Towards Fully Additively-Manufactured Permanent Magnet Synchronous Machines: Opportunities and Challenges

With the growing interest in electrification and as hybrid and pure electric powertrains are adopted in more applications, electrical machine design is facing challenges in terms of meeting very demanding performance metrics for example high specific power, harsh environments, etc. This provides clear motivation to explore the impact of advanced materials and manufacturing on the performance of electrical machines. This paper provides an overview of additive manufacturing (AM) approaches that can be used for constructing permanent magnet (PM) machines, with a specific focus on additively-manufactured iron core, winding, insulation, PM as well as cooling systems. Since there has only been a few attempts so far to explore AM in electrical machines (especially when it comes to fully additively-manufactured machines), the benefits and challenges of AM have not been comprehensively understood. In this regard, this paper offers a detailed comparison of multiple multi-material AM methods, showing not only the possibility of fully additively-manufactured PM machines but also the potential significant improvements in their mechanical, electromagnetic and thermal properties. The paper will provide a comprehensive discussion of opportunities and challenges of AM in the context of electrical machines

Investigation of Selective Laser Melting Fabricated Internal Cooling Channels

Channels where coolant is run to cool a system are common in injection mold tooling. Conventionally, these channels are machined into the mold. This has limited the design of mold cooling systems to the constraints of traditional machining processes, where straight circular channels machined from cast material are typical. The transfer of heat away from the part cavity into these cooling channels has a large effect on the cooling time of the injection mold cycle. In this investigation, laser powder bed fusion processes were used to create non-circular cooling channels. To compare cooling performance, elliptical and circular channels of equal crosssectional area were investigated for mass flow rate and rate of heat transfer. Between conventionally machined and additively manufactured channels, surface roughness of the channel wall and condition of the parent material were investigated as potential factors as well. Through simulation, analysis of channel surface roughness, and experimentation, the results indicated that: the channel machined from cast 316L stainless steel had higher flow rate and rate of heat transfer compared to the machined channel fabricated from selective laser melting 316L metal powder, the machined channel had higher flow rate and rate of heat transfer compared to the as-fabricated additively manufactured sample, and the circular additively manufactured channel had higher flow rate and rate of heat transfer compared to the elliptical channel. Overall, the traditionally machined circular channels had superior cooling performance than the additively manufactured elliptical channels. However, the results demonstrate that changing the length-to-width ratio of elliptical cross channels can be used to locally control cooling on regions of the part to reduce hot-spots in the mold and part defects

Shale instability of deviated wellbores in southern Iraqi fields

Wellbore instability problems are the cause for the majority of nonproductive time in the southern Iraqi fields\u27 developments. The most severe problem in terms of effort and disbursement which is referred to a pipe sticking in Tanuma shale formation. Examining the drilling data revealed that this phenomenon was mostly related to the shear failure of the wellbore. Thus, a geomechanical analysis and drilling parameters/ practice optimization analysis were performed on a field in southern Iraq based on data from 45 deviated wells. The geomechanics analysis predicted the suitable drilling fluid density to prevent onset shear failure by using the Mogi-Coulomb failure criterion, including thermally and chemically induced stresses and the bedding related failure of the wellbore. While the drilling parameters optimization was conducted by DROPS simulator and multi-regression analysis and resulted in a significant reduction in the shale exposure time to the drilling fluid. The drilling practice analysis was derived based on drilling data from stuck-free well also facilitated in preventing the drilling fluid density reduction by tripping processes. These analyses identified the following areas of improvement. First, the mud weight being used was not changed properly with respect to variation in wells azimuth and inclination. Secondly, anisotropic effects of the stress and strength parameters for this shale formation should be considered in wells trajectory design. Thirdly, the time depended-failure of wellbore was observed in even though the drilling fluid density was appropriately selected. Fourthly, the swabbing effect while tripping was negatively contributed to wellbore stability. Due to limited of published studies regarding wellbore problems in southern Iraqi fields; this research could serve as a significant case history for similar fields --Abstract, page iii

Liquid Flowmeter Using Thermal Measurement; Design and Application

This thesis presents flowmeter devices which can measure flowrate, pressure and temperature offlowing liquid samples using thermal measurement method. Typical thermal mass flowmeter usesthermal properties of materials to obtain flow features only for gases. We designed and fabricatedflowmeter devices with various functionalities such as: measuring properties of flowing liquid andidentifying the type of liquid samples.Thermal measurement methods using temperature sensor is a key of our flowmeter’s workingprinciple. The thermal mass flowmeter consists of a glass capillary, a tungsten wire heater, and aresistance temperature detector (RTD) sensor. The heater and sensors are integrated on the surface ofthe glass capillary. Noncontact flow measurement between sensor and liquid sample prevents flowdisturbance and corrosion of sensors. When robustness and sensitivity are required for flowmeasurement, the thermal mass time of flight (ToF) measurement method, along with its simplereadout, make it a great candidate for industrial and vehicle applications. The heat traveling timemeasurement is the method that measures the time of flight of thermal mass from heating site tosensing site. Depending on the flowrate of fluid and thermal diffusivity of the liquid sample, the heattraveling time differs.However, low response speed and low sensitivity characteristics are drawbacks of thermalmeasurement methods, which are influenced by thermal properties of materials and structural design.To increase sensitivity of our flowmeter, we fabricated and designed the device using differentcomponent variables such as: size and thickness of RTD sensors, heating element, and glass tubethickness. Also, the flowmeter introduced in this work has two different types based on their size andthey enable large flow range measurement. Micro-flowmeter can measure flowrate less than 100μl/min and macro-flowmeter measures flowrate from 1 to 10 gallon per minute (GPM) of deionized(DI) water.In this work, we used a number of techniques to increase the functionality of our device. Bypasssystem enables to measure high range of flowrate. Also, we designed gravity-driven flowratecalibration system to generate accurate flowrates. Moreover, we developed flowrate monitoringsystem to improve the performance of calibration system

3D Printed Heat Exchangers: An Experimental Study

abstract: As additive manufacturing grows as a cost-effective method of manufacturing, lighter, stronger and more efficient designs emerge. Heat exchangers are one of the most critical thermal devices in the thermal industry. Additive manufacturing brings us a design freedom no other manufacturing technology offers. Advancements in 3D printing lets us reimagine and optimize the performance of the heat exchangers with an incredible design flexibility previously unexplored due to manufacturing constraints. In this research, the additive manufacturing technology and the heat exchanger design are explored to find a unique solution to improve the efficiency of heat exchangers. This includes creating a Triply Periodic Minimal Surface (TPMS) geometry, Schwarz-D in this case, using Mathematica with a flexibility to control the cell size of the models generated. This model is then encased in a closed cubical surface with manifolds for fluid inlets and outlets before 3D printed using the polymer nylon for thermal evaluation. In the extent of this study, the heat exchanger developed is experimentally evaluated. The data obtained are used to derive a relationship between the heat transfer effectiveness and the Number of Transfer Units (NTU).The pressure loss across a fluid channel of the Schwarz D geometry is also studied. The data presented in this study are part of initial experimental evaluation of 3D printed TPMS heat exchangers.Among heat exchangers with similar performance, the Schwarz D geometry is 32% smaller compared to a shell-and-tube heat exchanger.Dissertation/ThesisMasters Thesis Mechanical Engineering 201