Nihad Dukhan | University of Detroit Mercy (original) (raw)
Papers by Nihad Dukhan
Journal of Materials Research, 2020
Historically, porous metals have focused on structural applications where specific stiffness and ... more Historically, porous metals have focused on structural applications where specific stiffness and strength were optimized, using conventional casting, sintering, cutting, machining and joining techniques to create ductile and strong porous metallic structure. For such load-bearing applications, porous metals are studied and used in many sectors, e.g., transportation, architecture, and medicine (for bone-replacement implants). This special issue of the Journal of Materials Research contains articles that were accepted in response to an invitation for manuscripts.
Journal of Materials Research, 2020
Structure-processing relationships of freeze-cast iron foams fabricated with various solidificati... more Structure-processing relationships of freeze-cast iron foams fabricated with various solidification rates and post-casting heat treatment J. Mater.
Metal foam is a relatively new class of porous media. The internal morphology of the foam is comp... more Metal foam is a relatively new class of porous media. The internal morphology of the foam is composed of connected cells each having many ligaments that form a web. In addition, metal foam has very high porosity (often greater than 90%) and a large surface area density. These properties are exploited in many applications, e.g., filtration, heat exchange and reactors. Flow regimes, and transition from one to another, are critical for understanding energy dissipation mechanisms for flow through the foam. While this topic is well studied in traditional porous media, e.g., packed beds, it is not well understood for foam-like porous media such as metal, graphite and polymeric foams. The choice of an appropriate characteristic length for metal foam has also varied among researchers. Pressure drop characteristics such as the permeability and form/inertial drag coefficient are very divergent for metal foam. The current study is to shed some light on the above issues. In particular, a large ...
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students ’ soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his
2007 Annual Conference & Exposition Proceedings
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students' soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his BS, MS, and Ph.D. degrees in Mechanical Engineering from the University of Toledo.
Fluid flow in porous media is found in numerous processes and applications of vital engineering i... more Fluid flow in porous media is found in numerous processes and applications of vital engineering interest, e.g., storage of nuclear waste, heat exchangers, ground water pollution and chemical reactors. Often, the porous medium is confined by solid boundaries for containment. These impermeable boundaries give rise to shear stress and boundary layers. The Brinkman-extended Darcy equation governs the momentum transport due to Newtonian fluid flow in such porous-media flow situations. Metal foam, especially aluminum-based, has gained a lot of academic and industrial interest over the past few years. The significance of metal foam is due to its low density (or, high porosity: 75 % to 95 %.), high thermal conductivity, interconnectivity of its solid ligaments and large surface area density. Metal foam applications include heat exchange system and chemical reactors. In these systems, the foam is usually cylindrical in shape and is contained in a cylindrical tube. The fluid flow in such syst...
QScience Proceedings, 2015
In engineering, thermodynamics is the science of energy. This includes traditional and alternativ... more In engineering, thermodynamics is the science of energy. This includes traditional and alternative sources of energy and energy availability, conversion and transmission. Practical engineering issues such as the efficiency of thermodynamic processes and systems are also covered in engineering thermodynamics courses. As the world is becoming more aware of the impeding energy crisis, a rounded understanding of thermodynamics by the engineers of 2020 is vital for addressing this global issue. Despite the importance of the subject, past and current engineering students worldwide struggle with thermodynamics as indicated by the pertinent literature. Student's difficulties with thermodynamics have been reported in several European countries, the US, Australia and India. Indeed, understanding the root causes of problems with teaching/learning thermodynamics is a requisite first step toward any solution, e.g., a design of effective new instructional strategies, curricula and textbooks. This paper provides a concise account of the pertinent literature, and analyzes this literature in order to accurately frame the problems of learning (and teaching) thermodynamics. The paper describes methods used for probing these problems and attempts to solve them.
QScience Proceedings, 2015
The importance and nature of non-technical skills for future engineers are described in this pape... more The importance and nature of non-technical skills for future engineers are described in this paper. The discourses of educational, industrial and governmental organizations concerning these skills are summarized. Related issues such as nature of the knowledge-based economy, the nature and need for innovation, entrepreneurship, working in teams and the need for life-long learning in relation to non-technical skills are also discussed. The rubric that was used to assess the awareness of engineering students of these skills is presented, along with the results of the assessment. In general, the results show that the vast majority of students showed a great deal of awareness and importance of these skills for their futures as engineers. The assessment for establishing the existing knowledge level of students is critical for guiding future curricular materials geared toward enhancing some of the non-technical skills of future engineers. Particularly, the results suggest any new curricular materials must enhanc...
Volume 10: Heat and Mass Transport Processes, Parts A and B, 2011
Contemporary porous media that are used in cooling designs include metal and graphite foam. These... more Contemporary porous media that are used in cooling designs include metal and graphite foam. These materials are excellent heat transfer cores due to their large surface area density and the relatively high conductivity of the solid phase. Engineering models for convection heat transfer in such media are needed for thermal system design. When the cooling fluid has a low conductivity, e.g., air, its conduction can be set to zero. Engineering analysis for the fully-developed convection heat transfer inside a confined cylindrical isotropic porous media subjected to constant heat flux is presented. The analysis considers the Darcy flow model and high Pe´clet number. The non-local-thermal equilibrium equations are significantly simplified and solved. The solid and fluid temperatures decay in what looks like an exponential fashion as the distance from the heated wall increases. The effects of the Biot number and the Darcy number are investigated. The results are in qualitative agreement wi...
2007 Annual Conference & Exposition Proceedings
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students' soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his BS, MS, and Ph.D. degrees in Mechanical Engineering from the University of Toledo.
2011 ASEE Annual Conference & Exposition Proceedings
It is perceived that the majority of capstone projects for senior mechanical engineering students... more It is perceived that the majority of capstone projects for senior mechanical engineering students usually deals with designs that do not include issues related to thermal sciences; i.e., thermodynamics, heat transfer and fluid mechanics. This may lead students to falsely think that the thermal sciences are usually not critical in practical designs since the capstone course is supposed to mimic actual engineering designs in the industry. The thinking that thermal issues are incidental is dangerous since vital industries-oil, electronics, power generation and conversion and cryogenics, to name but a few-rely heavily on thermal design. Actually one of the biggest current challenges is energy-its sources and conservation, which feeds into any kind of sustainable design. Lack of thermal projects in capstone courses also may prevent interested students from making thermal sciences their focal area and future career. The relatively low number of thermal science projects in capstone courses may be due to the fact that the instructors assigned to teach these courses are specialists in other areas of mechanical engineering. This paper explores these issues through surveying capstone projects in a number of universities. It probes capstone-teaching faculty and reflects on their attitudes toward thermal-science projects. The paper attempts to determine if there is a lack of thermalscience projects in capstone courses and if so what the reasons are. A third purpose of the paper was to probe the feelings of non-thermal faculty teaching capstone towards thermal projects, and whether or under what conditions they would be willing to offer more thermal design projects in the future. The paper also poses a few general questions regarding the role of thermal sciences in capstone design and suggests a strategic way for implementing more thermal science capstone projects.
International Journal for Service Learning in Engineering, Humanitarian Engineering and Social Entrepreneurship, 2007
This paper describes the implementation and the impact of a service-learning project in a heat tr... more This paper describes the implementation and the impact of a service-learning project in a heat transfer course for undergraduate engineering students. The students visited low-income households in the Detroit area and installed insulation materials on doors and windows thereby conserving energy and reducing heating costs during the cold months. The students collected information about the materials, dimensions, and relevant engineering parameters. They used the information to calculate the resulting dollar amount of energy savings. There were interactions with a university office in charge of assisting the faculty in using service learning by developing course-relevant community-service projects. There was collaboration with a nonprofit organization that promotes the development of resource efficient homes through training and technical assistance. Data were first gathered about the students’ awareness and attitudes regarding the relationship between engineering work and society. St...
International Journal of Heat and Mass Transfer, 2016
Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surfa... more Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area density. The open flow area is copious compared to the ligament size. These properties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paper presents experimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 pores per inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 pores per inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.
33rd Aerospace Sciences Meeting and Exhibit, 1995
A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This ... more A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This technique was applied to a series of ice shapes that were grown in the NASA Lewis Icing Research Tunnel on fiat plares. Nine fiat plares, 18 inches square, were obtained from which aluminum castings were made that gave good ice shape characterizations. Test strips taken from these plates were outfitted with heat flux gages, such that when placed in a dry wind tunnel, can be used to experimentally map out the
Defect and Diffusion Forum, 2015
Flow in porous media occurs in many naturally-occurring and engineered systems. One of the key pr... more Flow in porous media occurs in many naturally-occurring and engineered systems. One of the key properties for understanding the fluid flow and pressure drop in porous media is permeability, which is varies widely among researchers. The current work presents systematic experimental data for packed spheres of uniform size (3 mm) having a porosity of 36.6% subjected to water flow. The experiments covered a sufficiently broad range of flow Reynolds number such that all flow regimes are encountered: pre-Darcy, Darcy, Forchheimer and Turbulent. The pre-Darcy regime is very scarce or non-present in the literature. As a necessary initial step, flow regimes were identified and different permeabilities exhibited by the porous medium in each flow regime were calculated. The length scales in defining the Reynolds number included the diameter of the sphere and the square root of the various permeabilities in order to study the transitional Reynolds numbers among the flow regimes. It is shown tha...
This work presents a reduced mathematical model using a practical numerical formulation of the th... more This work presents a reduced mathematical model using a practical numerical formulation of the thermal behavior of an Integrated Power Electronics Module (IPEM). This model is based on the expanded Lumped Thermal Capacitance Method (LTCM), in which the number of variables involved in the analysis of heat transfer is reduced only to time. By applying this procedure a simple, non-spatial, but highly non-linear model is obtained. Transient results of the model were validated using FLOTHERM 3.1 TM , a thermal analysis software tool. Two experimental setup , for low-and high-speed thermal response, were developed. Comparisons between thermal model results and experimental data are also presented to demonstrate the need to obtain the electrical performance and to make the electrothermal coupling. The development of this model presents an alternative to reduce the complexity level developed in commercial multidimensional and transient thermal analysis software tools.
Experimental Thermal and Fluid Science, 2015
ABSTRACT Characteristics of oscillating water flow in open-cell metal foam were obtained experime... more ABSTRACT Characteristics of oscillating water flow in open-cell metal foam were obtained experimentally. The foam had 20 pores per inch and a porosity of 87.6%. Three flow displacements 74.35, 97.2 and 111.53 mm were applied in the flow frequency range 0.116 to 0.696 Hz. Steady-state experiment was also conducted and the permeability and form/inertial drag coefficient were obtained. The range of flow velocity covered Darcy and Forchheimer flow regimes. The effect of flow displacement and frequency on important variables is presented and discussed. The appropriately defined friction factor correlated well with the Reynolds number for steady-state and oscillating flows, with the friction factor for oscillating flow being higher. The current results were compared to other studies from the literature employing oscillating air and water in various kinds of porous media. Some agreements and disagreements are stated and discussed.
34th Aerospace Sciences Meeting and Exhibit, 1996
Proceedings. Frontiers in Education. 36th Annual Conference, 2006
A thermodynamics project for a small class of Ford Motor Company's students, working towards ... more A thermodynamics project for a small class of Ford Motor Company's students, working towards a BS degree in mechanical engineering, is described. It consisted of identifying one of the negative impacts of energy conversions on the environment, describing it, its cause, pollutants and its effect on the environment. The students picked acid rain, greenhouse effect and smog formation. The assignment put one of the topics of thermodynamics in perspective and related it directly to what the students are familiar with in their workplace making a real-life connection. The project also partially fulfilled one of the targeted outcomes for accreditation: awareness of environmental issues. The benefits of the project were assessed by analyzing their reports and by using a survey. Both methods showed that the students learned a great deal about the topic they had to write about, and that they would take the environmental effects as a factor when making engineering decisions
Procedia Materials Science, 2014
A hybrid material created by mechanically combining polymers and aluminum foams is modeled and an... more A hybrid material created by mechanically combining polymers and aluminum foams is modeled and analyzed. The hybrid is manufactured by injection molding a polymer (polypropylene and acetal) into the open cells of Duocel® aluminum foam. Prior experimental work revealed that the combination of the polymer and the metal foam yields a hybrid that is stiffer than the polymer alone but has a reduced ultimate tensile strength. A finite element model using a tetrakaidecahedral unit cell is used to model the metal foam ligaments with the polymer occupying the remaining space. The resulting conclusions are that the aluminum ligaments oriented along the load direction cause an increase in stiffness but ligaments oriented laterally cause stress concentration that yield lower strength. The finite element model is used to give both qualitative and quantitative explanations of the physics of the interrelations between the metal foam and the polymer.
Journal of Materials Research, 2020
Historically, porous metals have focused on structural applications where specific stiffness and ... more Historically, porous metals have focused on structural applications where specific stiffness and strength were optimized, using conventional casting, sintering, cutting, machining and joining techniques to create ductile and strong porous metallic structure. For such load-bearing applications, porous metals are studied and used in many sectors, e.g., transportation, architecture, and medicine (for bone-replacement implants). This special issue of the Journal of Materials Research contains articles that were accepted in response to an invitation for manuscripts.
Journal of Materials Research, 2020
Structure-processing relationships of freeze-cast iron foams fabricated with various solidificati... more Structure-processing relationships of freeze-cast iron foams fabricated with various solidification rates and post-casting heat treatment J. Mater.
Metal foam is a relatively new class of porous media. The internal morphology of the foam is comp... more Metal foam is a relatively new class of porous media. The internal morphology of the foam is composed of connected cells each having many ligaments that form a web. In addition, metal foam has very high porosity (often greater than 90%) and a large surface area density. These properties are exploited in many applications, e.g., filtration, heat exchange and reactors. Flow regimes, and transition from one to another, are critical for understanding energy dissipation mechanisms for flow through the foam. While this topic is well studied in traditional porous media, e.g., packed beds, it is not well understood for foam-like porous media such as metal, graphite and polymeric foams. The choice of an appropriate characteristic length for metal foam has also varied among researchers. Pressure drop characteristics such as the permeability and form/inertial drag coefficient are very divergent for metal foam. The current study is to shed some light on the above issues. In particular, a large ...
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students ’ soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his
2007 Annual Conference & Exposition Proceedings
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students' soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his BS, MS, and Ph.D. degrees in Mechanical Engineering from the University of Toledo.
Fluid flow in porous media is found in numerous processes and applications of vital engineering i... more Fluid flow in porous media is found in numerous processes and applications of vital engineering interest, e.g., storage of nuclear waste, heat exchangers, ground water pollution and chemical reactors. Often, the porous medium is confined by solid boundaries for containment. These impermeable boundaries give rise to shear stress and boundary layers. The Brinkman-extended Darcy equation governs the momentum transport due to Newtonian fluid flow in such porous-media flow situations. Metal foam, especially aluminum-based, has gained a lot of academic and industrial interest over the past few years. The significance of metal foam is due to its low density (or, high porosity: 75 % to 95 %.), high thermal conductivity, interconnectivity of its solid ligaments and large surface area density. Metal foam applications include heat exchange system and chemical reactors. In these systems, the foam is usually cylindrical in shape and is contained in a cylindrical tube. The fluid flow in such syst...
QScience Proceedings, 2015
In engineering, thermodynamics is the science of energy. This includes traditional and alternativ... more In engineering, thermodynamics is the science of energy. This includes traditional and alternative sources of energy and energy availability, conversion and transmission. Practical engineering issues such as the efficiency of thermodynamic processes and systems are also covered in engineering thermodynamics courses. As the world is becoming more aware of the impeding energy crisis, a rounded understanding of thermodynamics by the engineers of 2020 is vital for addressing this global issue. Despite the importance of the subject, past and current engineering students worldwide struggle with thermodynamics as indicated by the pertinent literature. Student's difficulties with thermodynamics have been reported in several European countries, the US, Australia and India. Indeed, understanding the root causes of problems with teaching/learning thermodynamics is a requisite first step toward any solution, e.g., a design of effective new instructional strategies, curricula and textbooks. This paper provides a concise account of the pertinent literature, and analyzes this literature in order to accurately frame the problems of learning (and teaching) thermodynamics. The paper describes methods used for probing these problems and attempts to solve them.
QScience Proceedings, 2015
The importance and nature of non-technical skills for future engineers are described in this pape... more The importance and nature of non-technical skills for future engineers are described in this paper. The discourses of educational, industrial and governmental organizations concerning these skills are summarized. Related issues such as nature of the knowledge-based economy, the nature and need for innovation, entrepreneurship, working in teams and the need for life-long learning in relation to non-technical skills are also discussed. The rubric that was used to assess the awareness of engineering students of these skills is presented, along with the results of the assessment. In general, the results show that the vast majority of students showed a great deal of awareness and importance of these skills for their futures as engineers. The assessment for establishing the existing knowledge level of students is critical for guiding future curricular materials geared toward enhancing some of the non-technical skills of future engineers. Particularly, the results suggest any new curricular materials must enhanc...
Volume 10: Heat and Mass Transport Processes, Parts A and B, 2011
Contemporary porous media that are used in cooling designs include metal and graphite foam. These... more Contemporary porous media that are used in cooling designs include metal and graphite foam. These materials are excellent heat transfer cores due to their large surface area density and the relatively high conductivity of the solid phase. Engineering models for convection heat transfer in such media are needed for thermal system design. When the cooling fluid has a low conductivity, e.g., air, its conduction can be set to zero. Engineering analysis for the fully-developed convection heat transfer inside a confined cylindrical isotropic porous media subjected to constant heat flux is presented. The analysis considers the Darcy flow model and high Pe´clet number. The non-local-thermal equilibrium equations are significantly simplified and solved. The solid and fluid temperatures decay in what looks like an exponential fashion as the distance from the heated wall increases. The effects of the Biot number and the Darcy number are investigated. The results are in qualitative agreement wi...
2007 Annual Conference & Exposition Proceedings
Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing ... more Mercy, where he teaches courses in heat transfer, thermodynamics and energy systems. His ongoing pedagogical interests include developing undergraduate research programs, service-learning programs, and assessing their impact on students' soft skills. His technical research areas are advanced cooling technologies for high-power devices. Dr. Dukhan earned his BS, MS, and Ph.D. degrees in Mechanical Engineering from the University of Toledo.
2011 ASEE Annual Conference & Exposition Proceedings
It is perceived that the majority of capstone projects for senior mechanical engineering students... more It is perceived that the majority of capstone projects for senior mechanical engineering students usually deals with designs that do not include issues related to thermal sciences; i.e., thermodynamics, heat transfer and fluid mechanics. This may lead students to falsely think that the thermal sciences are usually not critical in practical designs since the capstone course is supposed to mimic actual engineering designs in the industry. The thinking that thermal issues are incidental is dangerous since vital industries-oil, electronics, power generation and conversion and cryogenics, to name but a few-rely heavily on thermal design. Actually one of the biggest current challenges is energy-its sources and conservation, which feeds into any kind of sustainable design. Lack of thermal projects in capstone courses also may prevent interested students from making thermal sciences their focal area and future career. The relatively low number of thermal science projects in capstone courses may be due to the fact that the instructors assigned to teach these courses are specialists in other areas of mechanical engineering. This paper explores these issues through surveying capstone projects in a number of universities. It probes capstone-teaching faculty and reflects on their attitudes toward thermal-science projects. The paper attempts to determine if there is a lack of thermalscience projects in capstone courses and if so what the reasons are. A third purpose of the paper was to probe the feelings of non-thermal faculty teaching capstone towards thermal projects, and whether or under what conditions they would be willing to offer more thermal design projects in the future. The paper also poses a few general questions regarding the role of thermal sciences in capstone design and suggests a strategic way for implementing more thermal science capstone projects.
International Journal for Service Learning in Engineering, Humanitarian Engineering and Social Entrepreneurship, 2007
This paper describes the implementation and the impact of a service-learning project in a heat tr... more This paper describes the implementation and the impact of a service-learning project in a heat transfer course for undergraduate engineering students. The students visited low-income households in the Detroit area and installed insulation materials on doors and windows thereby conserving energy and reducing heating costs during the cold months. The students collected information about the materials, dimensions, and relevant engineering parameters. They used the information to calculate the resulting dollar amount of energy savings. There were interactions with a university office in charge of assisting the faculty in using service learning by developing course-relevant community-service projects. There was collaboration with a nonprofit organization that promotes the development of resource efficient homes through training and technical assistance. Data were first gathered about the students’ awareness and attitudes regarding the relationship between engineering work and society. St...
International Journal of Heat and Mass Transfer, 2016
Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surfa... more Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area density. The open flow area is copious compared to the ligament size. These properties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paper presents experimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 pores per inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 pores per inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.
33rd Aerospace Sciences Meeting and Exhibit, 1995
A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This ... more A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This technique was applied to a series of ice shapes that were grown in the NASA Lewis Icing Research Tunnel on fiat plares. Nine fiat plares, 18 inches square, were obtained from which aluminum castings were made that gave good ice shape characterizations. Test strips taken from these plates were outfitted with heat flux gages, such that when placed in a dry wind tunnel, can be used to experimentally map out the
Defect and Diffusion Forum, 2015
Flow in porous media occurs in many naturally-occurring and engineered systems. One of the key pr... more Flow in porous media occurs in many naturally-occurring and engineered systems. One of the key properties for understanding the fluid flow and pressure drop in porous media is permeability, which is varies widely among researchers. The current work presents systematic experimental data for packed spheres of uniform size (3 mm) having a porosity of 36.6% subjected to water flow. The experiments covered a sufficiently broad range of flow Reynolds number such that all flow regimes are encountered: pre-Darcy, Darcy, Forchheimer and Turbulent. The pre-Darcy regime is very scarce or non-present in the literature. As a necessary initial step, flow regimes were identified and different permeabilities exhibited by the porous medium in each flow regime were calculated. The length scales in defining the Reynolds number included the diameter of the sphere and the square root of the various permeabilities in order to study the transitional Reynolds numbers among the flow regimes. It is shown tha...
This work presents a reduced mathematical model using a practical numerical formulation of the th... more This work presents a reduced mathematical model using a practical numerical formulation of the thermal behavior of an Integrated Power Electronics Module (IPEM). This model is based on the expanded Lumped Thermal Capacitance Method (LTCM), in which the number of variables involved in the analysis of heat transfer is reduced only to time. By applying this procedure a simple, non-spatial, but highly non-linear model is obtained. Transient results of the model were validated using FLOTHERM 3.1 TM , a thermal analysis software tool. Two experimental setup , for low-and high-speed thermal response, were developed. Comparisons between thermal model results and experimental data are also presented to demonstrate the need to obtain the electrical performance and to make the electrothermal coupling. The development of this model presents an alternative to reduce the complexity level developed in commercial multidimensional and transient thermal analysis software tools.
Experimental Thermal and Fluid Science, 2015
ABSTRACT Characteristics of oscillating water flow in open-cell metal foam were obtained experime... more ABSTRACT Characteristics of oscillating water flow in open-cell metal foam were obtained experimentally. The foam had 20 pores per inch and a porosity of 87.6%. Three flow displacements 74.35, 97.2 and 111.53 mm were applied in the flow frequency range 0.116 to 0.696 Hz. Steady-state experiment was also conducted and the permeability and form/inertial drag coefficient were obtained. The range of flow velocity covered Darcy and Forchheimer flow regimes. The effect of flow displacement and frequency on important variables is presented and discussed. The appropriately defined friction factor correlated well with the Reynolds number for steady-state and oscillating flows, with the friction factor for oscillating flow being higher. The current results were compared to other studies from the literature employing oscillating air and water in various kinds of porous media. Some agreements and disagreements are stated and discussed.
34th Aerospace Sciences Meeting and Exhibit, 1996
Proceedings. Frontiers in Education. 36th Annual Conference, 2006
A thermodynamics project for a small class of Ford Motor Company's students, working towards ... more A thermodynamics project for a small class of Ford Motor Company's students, working towards a BS degree in mechanical engineering, is described. It consisted of identifying one of the negative impacts of energy conversions on the environment, describing it, its cause, pollutants and its effect on the environment. The students picked acid rain, greenhouse effect and smog formation. The assignment put one of the topics of thermodynamics in perspective and related it directly to what the students are familiar with in their workplace making a real-life connection. The project also partially fulfilled one of the targeted outcomes for accreditation: awareness of environmental issues. The benefits of the project were assessed by analyzing their reports and by using a survey. Both methods showed that the students learned a great deal about the topic they had to write about, and that they would take the environmental effects as a factor when making engineering decisions
Procedia Materials Science, 2014
A hybrid material created by mechanically combining polymers and aluminum foams is modeled and an... more A hybrid material created by mechanically combining polymers and aluminum foams is modeled and analyzed. The hybrid is manufactured by injection molding a polymer (polypropylene and acetal) into the open cells of Duocel® aluminum foam. Prior experimental work revealed that the combination of the polymer and the metal foam yields a hybrid that is stiffer than the polymer alone but has a reduced ultimate tensile strength. A finite element model using a tetrakaidecahedral unit cell is used to model the metal foam ligaments with the polymer occupying the remaining space. The resulting conclusions are that the aluminum ligaments oriented along the load direction cause an increase in stiffness but ligaments oriented laterally cause stress concentration that yield lower strength. The finite element model is used to give both qualitative and quantitative explanations of the physics of the interrelations between the metal foam and the polymer.