bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study of Aerodynamic Noise From a Double Shaft Fan
Authors: Madadnia Jafar , Alshehri Faisal , Tilwa Kaushik 
Published: July 2013

Noise pollution from wind turbines and blowers operating in the vicinity of residential buildings has in recent years been the focus of intensive research. This paper reports on the outcome of an experimental investigation to reduce the noise pollution through design, build and testing of a counter-rotating-double-row-fan with variable spacing. A single-row fan was selected as the benchmark fan. The mechanical noise and the background ambient noise were measured using the system operating with no-blades. The aerodynamic noise from the fan was then focused and air velocity, shaft-revolution, input-electric-power to fan, amplitude (dB) and Center Frequency (CF) in Hz of noise were measured using frequency-weighting of both “A” and “Linear”. Coefficients of performance (COP), dB, CF, Tip speed ratio (TSR) were plotted for a range of spacing between two-blade-rows.
It was noticed that double-shaft-fan relative to the benchmark single shaft fan has operated:
a) At a lower TSR due to division of the motor power between two shafts.
b) At a higher COP of up to 18% due to a higher air velocity generated at the same motor power.
c) Quieter at a lower dB (of up to 10 dB).
d) At the minimum noise levels (80 dB) at the spacing of 15mm-to-25mm, using the “Lin”-weighting.
e) At the minimum noise levels (20 dB) at the spacing of 12mm-to 50 mm when measured at the “A”-weighting.
f) With no significant change in frequency of noise when operate at the same TSR.
Solar-Powered Reformed Methanol Fuel Cell System
Authors: Hotz Nico 
Published: July 2013

The present study investigates the feasibility, efficiency, and system design of a hybrid solar fuel cell system generating electric power for stationary applications such as residential buildings. The system is fed by methanol and combines methanol steam reforming and Proton Exchange Membrane (PEM) fuel cells with solar collectors to generate the required heat for the steam reforming.
The synergies of these technologies lead to a highly efficient system with significantly larger power densities compared to conventional systems and generate tremendous advantages in terms of installation and operation costs. The present investigation describes the entire proposed system and its components and presents first analytical, numerical, and experimental results of a larger project to prove the feasibility of such a system by analyzing first a bench test demonstrator generating around 10 W of electric power and finally a prototype for an entire single-family household. It is shown that the methanol-to-electricity efficiency of the entire system is above 50%.
The Technical Derivation of Heat Transfer Performance of the Airside of a Novel Pin Design Heat Exchanger Using Computational Fluid Dynamics
Authors: Churitter Tosha 
Published: July 2013

Pins are a common type of extended surface used in the field of heat transfer; their main application being in the electronics field. Historically, pins used in heat exchangers have diameters that are considered negligible in comparison to their lengths and are therefore termed as tubes.
In this report, the use of pins as an extended surface is investigated for the heat transfer on the airside (cold) of the Compact Advanced Pin Surface Heat Exchanger. The pins are circular in cross section and follow a staggered arrangement. The uniqueness of the pin design is such that they cannot be treated as tubes.
Key Pin Design features are as follows:
• Pins have a maximum Length: Diameter ratio of 3.
• Pin Spacing to Pin Diameter ratio is greater than in traditional arrangements.
• Pins function as a primary as well as secondary surface.
The heat transfer performance of extended surfaces possessing the above features has not been characterized, using commercially available Computational Fluid Dynamics (CFD) software, in any research specifically focused on applications for the aerospace industry.
Based on actual test results, this study specially develops a unique approach that can predict the outlet temperature of the heat exchanger to within 1% accuracy. This ‘developed’ approach is applied over cold-side mass flow rates ranging from 0.05 kg/s to 0.23 kg/s, while keeping the hot side mass flow rate constant at 0.05 kg/s. At worst, the simulation results lie within 5% accuracy and at best the simulation accuracy is 1%, a significant improvement on traditional derivations.
This article specifically discusses the methodology developed to analyse the heat transfer performance of the novel pin design using Fluent 6.2. It highlights the current limitations of existing equations as well as the theoretical knowledge gap that currently exists in the analysis of pins as extended heat transfer surfaces in heat exchangers.
Mathematical Modeling of Heat and Mass Transfer Processes During Pyrolysis and Combustion of a Single Biomass Particle
Authors: Haseli Y. , van Oijen J. A. , de Goey L. P. H. 
Published: July 2013

A detailed mathematical model is developed for simulation of heat and mass transfer processes during the pyrolysis and combustion of a single biomass particle. The kinetic scheme of Shafizadeh and Chin is employed to describe the pyrolysis process. The light gases formed during the biomass pyrolysis is assumed to consist of methane, carbon dioxide, carbon monoxide, hydrogen and water vapor with given mass fractions relevant to those found in the experiments of high heating conditions. The combustion model takes into account the reactions of oxygen with methane, hydrogen, carbon monoxide, tar and char as well as gasification of char with water vapor and carbon dioxide. Appropriate correlations taken from past studies are used for computation of the rate of these reactions.
The model allows calculation of time and space evolution of various parameters including biomass and char densities, gaseous species and temperature. Different experimental data reported in the literature are employed to validate the pyrolysis and combustion models. The reasonable agreement obtained between the predictions and measured data reveals that the presented model is capable of successfully capturing various experiments of wood particle undergoing a pyrolysis or combustion process. In particular, the role of gas phase reactions within and adjacent to particle on the combustion process is examined. The results indicate that for the case of small particles in the order of millimeter size and less, one may neglect any effects of gas phase reactions. However, for larger particles, a combustion model may need to include hydrogen oxidation and even carbon monoxide combustion reactions.
Thermal Modeling for High Thermal Conductivity Thermal Ground Planes
Authors: Ababneh Mohammed T. , Chamarthy Pramod , Chauhan Shakti , Gerner Frank M. , de Bock Peter , Deng Tao 
Published: July 2013

Thermal ground planes (TGPs) are flat, thin (external thickness of 2 mm) heat pipes which utilize two-phase cooling. The goal is to utilize TGPs as thermal spreaders in a variety of microelectronic cooling applications. TGPs are novel high-performance, integrated systems able to operate at a high power density with a reduced weight and temperature gradient. In addition to being able to dissipate large amounts of heat, they have very high effective axial thermal conductivities and (because of nano-porous wicks) can operate in high adverse gravitational fields.
A three-dimensional (3D) finite element model is used to predict the thermal performance of the TGP. The 3D thermal model predicts the temperature field in the TGP, the effective axial thermal conductivity, and the evaporation and the condensation rates. A key feature of this model is that it relies on empirical interfacial heat transfer coefficient data to very accurately model the interfacial energy balance at the vapor-liquid saturated wick interface. Wick samples for a TGP are tested in an experimental setup to measure the interfacial heat transfer coefficient. Then the experimental heat transfer coefficient data are used for the interfacial energy balance. Another key feature of this model is that it demonstrates that for the Jakob numbers of interest, the thermal and flow fields can be decoupled except at the vapor-liquid saturated wick interface. This model can be used to predict the performance of a TGP for different geometries and implementation structures. This paper will describe the model and how it incorporates empirical interfacial heat transfer coefficient data. It will then show theoretical predictions for the thermal performance of TGP’s, and compare with experimental results.
Development of a Three-Dimensional Iterative Methodology Using a Commercial CFD Code for Flow Scouring Around Bridge Piers
Authors: Elapolu Phani Ganesh , Majumdar Pradip , Lottes Steven A. , Kostic Milivoje 
Published: July 2013

One of the major concerns affecting the safety of bridges with foundation supports in river-beds is the scouring of river-bed material from bridge supports during floods. Scour is the engineering term for the erosion caused by water around bridge elements such as piers, monopiles, or abutments. Scour holes around a monopile can jeopardize the stability of the whole structure and will require deeper piling or local armoring of the river-bed. About 500,000 bridges in the National Bridge Registry are over waterways. Many of these are considered as vulnerable to scour, about five percent are classified as scour critical, and over the last 30 years bridge failures caused by foundation scour have averaged about one every two weeks. Therefore it is of great importance to predict the correct scour development for a given bridge and flood conditions. Apart from saving time and money, integrity of bridges are important in ensuring public safety. Recent advances in computing boundary motion in combination with mesh morphing to maintain mesh quality in computational fluid dynamic analysis can be applied to predict the scour hole development, analyze the local scour phenomenon, and predict the scour hole shape and size around a pier.
The main objective of the present study was to develop and implement a three dimensional iterative procedure to predict the scour hole formation around a cylindrical pier using the mesh morphing capabilities in the STARCCM+ commercial CFD code. A computational methodology has been developed using Python and Java Macros and implemented using a Bash script on a LINUX high performance computer cluster. An implicit unsteady approach was used to obtain the bed shear stresses. The mesh was iteratively deformed towards the equilibrium scour position based on the excess shear stress above the critical shear stress (supercritical shear stress). The model solves the flow field using Reynolds Averaged Navier-Stokes (RANS) equations, and the standard k–ε turbulence model. The iterative process involves stretching (morphing) a meshed domain after every time step, away from the bottom where scouring flow parameters are supercritical, and remeshing the relevant computational domain after a certain number of time steps when the morphed mesh compromises the stability of further simulation. The simulation model was validated by comparing results with limited experimental data available in the literature.
The Influence of Thermal Barrier Coating Surface Roughness on Spark-Ignition Engine Performance and Emissions
Authors: Memme Silvio , Wallace James S. 
Published: July 2013

The separate effects on heat transfer of 1) piston crown surface finish and 2) the use of a metal based thermal barrier coating (MTBC) on the piston crown of a spark ignition (SI) engine were quantified through experimental analysis in a single cylinder CFR engine. Measured engine parameters such as power, fuel consumption, emissions and cylinder pressure were used to identify the effects of the coating and its surface finish. Two piston coatings were tested: a baseline copper coating and a metal-based thermal barrier coating. Each coating was tested at multiple surface finishes. Tests showed that reducing surface roughness of both coatings increased in-cylinder temperature and pressure as a result of reduced heat transfer through the piston crown. For both coatings, this resulted in small improvements (∼3%) in power and fuel consumption, while also having a measurable effect on emissions. Oxides of nitrogen emissions increased while total hydrocarbon emissions generally decreased as a result of polishing. The polished coatings were also seen to increase in-cylinder peak pressures and burn rates.
Improvements attributed to the TBC were found to be small, but statistically significant. At an equivalent surface finish, the MTBC-coated piston produced slightly higher power output and peak pressures. Hydrocarbon emissions were also seen to be significantly higher for the MTBC-coated piston due to its porosity. The effectiveness of the coating was found to be highly dependent on surface finish.
Integrated Physical and Chemical Measurements of PM Emissions of Dispersing Plume Heavy-Duty Diesel Truck: Wind Tunnel Studies: Part I — Design and Commissioning
Authors: Littera D. , Velardi M. , Cozzolini A. , Yoder G. , Besch M. C. , Carder D. K. , Gautam M. 
Published: July 2013

Over the past few decades there has been considerable progress made in understanding the processes leading to formation and evolution of particulate matter (PM) emissions from heavy duty diesel engines (HDDE). This progress has been primarily made under controlled laboratory conditions with the use of constant volume sampling (CVS) systems and to a limited extend through on-road chase studies. West Virginia University (WVU) is attempting to close the present knowledge gap by conducting detailed experiments in a custom designed and constructed environmental wind tunnel. The understanding and knowledge has recently been further extended to new emission reduction technologies, such as the diesel particulate filter (DPF) which has dramatically changed the size distribution and chemical composition of PM. Additionally, the selective catalytic reduction (SCR) technology has shown to further enhance the formation of nucleation mode particles as well as alter their morphology. Even with advances in technology there remains a considerable gap in the current level of understanding of PM formation and evolution, since the combustion generated PM from diesel engines is not discernible from the atmospheric background PM measured beyond 300m from highways. After being emitted from the vehicle exhaust system, the process of dilution in the atmosphere leads to a multitude of PM transformation phenomena, such as volatilization, coagulation, and condensation. The work presented herein has been divided into two parts which are published separately from each another.
The first part describes the design and commissioning process of the wind tunnel focusing on both, aerodynamic and structural constraints, which ultimately led to the definition of the main characteristics of the facility. The resulting design is a subsonic, non-recirculating, suction type tunnel, with a 16ft high and 16ft wide test section capable of housing a full-size heavy-duty tractor cab. A 2,200hp suction fan is employed to provide up to 80 mph wind speeds. The 115ft test cell length guarantees for a 2 second residence time for the exhaust plume evolution (at 35 mph) and complies with turbulence intensity (less than 1%) and quality flow requirement as identified for this type of application. In addition, the West Virginia University (WVU) wind tunnel has been equipped with a custom made sampling system able to move in all three dimensions in order to measure spatially resolved plume characteristics.
The second part will describe the actual test procedures and the experimental results and will be published in a separate paper.
Modeling of Ignition and Combustion for Glow Plug Assisted Direct Injection Natural Gas Engines
Authors: Cheng Stewart Xu , Wallace James S. 
Published: July 2013

Direct injection natural gas (DING) engines offer the advantages of high thermal efficiency and high power output compared to spark ignition natural gas engines. Injected natural gas requires some form of ignition assist in order to ignite in the time available in a diesel engine combustion chamber. A glow plug — a heated surface — is one form of ignition assist.
Simple experiments show that the thickness of the heat penetration layer of a glow plug is very small (≈10−5 m) within the time scale of the ignition preparation period (1–2 ms). Meanwhile, the theoretical analyses reveal that only a very thin layer of the surrounding gases (in micrometer scale) can be heated to high temperature to achieve spontaneous ignition. A discretized glow plug model and virtual gas sub-layer model have been developed for CFD modeling of glow plug ignition and combustion for DING diesel engines.
In this paper, CFD modeling results are presented. The results were obtained using a KIVA3 code modified to include the above mentioned new developed models. Natural gas ignition over a bare glow plug was simulated. The results were validated against experiments. Simulation of natural gas ignition over a shielded glow plug was also carried out and the results illustrate the necessity of using a shield.
This paper shows the success of the discretized glow plug model working together with the virtual gas sub-layer model for modeling glow plug assisted natural gas direct injection engines. The modeling can aid in the design of injection and ignition systems for glow plug assisted DING engines.
Lubrication Film Thickness Behavior Under Transient Speed and Load Conditions
Authors: Zimmerman Martin , Krupka Ivan , Hartl Martin , Houska Pavel 
Published: July 2013

In engineering practice no machine parts are working under ideal steady-state conditions. The transient conditions involved in particular cases of real machine assemblies like cam follower contacts, ball bearings etc. represent a really complex sequence of movements. In these applications high sliding conditions are often replaced by zero entrainment speed connected with squeezing action and followed by opposite sliding. In general the variation in speed of contact surfaces strongly affects the film thickness and it can result in a lubricant film breakdown and in consequence also damage of contact surfaces. Experimental study will also consider the effect of surface topography and dynamic change of load.
A new concept of experimental apparatus was used for experimental study of cam and tappet contact under simplified operational conditions. To simplify the problem the concept of cam and tappet contact was replaced by EHD contact of the flat surface of chromium coated glass disk and a steel ball. Also only transient speed and load were taken into account. The method used to measure film thickness was thin film colorimetric interferometry. A high-speed digital camera was used in combination with a high power xenon lamp to capture rapid changes of film thickness in the contact area. Servomotors and piezo-actuator were used to control the speed of contact surfaces and also the load of the contact during the experiment.
The experimental results show that the change of speed has a great impact on film behavior during sequences where opposite sliding or zero entrainment speed is involved. It was found that shallow grooves can behave as a reservoir of lubricant which can supply the contact area and increase the film thickness during the above described transient phenomena.
Analysis of Primary Standards for Pipeline Operation Safety and Security in China
Authors: Zheng Juan , Zhao Jinyun , Shui Biyuan , Wu Kaixuan , Zhang Lili 
Published: July 2013

Over 40,000 kilometers of pipeline transporting natural gas, oil, and other hazardous liquids have been built from 2001 to 2010 in China. More than 100,000 kilometers pipeline will be constructed from 2011 to 2015. While being considered as an efficient and safe means, many pipelines carry materials with the risk to cause public injury and environmental damage. Pipeline safety and security issues involve with many groups: the government, oil and gas pipeline companies, and local communities. Standards play an important role to ensure these groups working together to achieve common goals. Pipeline operation safety and security mainly rely on the partial or complete incorporation of standards by reference. Standards Development Organizations (SDO) and pipeline companies have done lots of work to make the standards working well in the past ten years. The “standard analysis project” was one of them that were taken to improve pipeline safety and security.
This paper briefly reviews the primary standards which consist of national standards, industry standards and enterprise standards for pipeline operation safety and security. Combined with the technical development and the pipeline operation situation, the standards were analyzed, especially for the differences of technical specifications in the standards. Several aspects are pointed out as the key issues to improve pipeline operation safety and security standards, including pipeline integrity management standards, pipeline Safety Instrumented System standards, standards preventing pipeline from Third Party Damages, standards protecting environment from unexpected oil pollution, and permafrost areas pipeline operation and maintenance standards. In addition to the issues mentioned above, the related legislation situation in China is also taken into consideration. Keeping and improving pipeline safety and security is a task that not only needs the development of supporting standards but the implementation of the standards. According to the analysis results, SDOs will continue improving pipeline safety and security standards by launching relevant standard development projects and encouraging research and development achievements transfer to standards.
Analysis and Testing of a 13Cr Pipeline to Demonstrate “Leak Before Break”
Authors: Andrews Robert M. , Millwood Neil , Tiku Sanjay , Pussegoda Nick , Hoekstra Menno , Smith Stephen 
Published: July 2013

As part of a safety case for a subsea 13Cr pipeline, the operator wished to demonstrate that if a circumferential through wall crack developed, the crack would remain stable as a leak rather than growing to a full bore rupture. An initial fracture mechanics analysis had suggested that the margins on crack length were too small to make such a “leak before break” argument. This paper reports an integrated programme of small scale testing, numerical modelling and full scale testing which showed that a leak before break case could be made.
13Cr martensitic steel generally shows excellent toughness at the service temperature, as does the super duplex weld metal that was used for the girth welds. However, as the pipeline had been installed by reeling, there was some concern that the toughness may have been reduced. Hence a programme of fracture toughness testing was designed to generate tearing resistance curves for both as-received and pre-strained parent material and weld metal. Deep and shallow through thickness notched specimen geometries were tested to explore the effect of constraint on the toughness. Finite element analysis was used to predict the stress intensity for a range of crack lengths, including the effects of misalignment. Non-linear analyses were used to estimate the limit load for the cracked pipe. The test results were used as input to tearing analyses to Level 3 of BS 7910. These showed that the tolerable length of a through wall crack exceeded the length of anticipated defects by a factor of at least two.
To confirm the fracture mechanics predictions, two full scale tests were carried out. These used pressure cycling to grow a through wall crack by fatigue. These cracks were stable under an internal pressure equal to the pipeline design pressure. The cracked specimens were then axially loaded to failure. Extensive tearing occurred before final failure at loads above those predicted by the fracture analysis, confirming the conservatism of the predictions.