Large Engineering Applications Research Articles

Overlaps between industrial informatics and control, data acquisition and management in Big Science

Big Science applications require very large infrastructures and often involve different countries in order to achieve important scientific results or to find solutions to the major problems of mankind, such as finding a clean and endless source of energy. Big Science applications represent not only a scientific challenge, but also large engineering applications involving a wide range of technologies shared with other industrial applications. As a consequence there is a significant overlap in technologies and approaches between Big Science and Industry. In this paper, the overlap between Big Science and industrial applications will be presented in more detail under the control perspective, that is, by highlighting the common aspects between industrial informatics and the control, data acquisition and data management in large scientific applications.

Optical investigation and thermodynamic analysis of premixed ammonia dual-fuel combustion initiated by dodecane pilot fuel

In view of reducing greenhouse gas emissions the transition from fossils fuels to sustainable energy carriers is a prerequisite to keep global warming within tolerable limits. Since IC engines will continue to play a role in global energy strategies during a transitional phase, especially for large engine applications difficult to electrify, the use of ammonia as substitute fuel may be an approach for decarbonization. However, its utilization needs research since ignition concepts and combustion properties still pose considerable challenges in view of reliable and efficient operation. A new "optical engine" test facility ("Flex-OeCoS") has been successfully adapted enabling dodecane pilot fuel ignited premixed ammonia dual-fuel combustion investigations. It features IC engine relevant operation conditions such as pressures, temperatures, and flow (turbulence) conditions as well as adjustable mixture charge composition and pilot fuel injection settings. In parallel, thermodynamic heat release analysis in terms of ignition and combustion characteristics was performed. Simultaneously applied high-speed Schlieren/OH* chemiluminescence measurements supported the examination of the combustion process. Initially premixed ammonia dual fuel combustion has been compared to a representative methane combustion process in terms of different gas properties (lower heating value, air-fuel ratio) which illustrates its lower reactivity affecting heat release and flame propagation. Moreover, ignition delay, combustion transition, and turbulent flame propagation as well as heat release characteristics have been investigated for premixed ammonia dual-fuel combustion within variation of air-fuel equivalence ratio, start of pilot fuel injection, and pressure/temperature operation conditions. The results illustrate strong dependency on air-fuel equivalence ratio (energy content) and temperature conditions in terms of ignition delay, dual-fuel combustion transition, and corresponding heat release. The optical investigations confirm the thermodynamic analysis and promote assessment of pilot fuel evaporation, ignition, combustion transition, and flame propagation. Conclusions give extended insight into the thermo-chemical processes of ammonia pilot fuel ignited dual-fuel combustion. The acquired data may also support further development of numerical CRFD methods.

A high-order discontinuous Galerkin solver for the incompressible RANS equations coupled to the [formula omitted] turbulence model

Accurate methods to solve the Reynolds-Averaged Navier-Stokes (RANS) equations coupled to turbulence models are still of great interest, as this is often the only computationally feasible approach to simulate complex turbulent flows in large engineering applications. In this work, we present a novel discontinuous Galerkin (DG) solver for the RANS equations coupled to the k−ϵ model (in logarithmic form, to ensure positivity of the turbulence quantities). We investigate the possibility of modeling walls with a wall function approach in combination with DG. The solver features an algebraic pressure correction scheme to solve the coupled RANS system, implicit backward differentiation formulae for time discretization, and adopts the Symmetric Interior Penalty method and the Lax-Friedrichs flux to discretize diffusive and convective terms respectively. We pay special attention to the choice of polynomial order for any transported scalar quantity and show it has to be the same as the pressure order to avoid numerical instability. A manufactured solution is used to verify that the solution converges with the expected order of accuracy in space and time. We then simulate a stationary flow over a backward-facing step and a Von Kármán vortex street in the wake of a square cylinder to validate our approach.

Could High H98-Factor Commercial Tokamak Power Plants Use Nb–Ti Toroidal Field Coils?

In large engineering applications, materials that can fail by brittle fracture are avoided if there are practical, ductile alternatives. In recent years, advances in the experimental control and shaping of fusion energy plasmas have produced confinement times that are longer than the accepted IPB98(y,2) values (i.e., higher H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> -factors). Detailed understanding of these enhancements in H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> -factor is not available, but values as large as 1.5-1.8 may be possible. If such high values are reliably realized, they will enable such a large reduction in the magnetic field required from the toroidal field (TF) coils that ductile Nb-Ti becomes a possible superconducting materials choice for TF fusion energy magnets. In this paper, we investigate what values of enhanced H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> -factor are required to enable the commercial use of Nb-Ti TF coils in tokamaks. We have investigated the use of Nb-Ti TF coils in an ITER-like geometry, for a 500 MW net electricity producing tokamak using the PROCESS systems code. If we use present day Nb-Ti conductors, the minimum H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> -factor required for practical power plants is 1.5. For Nb-Ti cable with a critical current density increased by a factor of 5, the minimum falls to H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> ≈ 1.4. With this improvement for an H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">98</sub> = 1.5, aspect ratio 3.1 (i.e., ITER-like geometry) tokamak, we find the cost of base-load electricity is ~42% greater than if Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn is used and about 1.4 times that of a typical fission power strike price (scaled up to 2.5 GWe net electricity).

A Multiple Vibration Modes Separation Technique Based on 3*5 Element Energy Harvester Array: Frequency, Bandwidth Adjustment, and Electrical Characterization

A neat 3*5 element energy harvester array exploiting multiple vibration modes separation technique, has been designed, fabricated, and characterized. A considerable wideband of 15.6 Hz at simulation and 13 Hz at experiment has been gained in a very low frequency range (below 50 Hz), with the acceleration of 1g. Experimental results show that the adjusted harvester could generate the output power of about 2.1 mW at an 8 Hz resonant frequency with the optimum load resistance 350 $\text{k}\Omega $ . Meanwhile, the half-power (1.05 mW) bandwidth could reach up to 15.3 Hz. These results enable the designed device to improve viability for power supply of low power micro electron devices in some special low frequency vibration environment, such as large engineering applications, bridge monitoring, and wildlife monitoring.

Monodisperse non-Newtonian micro-droplet generation in a co-flow device

Monodisperse droplet generation in microfluidic devices has large engineering applications such as in drug encapsulation and food industry. Monodispersity of the droplets in a microdevice is of engineering interest. Non-Newtonian fluids also have a wide range of applications in microfluidic devices whose monodispersity in droplet generation devices has not been studied thoroughly yet. This is an important feature in several applications such as in lab on a chip, food processing, and pharmaceutical applications. In the present study, non-Newtonian droplet generation in a co-flow device is investigated numerically. Xanthan gum solutions and water are used as the dispersed phase fluid. The simulations are performed with considering the effect of dispersed phase viscosity and continuous phase velocity on the droplet formation process. It was found that monodispersity can be achieved when non-Newtonian fluids are used as the dispersed phase in a co-flow device. The effect of varying different parameters on establishing monodispersity was investigated. The results showed that in the jetting regime, the volumes of the droplets are less dependent on the viscosity of the dispersed phase, and the flow rate of the continuous phase has a more significant effect on droplets.