant difference between normal swirl and CDC flames. In swirl flame, the flame was located around the shear layer of the entry jet (with both the inner and outer recirculation zones) where the velocity fluctuations and OH-PLIF fluctuations coincided. Flame transitioning to CDC pushed the reaction zone further downstream to locate at a position of lower velocity than what was found for swirl flames. In addition, the reaction zone occupied a much larger volume with lower signal intensity to exhibit distributed reaction. Experiments performed at same flow rates and velocities but with no reduction in oxygen concentration confirmed that the change in reaction behavior is attributed to the lower oxygen concentration rather than the increased flowrates due to dilution.
Numerical Investigation on Slot Casing Treatment in a Transonic Axial Compressor Stage: Part 2 — Unsteady Simulations and Analysis
Authors: Zhu Mingmin , Qiang Xiaoqing , Teng Jinfang
Published: February 2017

Slot-type casing treatment generally has a great potential of enhancing the operating range for tip-critical compressor rotors, however, with remarkable efficiency drop. In the first part of this two-part words, several configurations of slot casing treatment were tested in a 1.5 transonic compressor stage by steady simulations. One kind of arc-curve skewed slot contributed to considerable stall margin improvement with minimum efficiency loss. However, interaction between main passage and casing treatment was inherently unsteady. Steady simulation was inadequate to provide accurate compressor performance prediction and precise flow field details. Thus, this part was aimed at clarifying the differences between steady and unsteady simulations. The unsteady interaction process between main passage flow and slots were also detailed interpreted. Unsteady simulation was conducted by applying sliding interface between rotor passage and arc-curved skewed slots. Firstly, differences of compressor performance were examined between steady and unsteady methods. Results showed that steady simulation underestimated stall margin improvement and efficiency drop by casing treatment. Then analysis on aerodynamic parameters and specific flow fields were carried out at smooth casing peak efficiency and casing treatment near stall conditions. Unsteady simulation provided more than 50% larger mass flow rate entering or exiting slots opening surfaces at both operating conditions. It revealed that in unsteady simulation, casing treatment contributed to stronger suction/injection process, which promoted tip flow fields more effectively than steady simulation. Axial velocity deficit at rotor outlet was refilled by slots more effectively in unsteady simulation. In steady result, a large low momentum blockage existed inside rotor passage near tip region and prevented flow from entering the passage at near stall condition. While in unsteady simulation at the same condition, incoming flow was still able to travel across rotor passage in a high velocity. Further, instantaneous flow fields near tip region and inside the slots were particularly examined during a rotor blade passing period to elaborate the unsteady flow interaction. The mid-pitch surface of a representative slot was selected to represent the re-circulation procedure inside slots. Unsteady flow fields and spectrum analysis manifested that tip flow field was dominated by slots passing, while re-circulation process inside slots was dominated by blade passing. Low pressure region inside the blade passage facilitated the injection process. Circulation inside slots lagged behind the pressure variations beneath slots. When the slot was striding over the blade tip, intense injection didn’t emerge immediately beneath slots’ front portion. Until the high pressure region moved away from the slot opening surface, fluids inside the slots started to inject into the main flow in high speed.
Comparative Thermal Performance of a Parabolic Trough Receiver With Cu-Therminol®VP-1, Ag-Therminol®VP-1 and Al2O3-Therminol®VP-1 Nanofluids
Authors: Mwesigye Aggrey , Huan Zhongjie , Meyer Josua P.
Published: February 2017

As parabolic trough systems with high concentration ratios become feasible, convective heat transfer enhancement is expected to play a significant role in improving the thermal and thermodynamic performance of these systems. In this paper, the thermal performances of a high concentration ratio system using three different types of nanofluids were investigated. A system with a geometric concentration ratio of 113 and a rim angle of 80° was used in this study. The nanofluids considered were copper-Therminol®VP-1, silver-Therminol®VP-1 and Al2O3-Therminol®VP-1 nanofluid. For each nanofluid, the volume fraction of the nanoparticles in the base fluid was varied from 0–6%. The numerical solution was obtained using a finite volume based computational fluid dynamics tool. Temperature dependent properties were used for both the base fluid and the nanoparticles. An actual receiver heat flux boundary condition obtained using Monte Carlo ray tracing was coupled to the computational fluid dynamics code to model the thermal performance of the receiver. Results show that for each nanofluid used, the thermal performance of the receiver improves significantly. The thermal efficiency increases by about 12.5%, 13.9% and 7.2% for the copper-Therminol®VP-1, silver-Therminol®VP-1 and Al2O3-Therminol®VP-1 nanofluids, respectively as the volume fraction increases from 0 to 6%. The thermal efficiency improvement with silver-Therminol®VP-1 was the highest of the considered nanofluids owing to the relatively higher thermal conductivity of silver.
Novel Direct Model for Machining Regenerative Chatter
Authors: Lalley Aaron , Bedillion Mark
Published: February 2017

Regenerative machining chatter or resonance in the machining process has traditionally been modeled with the stability lobe approach. This paper presents a new time based direct simulation model and compares it with traditional stability lobe modeling. The direct model has the ability to discriminate directional and time information, resulting in a number of advantages over frequency-based stability lobe analysis.
The Reliability of a Component Under Multiple Cyclic Stress Levels With Distributed Cyclic Numbers
Authors: Le Xiaobin
Published: February 2017

Fatigue damage is initiated through some “defects” on the surfaces of and/or inside the component and induced by the fatigue cyclic loadings. These “defects” are randomly scattered in components, and one of these “defects” will be randomly “activated” and finally developed to become the initial crack which causes the final fatigue failure. Therefore, the fatigue strength is inherently a random variable and should be treated by probabilistic models such as typical P-S-N curves. The fatigue cyclic loading could be presented or described in any form. But the fatigue loading spectrum can generally be grouped as and described by these five models: (1) a single constant cyclic stress (loading) with a given cyclic number, (2) a single constant cyclic stress with a distributed cyclic number, (3) a distributed cyclic stress (loading) at a given fatigue life (cyclic number), (4) multiple constant cyclic stress levels with given cyclic numbers, and (5) multiple constant cyclic stress levels with distributed cyclic numbers. The approaches for determining the reliability of components under fatigue loading spectrum of the models 1∼4 are available in literature and books. But few articles and books have addressed an approach for determining the reliability of components under the fatigue loading spectrum of the model 5. This paper will propose two approaches for addressing this unsolved issue. Two examples will be presented to implement the proposed approaches with detailed procedures.
Finite Element Analysis of an Electro-Mechanical Knee Loading Device
Authors: Prabhala Sai Krishna , Anwar Sohel , Yokota Hiroki , Chien Stanley
Published: February 2017

The mechanical loading of knee is an effective regimen for treatment of bone related ailments like fractures, osteoarthritis, and osteoporosis [1–2]. Efficacy of knee loading is evident from the previous studies done on rodents and other small animals [3]. In order to test this loading concept on human subjects, a prototype of a portable and compact device was designed previously. In this study, the prototype device was re-designed with a modified slider crank mechanism. Since this device has multiple moving parts, durability of the parts under stress is a key factor for its success. Thus, this paper focuses on its mechanical characteristics using finite element analysis (FEA). In particular, structural deformities and modal frequency characteristics are analyzed. The FEA analysis is performed on a CAD model of the device. The static structural and modal analyses are performed on two different configurations, in which different materials were used for selected components. Individual parts were meshed and solved extensively to obtain useful results under maximum loading conditions, such as total deformation, Von Mises stress, and modal frequencies. The analysis results show that ABS plastic based design provides an optimal solution in terms weight, cost, and usability.
Process Simulation and Energy Analysis of Oxy-Coal Combustion Steam Systems (OCCSS) With Near-Zero Emissions Based on Coal Gasification
Authors: Wang Pengxiang , Zhao Yijun , Sun Shaozeng
Published: February 2017

Oxy-coal combustion steam system with near-zero emissions (OCCSS) is a new type of power generation system, which is able to satisfy the demands for high efficiency utilization of coal and control of CO2 emissions. It is necessary to study the characteristics of the new system, since both the combustion mode and the working medium are different to the power systems utilizing conventional combustion. In the present paper, we report the process simulation of a conceptual OCCSS based on coal gasification, as well as comparisons with a conventional combustion and an oxy-fuel combustion. The model of the system was built and parametric studies showed the pressure of burners and ratios of fuel have effects on the performance of the system. The net efficiency of power generation increases quickly with the increasing pressure of the gas generator followed by a slower decrease. The net efficiency of the system increases with the increasing fuel ratio to a burner which is set before any burners with decreasing ratio. Otherwise, it decreases. The energy analysis shows the net efficiency of OCCSS is higher than the conventional combustion system and the oxy-fuel combustion system.