A New Approach in the Design of Microstructured Ultralight Components to Achieve Maximum Functional Performance

In the energy and aeronautics industry, some components need to be very light but with high strength. For instance, turbine blades and structural components under rotational centrifugal forces, or internal supports, ask for low weight, and in general, all pieces in energy turbine devices will benefit from weight reductions. In space applications, a high ratio strength/weight is even more important. Light components imply new optimal design concepts, but to be able to be manufactured is the real key enable technology. Additive manufacturing can be an alternative, applying radical new approaches regarding part design and components’ internal structure. Here, a new approach is proposed using the replica of a small structure (cell) in two or three orders of magnitude. Laser Powder Bed Fusion (L-PBF) is one of the most well-known additive manufacturing methods of functional parts (and prototypes as well), for instance, starting from metal powders of heat-resistant alloys. The working conditions for such components demand high mechanical properties at high temperatures, Ni-Co superalloys are a choice. The work here presented proposes the use of “replicative” structures in different sizes and orders of magnitude, to manufacture parts with the minimum weight but achieving the required mechanical properties. Printing process parameters and mechanical performance are analyzed, along with several examples.Thanks are owed to H2020-FETOPEN-2018-2019-2020-01 ADAM2 PROJECT Analysis, Design, And Manufacturing using Microstructures and Authors are grateful to Basque government group IT IT1337-19 and the Ministry of Mineco REF DPI2016-74845-R, PID2019-109340RB-I00, KK-2020/00102, KK-2020/00042 and PID2019-104488RB-I00

Challenges and Status on Design and Computation for Emerging Additive Manufacturing Technologies

The revolution of additive manufacturing (AM) has led to many opportunities in fabricating complex and novel products. The increase of printable materials and the emergence of novel fabrication processes continuously expand the possibility of engineering systems in which product components are no longer limited to be single material, single scale, or single function. In fact, a paradigm shift is taking place in industry from geometry-centered usage to supporting functional demands. Consequently, engineers are expected to resolve a wide range of complex and difficult problems related to functional design. Although a higher degree of design freedom beyond geometry has been enabled by AM, there are only very few computational design approaches in this new AM-enabled domain to design objects with tailored properties and functions. The objectives of this review paper are to provide an overview of recent additive manufacturing developments and current computer-aided design methodologies that can be applied to multimaterial, multiscale, multiform, and multifunctional AM technologies. The difficulties encountered in the computational design approaches are summarized and the future development needs are emphasized. In the paper, some present applications and future trends related to additive manufacturing technologies are also discussed

Chemical and acoustic directed processes for enhancing two-phase porous media fluid flow

This thesis presents a reservoir-on-a-chip study of waterflooding, acoustic streaming and ultrasonic streaming as enhanced oil recovery mechanism. Microfluidic devices with different porosities are fabricated using photolithography or close-packed microbeads to sever as reservoir-on-a-chip micromodels. Optical video fluorescence microscopy is used to track the invasion of a water phase through the oil saturated porous micromodel. In waterflooding study, the degree of water saturation is compared to water containing two different types of chemical modifiers, sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone (PVP), with water in the absence of a surfactant used as a control. Image analysis of our video data yield saturation curves and calculate fractal dimension, which we use to identify how morphology changes the way as invading water phase moves through the porous media. An inverse analysis based on the implicit pressure explicit saturation (IMPES) simulation technique uses mobility ratio as an adjustable parameter to fit our experimental saturation curves. The results from our inverse analysis combined with our image analysis show that this platform can be used to evaluate the effectiveness of surfactants or polymers as additives for enhancing the transport of water through an oil-saturated porous medium. In acoustic streaming study, we also use microparticle image velocimetry to characterize acoustic streaming-induced pumping as a function of frequency and amplitude. A scaling model applied to the velocity distribution is used to construct a state diagram that connects acoustic pressure to filed frequency and amplitude. Based on the measurements of water phase displace oil saturated porous micromodel, we calculate the Black number as a function of frequency to show our system exhibits a narrow band dynamic response consistent with a system operating near resonance. Our observations are compared to a general model for Blake number as a function of frequency, porosity and voltage amplitude that was derived from a force balance model of micromodel undergoing force oscillation. In ultrasonic streaming study, we use particle tracking method to characterize diffusion coefficient and ultrasonic streaming induced as a function of frequency, voltage amplitude and porosity. Brownian dynamics model with ultrasonic streaming force and Hindered diffusion are used to simulation particle diffusion under two parallel wall microfluidic device when ultrasonic wave applies to the system. Based on these measurements, we observe that ultrasonic streaming phenomena appear significantly when amplitude voltage increase or porosity decrease. Besides, porous structure affect resonance frequency for the device. The results from this thesis are broadly applicable to systems beyond enhanced oil recovery, including separations, bio-analytical instrument, additive manufacturing, mixing and flow control

Numerical Simulation of Unconventional Reservoirs Considering Effects of Nanopores Using Reservoir-Scale and Pore-Scale Approaches

Difficulties have been encountered in modelling unconventional reservoirs using traditional approaches. One of the reasons causing the failure is that the mechanisms of fluid flow, phase change etc. in nanopores have not been thoroughly investigated and understood. To study effects of nanopores, in this study, we use both reservoir-scale and pore-scale approaches which could help understand the physics of fluids in nanopores from different levels. At reservoir scale, effects of distribution of nanopores are first studied. To incorporate pore size distribution into reservoir simulation, multi-porosity model is applied to divide shale matrix into different continua based on experimental data. Then phase behavior in different kind of pores is considered by coupling capillary pressure into vapor-liquid equilibrium of the compositional simulator. Besides, production from mixed-wet shale reservoir is studied. Mixed-wettability is modeled explicitly by dividing shale matrix into organic matter and inorganic matter. To construct relative permeability for three-phase flow, interaction between water and oil is simulated by directly performing immiscible displacement on digital rocks; relative permeability of oil and gas is obtained from calculated capillary pressure curve. Then, CO2 injection into shale reservoir is evaluated for both enhanced gas recovery and permeant CO2 sequestration. The dispersed nature of kerogen is characterized and its effects are comprehensively. Critical factors during CO2 injection are evaluated including total organic carbon, injection rate and diffusion coefficient etc. At pore-scale, a pseudo-potential lattice Boltzmann model is extended to study the phase equilibrium in nanopores. The interaction force between molecules in pseudo-potential model is associated with equation of state. The proposed model is validated by comparing equilibrium densities and saturation pressures with predictions from Maxwell construction and equation of state. Simulated interfacial tensions are found consistent with Young-Laplace equation and parachor model. The model is then applied to study the phase change under effects of interface curvature. The deviations of phase equilibrium caused by curved interface curvature is characterized by Kelvin equation. Besides, the length scales of pseudo-potential model for simulating different fluids are determined quantitatively by non-dimensionalizing the interfacial tensions. The length of the lattice spacing in pseudo-potential model is found on the order of a few angstroms due to its interfacial properties