Arman Molki

Ductile Failure Modelling of Expanded Aluminium Tubes With Embedded Circular Holes

A common technology used for well completion in the oil and gas industry is the solid expandable tubular technology, where a metal pipe is expanded radially towards the well bore. A challenge in this technology is to assess the mechanical integrity of the pipes during the expansion process. In this paper the ductile failure behavior of mechanically expanded aluminum tubes was studied experimentally and numerically. The expansion of the tubes was performed mechanically by using a conical mandrel with the objective to study the failure mode that governs the expansion process of this material. To localize the failure the tubes were drilled with circular holes. The fractured surfaces of failed expanded tubes were examined and revealed a flat ductile dimple rupture characteristic. A finite element model, which is based on continuum damage mechanics, is developed to mimic the experiments. The model also predicts ductile crack propagation and failure in the expanded tubes with embedded holes very well making it a suitable tool for studying the tubular expansion process and for optimizing the expansion tools used in this process.Copyright

Measurement of fluid velocity development behind a circular cylinder using particle image velocimetry (PIV)

In this paper we present a non-intrusive experimental approach for obtaining a two-dimensional velocity distribution around a 22 mm diameter circular cylinder mounted in a water tunnel. Measurements were performed for a constant Reynolds number of 7670 using a commercial standard particle image velocimetry (PIV) system. Different flow patterns generated behind the circular cylinder are discussed. Both instantaneous and time-averaged velocity distributions with corresponding streamlines are obtained. Key concepts in fluid mechanics, such as contra-rotating vortices, von Karman vortex street, and laminar-turbulent flow, are discussed. In addition, brief historical information pertaining to the development of flow measurement techniques—in particular, PIV—is described.

Experimental Study of Water Entry and Exit of a Circular Cylinder at Free Surface: An Educational Approach

This paper outlines a proposed experimental setup for characterizing the vertical motion of a horizontal circular cylinder through a free surface. Both water entry and exit are studied. The proposed experimental setup will enhance the student’s learning of the hydrodynamic impact phenomena. The experimental study is based on the flow visualization of free surface and surrounding water during the cylinder’s motion. The fluid flow phenomenon around the submerged cylinder is investigated using high-speed digital imaging and Particle Image Velocimetry (PIV). The proposed experiment is used as part of an undergraduate mechanical engineering fluid mechanics course taught at a university, which aims to educate young male and female engineers for the local oil and gas industry and particularly for the companies involved in sponsoring the institution. The details of the flow visualization system and teaching strategy for implementing this experiment in a Mechanical Engineering curriculum is discussed.Copyright

Characterization of Air-Entrainment in a Plunging Water Jet System Using Image Processing: An Educational Approach

This paper outlines a proposed experimental setup and image processing techniques using MATLAB for the characterization of the average dynamic behavior of the air/water mixture under the free surface of water penetrated by a plunging jet. The proposed setup focuses on the dynamics of air entrainment below the free surface and the identification of the major regimes related to the entrainment process of bubbles in water, namely: (a) no-entrainment, (b) incipient entrainment, (c) intermittent entrainment, and (d) continuous entrainment. The experimental setup allows students to observe the flow behavior below the free liquid surface and determine the penetration depth of the bubble plumes using image processing techniques in MATLAB. The focal point of the experiment is image analysis for qualitative and quantitative characterization of the bubble plume.© 2011 ASME

Teaching the Concept of Bernoulli Equation Using Particle Image Velocimetry (PIV)

Particle Image Velocimetry (PIV), a state-of-the-art flow visualization technique, is used in this paper to demonstrate the concept of the Bernoulli equation which is one the oldest and most widely used equations in fluid mechanics. The experiment is based on the venturi effect to permit application of the Bernoulli equation to a laboratory scale test facility. The experimental set-up consists of a horizontal, straight transparent pipe with a venturi tube (contraction and expansion of the pipe diameter). Both water and air pipe flows are characterized. Students are required to measure and predict the average velocities and pressure upstream and downstream of the expansion region, using combined Bernoulli and Continuity equations. The averaged velocities are obtained using a flowmeter and compared with their corresponding two dimensional velocity distribution measured by the PIV system. Pressure difference over the expansion is measured using wall mounted static pressure taps and compared with predicted quantities. The paper includes the cost of the experimental setup and various teaching strategies.Copyright

Teaching of Multimode Heat Transfer Through Laboratory Experiments

Hands-on laboratory skills play a vital role in providing mechanical engineering students with a sound understanding of the scientific fundamentals and their application in solving real-life engineering problems. This paper describes a hands-on laboratory thermofluid project which is taught as part of a one-semester, junior-level mechanical engineering course titled Core Measurements Laboratory. The experiment focuses on characterization of heat transfer from a cartridge-heated, isothermal cylinder inside a circular enclosure, by conduction, natural convection and radiation. The project consists in the design and fabrication of the test facility, data acquisition and comparison of experimental results with analytical predictions, with a formal report submitted on completion. The project is undertaken by a team of four students over a five-week period. Emphasis is placed on highlighting potential discrepancies between measurement and analytical predictions, which are inherent in the test configuration considered, reflecting realistic engineering situations. Sample measurement and analysis results are reported. The teaching strategy employed to integrate fundamental theories with hands-on experiences is described. The effectiveness of the laboratory project in enhancing student learning of heat transfer, engineering analysis of discrepancies between predictions and measurements, and project management skills was demonstrated by monitoring student performance improvements over the duration of the project.© 2010 ASME

Enhancing the Learning of Two-Phase Flow Measurement Techniques in a Modern Mechanical Engineering Program

This paper outlines a proposed low-cost experimental setup for the measurement of two-phase liquid-gas flows in a vertical column. The objective of the test facility is to familiarize students with the challenges in applying measurement techniques to characterize such flows. The test facility incorporates two complementary intrusive and non-intrusive measurement techniques for detecting and studying the dynamics of air bubbles transported in water. The intrusive measurement method uses conductivity probes, while the non-intrusive technique is laser based. For both measurement techniques, details of the data acquisition system and the characteristics of sensors employed are presented. In addition, the teaching strategy is discussed for implementing the use of the proposed two-phase flow experimental setup in a Mechanical Engineering curriculum.Copyright

Innovative Thermofluids Experiments for Modern Mechanical Engineering Education

One of the primary objectives of the Petroleum Institute (PI) is to prepare future mechanical engineers to assume successful career paths in the oil and gas industry. Hands-on laboratory skills play a vital role in providing students with a sound understanding of the scientific fundamentals and their application in solving real-life engineering problems. The Institute’s undergraduate mechanical engineering curriculum incorporates a one-semester junior level course titled Core Measurements, which is taught in a state-of-the-art measurement laboratory. This course includes two innovative hands-on experiments related to experimental heat transfer and fluid dynamics, with the objective of familiarizing the students, through simple projects, with the characterization of fundamental thermofluid phenomena. Each hands-on project consists of design, fabrication, data acquisition and validation of a simple experiment, with a formal report submitted on completion. Each project is undertaken by groups of four students over a five-week period. The first experiment characterizes conductive heat spread within a heat-source-substrate assembly representative of electronics cooling applications. The effects of heat source foot print, substrate geometry and thermal conductivity, and convective cooling conditions are investigated. The temperature distribution on the source and substrate surfaces are measured using thermocouples and infrared thermography, with substrate thermal resistance calculated and compared with analytical solutions. The second experiment aims to enhance student’s learning of internal pipe flows. Single phase flows in a pipe network are characterized for different flow regimes. The pipe network consists of different diameter lines with valves for regulating and directing the flow to make up various series and parallel piping combinations. The relation between head loss due to fluid friction and velocity, pressure drop empirical laws, valve characteristics, and loss coefficient of fittings are investigated using various pressure and flow measuring techniques, including laser Doppler velocimetry (LDV). The paper documents the experiments and the teaching strategy employed to integrate fundamental theories with hands-on experiences. Sample measurement and analysis results are reported. The effectiveness of the proposed experiments in enhancing student learning of thermofluids, engineering analysis of discrepancies between predictions and measurements, and project management skills is highlighted.Copyright

Enhancing the Learning of Surface Wave Dynamics in a Modern Mechanical Engineering Program

This paper outlines a proposed low-cost experimental setup for characterization of surface waves that was designed and fabricated in conjunction with a senior design project. The proposed experimental setup will enhance the student’s learning of surface waves at water-air interface inside an open transparent channel. The experimental study is based on the flow visualization of water waves combined with measurement of water level using a conductance wave height probe. The detail of the data acquisition system and the characteristics of the wave probes are presented. Finally a teaching strategy for implementing the water wave experimental setup in a Mechanical Engineering curriculum is discussed.Copyright

Introducing Temperature Measurement and Control Techniques to Engineering Undergraduate Students in the Gulf Region

Hands-on laboratory skills play a vital role in providing students with a sound understanding of the scientific fundamentals and their application in solving real-life engineering problems. One of the essential laboratory based courses taught at our Institute is Introduction to Measurements and Instrumentation. The design and implementation of such a course has been well documented in Western engineering education, but presents specific challenges in the Gulf region due to economical, social and cultural factors. This paper discusses the adaptation of corresponding Western courses to undergraduate mechanical engineering studies in the Gulf region. Laboratory exercises for temperature measurement and control are described, which consist of four modules, each building upon the other. In each module, students learn how to design an accurate measuring system, and process and interpret collected data. In the first module, the students are required to build a thermocouple reader using an AD620 instrumentation amplifier and to compare measurements with NIST reference tables. The second module is an introduction to LabVIEW, a graphical data acquisition programming language. The students are required to write a LabVIEW program to record multiple thermocouple signals from a heated plate under varying convective cooling conditions, using a high resolution temperature logger with on-board signal conditioning. The third and fourth modules focus on temperature control techniques. In the third laboratory exercise, the students are required to construct an electrical circuit using a low-power PCB relay and NPN bipolar transistor to develop a bang-bang linear temperature controller. The program created in module two is modified to have the heater operation automatically controlled for a fixed temperature set point. In module four, the students replace the bang-bang controller built in the previous lab with a commercially available PID controller and explore the differences between PID and linear temperature control systems. For each module, students are required to submit a formal report covering the theoretical background, the experimental procedure employed, uncertainty analysis, and conclusions and recommendations. An effective teaching strategy is outlined that covers the fundamental concepts of temperature measurement and control through carefully designed experiments, with sample results presented. Emphasis is placed on the tailoring of the course topics to engineering education in the Gulf region.Copyright