Engineering Commons^™

High Temperature Thermodynamic, Mechanical And Kinetic Properties From First Principles, Anton Van Der Ven

Thermal Barrier Coatings IV

No abstract provided.

Demonstration Of Two Novel Methods For Residual Stress Management On Nial Bond Coats, Markus Krottenthaler, Karsten Durst, Mathias Goken

Thermal Barrier Coatings IV

No abstract provided.

Prediction Of The Cyclic Durability As A Function Of Cycle Duration And Temperature Of An Air Plasma Sprayed Coating Using Inelastic Strain, Eric H. Jordan, Shayan Ahmadian, Maurice Gell

Thermal Barrier Coatings IV

A detailed study of the failure mechanisms in an APS TBC was carried out involving over 1000 micrographs. As a result the kinetics of oxidation and rumpling were characterized. In addition it was found that the failure was always within the ceramic caused by progressive cracking. At approximately half the spallation life, crack linking became the dominant growth mode for cracks. This pattern of damage remained constants over the temperature range of 1066 °C to 1149 °C and for cycle durations of 0.5 hours to 50 hours. The change in temperature resulted in a variation in spallation life of a …

Use Of Liquid Pressure-Pulse Decay Permeameter In Experimental Evaluation Of Permeability In Wellbore Cement Under Geopressured Geothermal Conditions, Kolawole Bello, Mileva Radonjic

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Geopressured reservoirs in the northern Gulf of Mexico basin along the coast of Louisiana have been determined to be viable source of geothermal energy and potential sites for carbon sequestration, where CO2 can be utilized to induce convective flow of geofluids and enhance heat harvesting. These reservoirs are made of unconsolidated sandstone capped by shale layers and possess temperatures as high as 140⁰C. At high temperatures, cement strength retrogression occur when calcium silicate hydrate phase in hydrated cement converts to alpha dicalcium silicate hydrate phase. The higher the temperature, the quicker the rate of transformation of calcium silicate hydrate. The …

Nondestructive Thickness Measurements On Ebpvd Thermal Barrier Coatings By Using Terahertz Technique, Thomas Cosack, Jens Klier, Joachim Jonuscheit

Thermal Barrier Coatings IV

No abstract provided.

Biomaterial Testing Methodology For Long-Term In Vivo Applications: Silicon Carbide Corrosion Resistance, Biocompatibility And Hemocompatibility, Maysam Nezafati

USF Tampa Graduate Theses and Dissertations

Biomedical devices that function in-vivo offer a tremendous promise to improve the quality of life for many who suffer from disease and trauma. The most important consideration for these devices is that they interact with the physiological environment as designed without initiating a deleterious inflammatory response. ISO 10993 outlines the current international guideline for investigating the biocompatibility of such devices. Numerous groups report the use of ISO 10993 as the basis for their experimental evaluation of candidate materials for neuroprosthetics, as well as other biomedical devices, however most of these reports fail to completely comply with the standard. This leads …

Cost Performance Dynamics In Lean Production Leveling, Ahmed Deif, Hoda Elmaraghy

Industrial Technology and Packaging

Balancing of production systems is one of the main lean manufacturing principles as it reduces in-process storage and related forms of waste. A dynamic systems approach is proposed to investigate challenges of implementing production leveling and associated costs. A lean cell producing at takt time is modeled using system dynamics. The model captures various lean tools influencing production leveling and their implications. Comparative cost analysis between various leveling implementation policies for stochastic demand with multiple products is conducted. Results showed that determining the most feasible leveling policy is highly dictated by both the cost and limitations of capacity scalability. In …

Study Of Process Control Strategies For Biological Nutrient Removal In An Oxidation Ditch, Leslie Ann Knapp

USF Tampa Graduate Theses and Dissertations

Advanced wastewater treatment plants must meet permit requirements for organics, solids, nutrients and indicator bacteria, while striving to do so in a cost effective manner. This requires meeting day-to-day fluctuations in climate, influent flows and pollutant loads as well as equipment availability with appropriate and effective process control measures. A study was carried out to assess performance and process control strategies at the Falkenburg Road Advanced Wastewater Treatment Plant in Hillsborough County, Florida.

Three main areas for control of the wastewater treatment process are aeration, return and waste sludge flows, and addition of chemicals. The Falkenburg AWWTP uses oxidation ditches …

Separation Of Ash And Sulfur Dioxide During The 2011 Grímsvötn Eruption, E. D. Moxnes, N. I. Kristiansen, A. Stohl, L. Clarisse, A. J. Durant, K. Weber, A. Vogel

Michigan Tech Publications, Part 1

Modeling the transport of volcanic ash and gases released during volcanic eruptions is crucially dependent on knowledge of the source term of the eruption, that is, the source strength as a function of altitude and time. For the first time, an inversion method is used to estimate the source terms of both volcanic sulfur dioxide (SO2) and ash. It was applied to the explosive volcanic eruption of Grímsvötn, Iceland, in May 2011. The method uses input from the particle dispersion model, FLEXPART (flexible particle dispersion model), a priori source estimates, and satellite observations of SO2 or ash total columns from …

Heat Flow From A Buried Cylindrical Tank Partially Submerged In Groundwater, Robert Mckibbin, Shigeo Kimura

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

This study was motivated by the possibility of re-use of buried cylindrical tanks, once a facility for fuel storage at motor vehicle service stations (now relinquished by oil companies), but remaining for use as thermal reservoirs connected to space heating systems (e.g. for convenience stores) in Japan. The ground in which a tank is buried is assumed to be of uniform porosity and permeability, with a phreatic groundwater surface (water table) that may rise and fall, albeit slowly, over time. The ground and the water are subject to heating and cooling according to the season and weather conditions. Here, it …

Investigation Of Transpiration Cooling With Local Thermal Non-Equilibrium Model: Effects Of Different Thermal Boundary Conditions At The Porous-Fluid Interface, Zheng Huang, Yin-Hai Zhu, Pei-Xue Jiang, Yan-Bin Xiong

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

In this study, the main stream coupled with a porous medium with local thermal non-equilibrium assumption is analyzed. The flow inside the porous material is modelled using the Darcy–Brinkman–Forchheimer equation and the incompressible Navier-Stokes equations are solved for the main stream. Several couple conditions between the main flow temperature and the temperatures of the solid matrix and coolant flow at the fluid/porous interface is calculated. The results show that the Model C assumes the main flow temperature equals the solid phase temperature and the main flow heat flux is all imposed on the solid phase gives the most reasonable answer.

Effective Permeability Upscaling From Heterogenous To Homogenous Porous Media, Mehmet Cicek, Deepak Devegowda, Faruk Civan, Richard Sigal

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

An effective method to upscale permeability is presented to represent a heterogeneous reservoir with homogeneous permeability and porosity values. As a result, there is no need to deal with dual-porosity or dual-permeability models in reservoir simulations. Thus, the required CPU time for reservoir production and flow simulations is reduced significantly.

Modified Rhie-Chow / Piso Algorithm For Collocated Variable Finite Porous Media Flow Solvers, Markus Nordlund

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

A modified Rhie-Chow/ PISO segregated algorithm is proposed, whic by construction avoids the development of spurious oscillations in the solution fields for low Mach number flow in heterogeneous, isotropic porous media. The collocated variable finite volume based algorithm modifies the commonly used Rhie-Chow interpolation to maintain a strong pressure-velocity coupling when large discontinuous implicit momentum sources are present. This Redistributed Resistivity PISO algorithm is based on a redistribution of the flow resistivity over the neighboring grid cells to the discontinuity. The proposed algorithm is successfully verified against published data for the velocity and pressure for two cases. The robustness of …

Pressure Transient Characteristics Of Multi-Stage Fractured Horizontal Wells In Shale Gas Reservoirs With Consideration Of Multiple Mechanisms, Jingjing Guo, Liehui Zhang, Haitao Wang

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The approach of multi-stage fractured horizontal wells (MFHWs) has been proven an efficient technology for successful development of shale gas reservoirs. Together with multiple gas flow mechanisms, the existence of multiple hydraulic fractures further complicates the gas flowing problem in shale gas reservoirs. Understanding pressure transient dynamics of MFHWs in shale gas reservoirs is of great importance to provide a perception into long-term pressure dynamics forecast as well as to estimate relevant reservoir and fracturing parameters. This paper presents a comprehensive seepage model to investigate the characteristics of pressure transient responses of a horizontal well intercepted by multiple finitely conductive …

Turbulence In Porous Media: Some Fundamental Questions Addressed By Dns Solutions, Marc Florian Uth, Y. Jin, A. V. Kuznetsov, H. Herwig

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

In a generic porous matrix built by a large number of rectangular bars the flow is determined numerically by a DNS approach. Turbulent flow is thus simulated avoiding modelling in order to decide whether turbulent structures with scales much larger than the pore scale exist. So far only under-resolved DNS solutions are determined from which, however, definite conclusions with respect to the maximum turbulent length scale can be drawn.

Numerical Solutions Of Non-Linear Fractional Transport Models In Unconventional Hydrocarbon Reservoirs Using Variational Iteration Method, Nadeen Malik, Iftikhar Ali, Bilal Chanane

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Unconventional hydrocarbon reservoirs, such as, shale gas deposits, offer a new source of energy resources. These reservoirs consist of tight porous rocks which are characterized by nano-scale size porous networks with ultra-low permeability. The mathematical modeling of phenomena through such tight porous media provides its own challenges. In this study, we consider a relatively new approach by modeling the transport of gas by the time-fractional advection-diffusion equation,

Wall Thickness Optimization Of A Transpiration-Cooled Sharp Leading Edge At Atmospheric Re-Entry, Christian Dittert

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The purpose of this paper is to find the necessary cooling mass flow for a defined wall thickness distribution, which allows a selective cooling for an acceptable temperature range of the sharp leading edge of an atmospheric re-entry vehicle. Due to the angle of attack during the re-entry flight the pressure at the top side is lower than the pressure at the bottom side. However, the highest heat load occurs at the stagnation point at which also the maximum pressure is effective. The efficiency of a transpiration cooling depends on the mass flow rate of the coolant. The cooling mass …

Comparison Of Volume-Average Simulation And Pore-Scale Simulation Of Thermal Radiation And Natural Convection In High Temperature Packed Beds, Le Zhang, Ruina Xu, Peixue Jiang

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The phenomenon of natural convection and thermal radiation heat transfer in fluid-saturated high temperature packed beds has been widely studied due to its various applications ranging from solar collectors to high temperature gas cooled reactor. With the local thermal non-equilibrium model, the majority of the numerical simulation studies on natural convection and radiation heat transfer in fluid-saturated porous media have limits. In these studies the internal heat transfer coefficients have always been calculated as the existing formulas, which were obtained by the experiments of forced convection in porous media [1-2]. However, natural convection heat transfer in porous media is dominated …

Three Dimensional Heat And Mass Transfer In Capillary Evaporator, Laetitia Mottet, Typhaine Coquard, Marc Prat

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Heat and mass transfer inside the porous wick of a capillary evaporator is studied using a mixed porenetwork model. The impact of the thermal conductivity of the wick on the overheating limit (defined as the difference between the maximum temperature at the top of the metallic casing and the saturated temperature), breakthrough (which occurs when the vapor reaches the wick inlet) and the parasitic heat flux lost by conduction at the entrance of the wick (which decreases the efficiency of the evaporator) is investigated. The study suggests a bilayer wick as a possible better design to optimize the performance of …

Onset Of Double Diffusive Reaction-Convection In An Anisotropic Porous Layer With Internal Heat Source, S.N. Gaikwad, M. Dhanraj

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The effect of internal heat source on the onset of double diffusive reaction-convection in an anisotropic porous layer subjected to chemical equilibrium on the boundaries is investigated analytically using linear stability analyses. The linear analysis is based on the usual normal mode method. The Darcy model is employed for the momentum equation. The effect of internal Rayleigh number, Damkohler number, mechanical anisotropy parameter and thermal anisotropy parameter on the stationary and oscillatory convection is shown graphically. It is found that the effect of internal Rayleigh number and mechanical anisotropy parameter have destabilizing effect, while the thermal anisotropy parameter has stabilizing …

Evaluating Deformation Behavior Of A Tbc-System During Thermal Gradient Mechanical Fatigue By Means Of High Energy X-Ray Diffraction, M. Bartsch, J. Wischek, C. Meid, K. Knipe, A. Manero, S. Raghavan, A. M. Karlsson, J. Okasinski, J. Almer

Thermal Barrier Coatings IV

No abstract provided.

Manufacture Of Silicide Coatings For The Protection Of Niobium Alloys Against High Temperature Oxidation, M. Vilasi, S. Matheieu, S. Knittel, L. Portebois, T. Katrina, C. Rapin, C. Petitjean, P. J. Panteix, S. Drawin

Thermal Barrier Coatings IV

At the moment, silicide coatings provide the best protection against high temperature oxidation for niobium alloys. These are envisaged for replacing nickel base alloys currently used in the hot section of turbo-engines. Silicides confer higher protectiveness to Nb base system when compared to the environmental resistance presented by Nb alloys coated with aluminides. One major advantage of silicides is probably the great number of possibilities for modifying their composition as well as their crystallographic structure. Thus, many elemental substitutions were performed over the past 20 years in order to optimize their performances in terms of oxidation resistance. The works performed …

Lifetime Of Environmental/Thermal Barrier Coatings Deposited On An Nb/Nb5si3- Based Alloy With Feb-Modified M7si6-Based Bond Coat, Reinhold Braun, Annika Lange, Uwe Schulz, Leo Portebois, Stephane Mathieu, Michael Vilasi, Stefan Drawin

Thermal Barrier Coatings IV

To enhance the performance of aircraft engines, high temperature materials are required being capable to operate at temperatures significantly higher than the temperature limit of about 1150°C approached for Ni-based superalloys currently employed. Nb/Nb5Si3-based composites are promising candidates for turbine engine applications at temperatures up to 1300°C, exhibiting balanced mechanical properties and reduced density compared to Ni-based superalloys [1]. To use these composites in gas turbine combustion atmosphere, environmental/thermal barrier coatings (E/TBCs) are required to protect them against heat, degradation in flowing water vapour and chemical attack of calcium-magnesium-alumino-silicate (CMAS).

Simulations Of Fracture In Coatings With Complex Microstructures, Mathew R. Begley, William Pro, Rone Kwei Lim, Linda Petzold

Thermal Barrier Coatings IV

No abstract provided.

Lifetime Assessment Tools For Thermal Barrier Systems, Jean Louis Chaboche, Frederic Feyel, Martine Poulain, Noemie Rakotamalala, Arjen Roos, Jean Roch Vaunois, Arnaud Longuet, Pascale Kanaoute

Thermal Barrier Coatings IV

No abstract provided.

Reliable Measurement Of Mechanical Tbc Properties For Quality Control And Life Prediction, Peter Wittig, Stefan Lampenscherf, Uwe Rettig, Matthias Oechsner

Thermal Barrier Coatings IV

No abstract provided.

High Temperature Environmental Resistance Of Mo-Si-B Alloys And Coatings, John H. Perepezko

Thermal Barrier Coatings IV

No abstract provided.

Mechanical Stability Limits Of Bi-Layer Thermal Barrier Coatings, Mario Rudolphi, Mathias Galetz, Michael Schutze, Martin Frommherz, Alfred Scholz, Mathias Oechsner, Emine Bakan, Robert Vassen, Werner Stamn

Thermal Barrier Coatings IV

Thermal barrier coatings based on yttria stabilized zirconia (YSZ) have reached a state in development, where a further increase in lifetime and/or maximum operating temperature has become more and more difficult. Nevertheless, the demand for even higher operating temperatures is persisting, and it is pushing the YSZ-based thermal barrier coatings to and beyond their limit. Especially phase instabilities of YSZ at temperatures above 1200°C lead to a fast deterioration of the ceramic top coating. Consequently, the search for new materials with low thermal conductivity, relatively low coefficient of thermal expansion and phase stability at temperatures well above 1200°C was started, …

Specific Failure Modes Of Ni-Base Superalloys And Tbcs Under A Simulated Combustion Gas Atmosphere, Mazaku Okazaki, Satoshi Yamagishi, Y. Hayashi

Thermal Barrier Coatings IV

No abstract provided.

Nasa’S Advanced Environmental Barrier Coatings Development For Sic/Sic Ceramic Matrix Composites: Understanding Cmas Degradations And Resistance, Dongming Zhu

Thermal Barrier Coatings IV

No abstract provided.