Real Scale Model Research Articles

Integrated wellbore-reservoir modeling based on 3D Navier–Stokes equations with a coupled CFD solver

The occurrence of fluid flow near a wellhead is the major concern of the petroleum industry, as pressure drop, loss of formation, and other variables of interest are mostly affected in this region. The fluid flows from the hydrocarbon reservoir to the wellbore can be characterized as laminar to turbulent; thus, it is important to model this phenomenon with the integrated wellbore-reservoir model. Using 3D Navier–Stokes equations, an integrated wellbore-reservoir model is created in this study, and it incorporates the formation damage zone. For the porous-porous and porous-fluid interfaces, the General Grid Interface (GGI) approach is applied in conjunction with the conservative mass flux interface model. Model equations are solved using a velocity-pressure coupling solver that is pressure-based. For reliable and quick results, the system of equations is solved using an algebraic multigrid approach. The pressure diffusivity equation’s analytical solution under steady-state flow circumstances is used to validate the model. The integrated wellbore-reservoir model is applied to different reservoir scenarios, for example, different production rates, formation zones, and reservoir formation conditions. The results indicate that the present Computational Fluid Dynamics (CFD) model can be extended to simulate the real field scale model. integrated wellbore-reservoir modeling based on 3D Navier–Stokes equations with efficient computational techniques can lead the field of petroleum industries to advance current knowledge.

Electrodynamic Forces in Main Three-Phase Busbar System of Low-Voltage Switchgear—FEA Simulation

This paper concerns the effects of electrodynamic forces that act on current paths that are part of high-grade industrial distribution switchgear. This work is composed of experimental and simulation sections. In the experimental section, the short-circuit tests are presented and the occurrence of electrodynamic forces are shown in a visible way. The formation of electrodynamic forces in the current circuits of electrical energy distribution systems is related to the flow of high currents, but mostly it is related to short-circuit currents. In order to highlight these phenomena, the detailed specification of the parameters during tests is displayed. In the simulation section, the physical phenomenon of electrodynamic forces is being captured by employing a detailed real-scale model of switchgear and current paths. Therefore, the authors proposed employment of the FEM (finite element method) in order to obtain values of electrodynamic forces acting on the current paths by executing the detailed 3D coupled simulation. The analysis of the results and aftermath effects of their interactions provided interesting conclusions that concerned the operation of such power distribution layouts in critical short-circuit conditions.

Evaluation of arched EPS block and geocell inclusions in trench backfill for protection of buried flexible pipes

This paper presents an experimental investigation examining the novel idea of employing curved expanded-Polystyrene (EPS) blocks that arch around the upper section of buried flexible pipes to reduce the pressures acting on them and hence resulting deformation/deflections. Large-scale testing was performed to examine key performance indicators for reinstated trenches with buried 250-mm diameter plastic pipe (0.75-m invert depth) when subjected to cyclic surface loading simulating vehicular traffic. The real-scale model tests investigated unreinforced and geocell-reinforced trenches with conventional rectangular and differently shaped EPS block inclusions placed above the crown or fitting snugly around the upper section of the buried pipes. Compared to conventional rectangular EPS block, the curved-arched EPS block produced greater reductions in the pressures acting on the buried pipes, resulting in substantially smaller pipe deformation/deflections. The geocell layer overlying the EPS block significantly reduced the pressures bearing on the highly compressible EPS material, thereby reducing its compression and the trench surface settlement. Optimum trench reinstatements incorporated both the geocell layer and a 75-mm thick curved-arched EPS block fitted around the top section of the pipe. Doubling the EPS block thickness produced only modest reductions in the pipe deflections, but significantly increased the trench surface settlement.

Reconstructing the Global Stress of Marine Structures Based on Artificial-Intelligence-Generated Content

This paper proposes an approach that utilizes Artificial-Intelligence-Generated Content (AIGC) to overcome the constraints of Structural Health Monitoring (SHM) devices in capturing global stress with limited sensors. Feature elements are selected based on correlation analysis among finite elements and used as stress-measured points. An Artificial Neural Network (ANN) is used to establish the relationship between the feature and correlation elements. The proposed method is applied to the connector structure of an offshore platform, and an optimal ANN is established to optimize its performance by considering factors such as the number of sensors, the neural network framework, and the convergence criteria. The generalization performance of the ANN is validated through a real-scale model test, with deviations below 10% and an average deviation of less than 4% in multiple conditions, verifying its accuracy. This technology represents a significant advancement, enhancing the practicality of the SHM technology from “point monitoring” to “field monitoring”.

Validation of and Simulations using a High-Temperature Electrolysis Model

A continuum mechanistic, real-scale model with the most important reactions of high-temperature electrolysis is proposed. IV-characteristics and impedance spectra serve as comparison to experimental data for steam, CO2 and co-electrolysis. The exchange current-density i0 can be determined to the same order of magnitude as observed in experiments for steam electrolysis. The IV-characteristics for CO2 electrolysis are well described by an i0 one order of magnitude lower as compared to steam electrolysis. Parameter variations identify contributing variables determining the shapes of characteristics. Limitations in prediction are revealed for low current densities up to 0.5 A∙cm-2. EIS calculations demonstrate the dominant behavior of charge transfer or oxygen ion incorporation into the lattice as function of i0 or temperature. The model forms a solid basis for various future investigations like a more detailed reaction system with possible intermediates or degradation and poisoning effects.

Accuracy Assessment of Establishing 3D Real Scale Model in Close-Range Photogrammetry with Digital Camera

Three-dimensional (3D) real scale models delivered from digital photogrammetric techniques have rapidly increased to meet the requirements of many applications in different fields of daily life. This paper deals with the establishment of a 3D real scale model from a block of images (18 images) that were captured by using Canon EOS 500D digital camera to cover a test field area consisting of 90 artificial target points, 25 of them are ground control points (GCPs) while the remains are checkpoints (CPs). The analytical photogrammetric processes including the calculation of interior orientation parameters (IOPs) of the camera during the camera calibration process, exterior orientation parameters (EOPs) of the camera in each capturing, and the object space (ground) coordinates of the model are calculated simultaneously based on collinearity equation using bundle block adjustment method (BBA). Assessment and validation of the accuracy of the results is an important task in this study that was implemented to determine and analyze the errors of 3D coordinates through linear regression analysis (LRA). Root mean square error (RMSE) is the statistical parameter that was used in the statistical analysis of results. The standard error is another statistical parameter which also used to evaluate the accuracy of locations and rotation angles (EOPs) of cameras. The total RMSE (RMSE)xyz of GCPs is ± 2.530 mm while the total RMSE (RMSExyz) of CPs is ± 2.740 mm. The overall accuracy of the work is 5.000 mm.

Heat transfer performance of energy piles in seasonally frozen soil areas

Energy piles constitute a combination of ground source heat pump and building pile foundation technology. Energy piles can not only exchange heat with soil and extract geothermal energy but can also bear upper loads. However, due to the complex geological and climatic conditions in seasonally frozen soil areas, research on the heat transfer performance of energy piles in these areas is limited. According to the characteristics of the ground temperature distribution in seasonally frozen soil areas, the soil region can be divided into frozen and nonfrozen layers. First, a laboratory model test was carried out to investigate the heat transfer performance in these two layers. Then, a three-dimensional heat transfer model of an energy pile suitable for seasonally frozen soil areas was established. The actual working conditions of the real-scale model were simulated, and parametric analysis was then conducted. The results indicated that in annual energy pile operation, the energy pile maximum heat exchange amount per unit length can reach 125 W/m. In the performed parametric analysis, the pile length, concrete thermal conductivity, fluid volumetric flowrate and pipe type impose the greatest influence on the energy pile heat transfer performance, while the pile diameter and concrete cover thickness impose relatively little influence. Moreover, the influence of the pipe diameter should be further studied.

Increase in overtopping rate caused by local gust-winds during the passage of a typhoon

ABSTRACT A field survey of Fukuura Coast (in Tokyo Bay, Japan) revealed during the passage of Typhoon Faxai in 2019 waves with considerable momentum caused significant wave overtopping, resulting in structural damage to coastal defenses and localized flooding. The hindcasted wave height using a third-generation wave model was not high enough to explain the extent of the local damage at Fukuura Coast, likely due to such methods failing to take into account the strong gust-winds recorded during the passage of the typhoon. To solve such problems the authors developed a new numerical model that takes into account the dynamic interaction of air and water, based on the finite volume method (FVM) and the volume of fluid method (VOF). Although this model still slightly underestimates the measurements in the experiments previously conducted by different authors, it is better than existing methods when estimating the overtopping rates under strong winds. The model was then applied to a real-scale model of Fukuura Coast, where by taking into account strong gust-wind speed of 41 m/s the authors were able to explain the phenomena that took place.

Automated Guided Vehicle Control System for Automated Parking Purposes

For the safe transport of the load using automated controlled vehicles, specifically pallets with passenger cars, it is necessary to design a control processes at multiple levels. However, the custom control of such transporters is also very complex because, in addition to the standard control loops of the drives, it is necessary to precisely compare the pallets to the lifting points, in the case of battery power to predict the range, diagnose the components states and other related tasks. This article deals with the real scale model built for parking house purposes and individual parts of the control system and its functional tests.

Numerical Modeling of Mine Hoist Disc Brake Temperature for Safer Operation

The sustainable exploitation of raw materials, with improved safety and increased productivity, is closely linked to the development of mechanical mining installations. Mine hoists are designed for the transport of material, equipment and personnel between the mine surface and the underground. The mine hoist braking system is of paramount importance in its safe operation. Thus, for both drum and disc brake systems, the temperature of the friction surfaces is important for ensuring efficient braking, as exceeding the temperature threshold causes a decrease in the braking capacity. In this paper we present a numerical calculation model for the temperature of the braking disc of a mine hoist in the case of emergency braking. A real-scale model was built, based on the cable drive wheel and disc brake system of a hoisting machine used in Romania. Real material characteristics were imposed for the brake discs, the cable drive wheel and the brake pads. The simulation was performed for decelerations of 3, 3.5, 4 and 4.5 m/s2. The analysis shows that regardless of the acceleration and time simulated, the disc temperature reaches its maximum after 1.35 s of emergency braking. This value does not exceed the 327 °C limit where, according to previous studies, the braking power starts to fade. It means that the emergency braking is safe for the acceleration and masses under consideration, in the case of the studied mine hoist.

Investigation of Rupture in SS304 Steel Sheet using Macroscopic Criteria

Macroscopic ductile rupture prediction in materials always has been great interest in the investigation of rupture. Numerical simulations with finite element codes allow investigating rupture prediction in real scale model. This paper is focused on discussion of procedure for prediction of the rupture in tensile test for a typical SS 304 Stainless Steel sheet. For this procedure, experimentation of tensile test with the conventional Universal Testing Machine (UTM) and Digital Correlation Devices (DIC) are needed to be used. The data obtained from experimentation is used for determining Young’s modulus (E), Rp0.2% and Rm These data further used for simulation upto rupture. The output result obtained from simulation is used in macroscopic ductile fracture criteria which gives damage value to predict onset rupture.

Fire Spread in Insulation Materials in the Ceiling of a Piloti-Type Structure

In piloti-type structures, large-scale fires frequently occur because insulation materials in the ceiling are ignited. However, the spread of fire in these cases is not well known. Therefore, this study conducted small-scale (1.0 m × 1.0 m) tests and real-scale model tests. According to the results, we clarified the fire spread, temperature variation over time, and the effects of insulation materials in fire sites. For the small-scale tests, the internal structure of the ceiling was extruded polystyrene (XPS) + sheet molding compound (SMC), retardant expanded polystyrene (Retardant EPS) + sheet molding compound (SMC), and extruded polystyrene (XPS) + design metal ceiling (DMC). From the small-scale and large-scale tests that simulated a fire in a piloti-type structure, the flow of heat in the interior space and the cause of a large fire were identified. The tests were conducted with EPS+DMC, defined as the best-case scenario, and XPS+SMC, defined as the worst-case scenario during a fire accident. The results from the tests showed that combustion began when the insulation material was exposed to the fire source. Then, molten XPS fell onto the SMC, establishing a new fire source that destroyed the ceiling material, leading to increased combustion due to the inflow of oxygen.

Experimental Wind Characterization with the SuperCam Microphone under a Simulated martian Atmosphere

Located on top of the mast of the Mars 2020 Perseverance rover, the SuperCam instrument suite includes a microphone to record audible sounds from 100Hz to 10kHz on the surface of Mars. It will support SuperCam’s Laser-Induced Breakdown Spectroscopy investigation by recording laser-induced shock-waves but it will also record aeroacoustic noise generated by wind flowing past the microphone. This experimental study was conducted in the Aarhus planetary wind-tunnel under low CO2 pressure with wind generated at several velocities. It focused on understanding the wind-induced acoustic signal measured by microphones instrumented in a real scale model of the rover mast as a function of the wind speed and wind orientation. Acoustic spectra recorded under a wind flow show that the low-frequency range of the microphone signal is mainly influenced by the wind velocity. In contrast, the higher frequency range is seen to depend on the wind direction relative to the microphone. On the one hand, for the wind conditions tested inside the tunnel, it is shown that the Root Mean Square of the pressure, computed over the 100Hz to 500Hz frequency range, is proportional to the dynamic pressure. Therefore, the SuperCam microphone will be able to estimate the wind speed, considering an in situ cross-calibration with the Mars Environmental Dynamic Analyzer. On the other hand, for a given wind speed, it is observed that the root mean square of the pressure, computed over the 500Hz to 2000Hz frequency range, is at its minimum when the microphone is facing the wind whereas it is at its maximum when the microphone is pointing downwind. Hence, a full 360∘ rotation of the mast in azimuth in parallel with sound recording can be used to retrieve the wind direction.We demonstrate that the SuperCam Microphone has a priori the potential to determine both the speed and the direction of the wind on Mars, thus contributing to atmospheric science investigations.

Full Surface Heat Transfer Characteristics of Stator Ventilation Duct of a Turbine Generator

Turbine generators operate with complex cooling systems due to the challenge in controlling the peak temperature of the stator bar caused by Ohm loss, which is unavoidable. Therefore, it is important to characterize and quantify the thermal performance of the cooling system. The focus of the present research is to investigate the heat transfer and pressure loss characteristics of a typical cooling system, the so-called stator ventilation duct. A real scale model was built at its operating conditions for the present study. The direction of cooling air was varied to consider its operation condition, so that there are: (1) outward flow; and (2) inward flow cases. In addition, the effect of (3) cross flow (inward with cross flow case) was also studied. The transient heat transfer method using thermochromic liquid crystals is implemented to measure full surface heat transfer distribution. A series of computational fluid dynamics (CFD) analyses were also conducted to support the observation from the experiment. For the outward flow case, the results suggest that the average Nusselt numbers of the 2nd and 3rd ducts are at maximum 100% and 30% higher, respectively, than the inward flow case. The trend was similar with the effect of cross flow. The CFD results were in good agreement with the experimental data.

Modeling and Simulation of a Thermal and Thermoelectric Generation System in Geothermal Installations

Abstract This paper presents a theoretical simulation and modeling of a new system to generate thermal and thermoelectric energy in building geothermal facilities. The simulation has been developed for a closed loop geothermal circuit based on a new engineering design of multiple heat exchangers and thermoelectric generators (TEG) in both upward and downward section. The paper is based on previous studies and shows the feasibility of supplying thermal energy and electric current to domestic applications especially in cold climates using existing geothermal installations. Carried out tests in small prototypes have proved the validity of the simulation within very high accuracy for the COP coefficient (99%) and slightly lower for thermal and electric energy generated, 96%. The simulation model has been applied to a real scale system showing a predicted COP value very close to the simulation result, within 95% accuracy. The analysis of the real scale model predicts the system can supply thermal energy in excess to a small community and electric energy with a covering factor up to 85% depending on weather temperature. Keywords: Thermal and thermoelectric generation. Building geothermal engineering design. Cite this Article Leticia Bottazzi, Carlos Armenta-Deu. Modeling and Simulation of A Thermal and Thermoelectric Generation System in Geothermal Installations. Journal of Thermal Engineering and Applications . 2020; 7(1): 40–49p.

A Study on the Slope Failure Monitoring of a Model Slope by the Application of a Displacement Sensor

Many causalities and economic losses are caused by natural disasters, such as landslides and slope failures, every year. This suggests that there is a need for an early warning system to mitigate casualties and economic losses. Most of the studies on early warning systems have been carried out by predicting landslide-prone areas, but studies related to the prediction of landslide occurrence time points by the real-time monitoring of slope displacement are still insufficient. In this study, a displacement sensor and an Internet of Things (IoT) monitoring system were combined together, to monitor slope failure through cutting experiments of a real-scale model slope. Real-time monitoring of the slope movement was performed simultaneously via a low-cost, efficient, and easy-to-use IoT system. Based on the obtained displacement data, an inverse displacement analysis was performed. Finally, a slope instrumentation standard was proposed based on the slope of the inverse displacement for early evacuation before slope failure.

Fire Spread of Thermal Insulation Materials in the Ceiling of Piloti-Type Structure: Comparison of Numerical Simulation and Experimental Fire Tests Using Small- and Real-Scale Models

Large-scale fires mainly due to the ignition of thermal insulation materials in the ceiling of piloti-type structures are becoming frequent. However, the fire spread in these cases is not well understood. Herein we performed small-scale and real-scale model tests, and numerical simulations using a fire dynamics simulator (FDS). The experimental and FDS results were compared to elucidate fire spread and effects of thermal insulation materials on it. Comparison of real-scale fire test and FDS results revealed that extruded polystyrene (XPS) thermal insulation material generated additional ignition sources above the ceiling materials upon melting and propagated and sustained the fire. Deformation of these materials during fire test generated gaps, and combustible gases leaked out to cause fire spread. When the ceiling materials collapsed, air flew in through the gaps, leading to flashover that rapidly increased fire intensity and degree of spread. Although the variations of temperatures in real-scale fire test and FDS analysis were approximately similar, melting of XPS and generation of ignition sources could not be reproduced using FDS. Thus, artificial settings that increase the size and intensity of ignition sources at the appropriate moment in FDS were needed to achieve results comparable to those recorded by heat detectors in real-scale fire tests.

Active Separation Control at the Pylon-Wing Junction of a Real-Scale Model

The effect of active flow control on local flow separation behind the installation location of an ultra-high-bypass-ratio nacelle is investigated in a real-scale experiment at the TsAGI T-101 wind tunnel. The investigated model represents a swept 2.5D section of the pylon-wing junction in landing configuration. A flow control system employing periodic excitation is integrated into the unprotected leading edge inboard of the pylon. Tuft visualization as well as pressure and force measurements are used to investigate the vortex-dominated base flow and the effect of active flow control. It is shown that the flow control effect is governed by the normalized parameters of flow control, the momentum coefficient, and the velocity ratio, and is largely independent of the free-stream Mach and Reynolds number within the investigated range. The influence of a variation of the momentum coefficient on the lift gain is investigated. At the highest Reynolds number of an application of active flow control with fully eliminates local separation and increases total lift by approximately 2% of the respective baseline value across a range of 5 deg in angle of attack.

A Study on Evacuation Safety at Inundated Stairs by using Real-scale Hydraulic Model Experiment

In recent years, sudden and local downpours in Korea have become more frequent. These rainfall patterns increase load on drainage system and reduce ability to exclude inland water, leading to flooding. If such rainfall patterns lead to flash floods especially in dense urban areas, sudden submergence of underground spaces by floods can be a fatal threat to life. Therefore, it is very important to secure evacuation routes in case of inundated underground spaces. In this study, we tried to determine evacuation safety by understanding hydraulic characteristics of inundated stairs that could become evacuation routes in underground spaces. For this purpose, water depth and volume flow rate were measured at each point of inundated stairs, and data obtained from results were used to evaluate evacuation safety at each step.

Fire modeling in a nonventilated corridor

The main objective of this study was to determine the effect of fire in a nonventilated corridor. A real-scale model of a corridor has been modeled in Fire Dynamics Simulator(F.D.S.) in order to determine the evolution of indoor temperatures, the visibility and the oxygen quantities during a fire. The start time of a sprinkler has also been determined. The use of sprinklers in buildings has become a necessity and a requirement imposed by technical norms. The provision of this type of installation has become a common feature in buildings with a high fire risk, with two main effects: fire extinction and protection of structural and partition elements from high temperatures[15]. The ultimate goal is to ensure optimal conditions for saving the building users, intervention teams and maintaining the stability of the building. Low temperatures and good visibility on the escape routes during a fire are the basic conditions to ensure the optimal evacuation of users.