bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coherent Structures of Tornado-Like Vortices
Authors: Karami Mohammad , Carassale Luigi , Hangan Horia , Refan Maryam 
Published: October 2018

Tornado-like vortices have distinctive characteristics that make them significantly different from atmospheric boundary flows. These dynamic characteristics are highly turbulent and unsteady which make them very complex. In this paper, it is tried to identify these dominant patterns, known as coherent structures, out of tornado-like vortex. These vortices are experimentally simulated in a 1/11 scaled model of WindEEE Dome at Western University.
Coherent structures provide simplified but physical understanding of the flow. The classical method for extraction of coherent structures is proper orthogonal decomposition (POD) method. However, there are serious concerns about POD as it has orthogonality constraint. Thus, we applied another method called independent component analysis (ICA) which does not have orthogonality restrictions. This method helped us to identify non-physical POD modes and to provide a better physical description of the flow.
Development of a Measurement Method for the Classification and Performance Evaluation of Positive Pressure Ventilation (PPV) Fans
Authors: Fritsche Manuel , Epple Philipp , Delgado Antonio 
Published: October 2018

Positive Pressure Ventilation (PPV) fans are used by fire departments. The specified performance data differ depending on the manufacturer, as there is no international and commonly accepted standardized measuring method for evaluating the PPV fan performance.
In the present work a new measurement method for the classification and performance evaluation of PPV fans is proposed. These fundamental investigations are based on numerical simulations and experimental test studies. The simulations have been performed with the commercial CFD software ANSYS CFX and the test measurements have been carried out on a newly developed test rig. For the predesign of the measurement method, the flow behavior of a free jet with swirl has been investigated with CFD simulations. A special feature of the PPV fans is that the generated flow rate is not only due to the flow through the rotating impeller, but also a significant flow rate is generated outside the PPV fan due to the viscous shear stresses (principle of a viscous jet pump).
For the measurements a new test rig has been designed in order to measure the flow velocity of the PPV fan as it is in real firefighter’s fire combat situations. The new test rig design concept and the numerical and experimental results of these studies are presented in detail in this work.
Utilization of Churn Flow Coalescer for Improving Foam Breakup in Gas-Liquid Cylinderical Cyclone
Authors: Dabirian Ramin , Gavrielatos Ilias , Mohan Ram S. , Shoham Ovadia 
Published: October 2018

Foaming can hinder gas-liquid separation, therefore, it is desirable to break the foam upstream of separation facilities. There are different methods to breakup foam, including chemical (utilizing defoaming agent), mechanical (such as cyclones), and thermal (by increasing temperature).
Foam stability and breakup are studied in a standalone Churn Flow Coalescer (CFC) and in a Churn Flow Coalescer/Gas-Liquid Cylindrical Cyclone© (CFC/GLCC©) system. The goal is to investigate the possible improvement of the foam breakup efficiency in the GLCC© by installing a CFC upstream of the GLCC©. Testing the standalone CFC, it was found that the CFC generates more, but less stable, foam that can be broken more easily.
Three different CFC’s are tested with diameters of 1″, 2″ and 3″. For the same inlet conditions, the 3″ CFC with tangential inlet was found to be the most efficient for generating less stable foam. The optimal operating conditions for this CFC are at low superficial gas velocities, namely, vsg(CFC) between 0.1 to 0.3 m/s. Higher flow rates generate smaller bubbles and more stable foam. From testing the CFC/GLCC© system, it is found that foam breakup in this system is more efficient than that of the standalone GLCC©, under the same flow conditions.
The operational envelope of the CFC is predicted based on the transition boundary to churn flow developed by Taitel et al. (1980), as a function of the CFC aspect ratio (LE/D). The analysis of transition boundary between slug and churn confirm that less stable foam occurs at the left of churn flow transition boundary.
Calculation of the Maximal Flight Altitude of the Historical HW2 Rocket Using CFD
Authors: Steppert Michael , Epple Philipp , Steber Michael 
Published: October 2018

The historical HW2 rocket was a liquid propulsion rocket, designed by the German rocket pioneer Johannes Winkler in 1932. With this rocket, Winkler tried to reach a much higher altitude than with his first model, the HW1, which was the first liquid propulsion rocket in Europe and reached an altitude of 60 meters. Because of technical problems, the HW2 exploded immediately after the launch on October 6th in 1932 [1] [2].
To estimate the performance of this historical liquid propulsion rocket its maximum flight altitude was computed with the use of CFD. The equation of the vertical flight trajectory was solved numerically, with the classical Runge-Kutta method. For the computation of the vertical trajectory standard atmospheric conditions were considered. To determine the thrust and the drag of the rocket, the Navier-Stokes equations were solved with the commercial CFD solver Star-CCM+ from Siemens PLM Software. The rocket hull and the rocket engine were first simulated independently for different Mach-numbers and atmospheric flight conditions. Finally the complete rocket with running rocket engine was also computed in atmospheric flight conditions. These results were compared with the standalone simulations of the rocket drag without the running rocket engine and with the simulation of the rocket engine alone. The results are shown and analyzed in detail in this work.
Threshold Criteria for Components of Predictive Model for Pipe Flow of Broadly-Graded Slurry
Authors: Matoušek Václav , Visintainer Robert , Furlan John , Sellgren Anders 
Published: October 2018

Industrial slurries transported in pressurized pipelines often consist of particles of broad size distribution. The broad particle size distribution affects slurry flow behavior in a pipe. A four-component model (4CM) predicts the frictional pressure drop in pipe flow of broadly graded slurry. The model considers Newtonian carrying liquid and splits the broadly graded solids into fractions (components) each of which contributes to the pressure drop through its own dominating friction mechanism expressed by a particular sub-model in the 4CM. The sorting of the solids into the components (carrier, pseudo-homogeneous, heterogeneous, fully-stratified) must be based on appropriate criteria. For the sake of simplicity, the 4CM currently uses threshold sizes of particles to split the solids into 4 components.
The goal of the present work is to analyze the existing criteria for the threshold between the pseudo-homogeneous component and heterogeneous component and for the threshold between the heterogeneous component and fully-stratified component. The analysis is based on a description of mechanisms governing particle support (suspension, deposition) of each particular solids component in slurry flow. It shows that the existing grain-size thresholds actually express certain proportions among threshold velocities of flow delimiting different slurry flow regimes. Such threshold velocities are the deposition-limit velocity, the initial-suspension velocity, and the full-suspension velocity. We discuss the proportions and demonstrate how properties (of liquid, solids, flow) and associated parameters additional to the grain size may influence the thresholds.
The analytical results are supported by experimental results for flow of individual components in a laboratory loop.
Construction of a Rain Erosion Test Rig for Wind Energy Blade Coatings
Authors: Mühlbauer Moritz , Thamsen Paul U. , Liersch Jan , Michael Julian , Wagner Maik 
Published: October 2018

Wind turbine blades are constantly exposed to weather conditions, which wear and degrade the surface [1]. Depending on the site of the plant, rain is the main driver for this wear. This rain erosion becomes apparent, when the coating — usually on the leading edge — shows a rough surface or even the bare GFRP looms.
Increased surface roughness usually goes along with diminished performance. This surface erosion occurs mostly near the tips of the blades, where most power is converted. Maintenance teams replace the damaged coatings in costly rope-based operations. To extend maintenance intervals and select the best coating, better understanding of the loads and the non-linear development of erosion damage is necessary.
Therefore a test rig to simulate realistic erosion loads is constructed. The velocity between the surface and the droplet is created by a rotating arm with a vertical axis and a stationary nozzle in one side, similar to the rotating arm apparatus in [2], but much smaller. Our approach is to use relative velocities between droplets and coating which are comparable to the ones seen on wind turbines, as well as a realistic droplet size distribution [3] and ambient pressure.
Rotational speed, temperature, vibrations, flow rate, electric voltage and current are constantly measured to ensure safe operation and repeatable measurements.
Filtration Technology Research of Graphite Dust Produced in Spent Fuel Transportation Process in HTR-PM
Authors: Wang Jinhua , Wang Bing , Wu Bin , Li Yue , Wang Haitao 
Published: October 2018

With the continuous development of the nuclear power technology in the world, all countries in the world are becoming more and more interested in the inherent safety of nuclear power technology, while the research and development of the spherical bed type high temperature gas cooled reactor nuclear power technology in China has formally catered to this demand.
As a major national science and technology project, since the construction of the high temperature gas cooled reactor demonstration project (HTR-PM) since 2012, the civil construction of the nuclear island has been basically completed, the installation of equipment has been carried out orderly, and many process systems have entered debugging and operation stage gradually.
As an important auxiliary process system, fuel handling and storage system for online refueling of the pebble bed high temperature gas cooled reactor, plays an important role in relation to the stable operation of the reactor.
The main functions of the fuel handling and storage system are loading the fresh fuel elements and unloading the spent fuel elements which has reached its target burnup continuously for reactor operation, the spent fuel elements would be discharged into the spent fuel canister firstly, when the spent fuel storage canister is full of spent fuel, the canister would be sealed through welding method, and then the spent fuel canister would be transferred and stored in the spent fuel storage silo with the ground crane system.
The fuel element of the pebble bed high temperature gas cooled reactor is spherical fuel element with graphite matrix, the fuel elements will have friction and collision with the inner wall of the pipeline in transporting process, which will produce graphite dust, the graphite dust should be removed continuously though filtration method, so as not to affect the fuel elements transportation in pipeline.
This article focus on the production mechanism and filtering method of the graphite dust in graphite matrix fuel element transporting process in pipeline, to study the graphite dust removal technology, and then we could provide theoretical guidance for the design and operation of the key system and equipment for HTR-PM.
Numerical Simulation for Nuclear Engineering Education: A Case Study in a Course “Advanced Nuclear Reactor Thermal Analysis”
Authors: Huang Shanfang , Gong Yaopeng , Li Chao , Liu Ruilong , Wang Jiageng , Wang Kan 
Published: October 2018

Nuclear energy is an important way to solve energy shortage and pollution problems today. Therefore, China is vigorously developing nuclear energy and is facing huge demands for talents. However, nuclear engineering education has been severely hampered, particularly in its experiment aspect because of the Fukushima accident. The original sub-critical nuclear reactor at Tsinghua University (THU) was stopped, forcing students to use computers to conduct relevant nuclear simulation experiments.
The emerging of supercomputers and commercial numerical simulation softwares has provided enough hardware and software support for complex calculations required in numerical simulation of nuclear reactors. Thus numerical simulation could be integrated into nuclear engineering education. With its ease of use, quick acquisition and direct visualization of results, numerical simulation can save much time and money. Besides, it is convenient to change simulation conditions which is helpful for academic research and talent development.
This paper starts with THU’s nuclear engineering talent training mode, and taking the course “Advanced Nuclear Reactor Thermal Analysis” as an example, discusses the applications of numerical simulation softwares FLUENT and COBRA-TF in this course. Finally, the analysis shows that numerical simulation performs well in conceptual understanding and experimental design. It plays a significant role in nuclear engineering education, which provides an important reference for the new mode of nuclear engineering education.
Design Study of Beam Window for Accelerator-Driven System With Subcriticality Adjustment Rod
Authors: Sugawara Takanori , Eguchi Yuta , Tsujimoto Kazufumi , Obayashi Hironari , Iwamoto Hiroki , Matsuda Hiroki 
Published: October 2018

Engineering feasibility of the beam window is one of the design issues in the accelerator-driven system (ADS). This study aims to perform the coupled analysis for the feasible beam window concept. To mitigate the design condition, namely to reduce the required proton beam current, subcriticality adjustment rod (SAR) was installed to the ADS core. The burnup analysis was performed for the ADS core with SAR and the results indicated that the maximum proton beam current during the burnup cycle was reduced from 20 to 13.5 mA.
Based on the burnup analysis result, the coupled analysis; particle transport, thermal hydraulics and structural analyses, was performed. As the final result, the following design; the hemisphere shape, the outer radius = 180 mm, the thickness at the top of the beam window = 1.5 mm, and the factor of safety for the buckling = 3.8, was presented. The buckling pressure was almost same as the previous one and more feasible beam window concept was presented through this study.
Interface Tracking Simulations of Two-Phase Flow Utilizing Adaptive Meshing Capabilities
Authors: Cambareri Joseph J. , Bolotnov Igor A. 
Published: October 2018

Due to the increase of computing efficiency and power, full-resolution two-phase flow simulations have become a practical research tool for model development and analysis of reactor flows. The expansion of state-of-the-art high performance computing (HPC) facilities allows for the use of direct numerical simulation (DNS) coupled with Interface Tracking Methods (ITM) to perform full resolution simulations. Given adequate spatial and temporal resolution, DNS can resolve all relevant turbulent scales, allowing for the extraction of high quality and detailed turbulent and two-phase flow numerical data for use in model development. While larger scale bubbly flow DNS are becoming ever more affordable, it is still computationally expensive due to the requirements of the spatial discretization. This presents the largest obstacle for future applications of DNS.
For this reason, mesh adaptation techniques are sought after to reduce the computational expense of bubbly flow simulations in complex geometries. By fully resolving only the areas of specific interest, the computational costs of DNS can be reduced. Grid refinement can be based on the location of the interface between the two phases, area of greatest turbulent intensity, averaged bulk fluid velocity data, or the prediction of bubble movement. Coupled with an advanced bubble tracking algorithm, the path of individual bubbles moving through the computational domain can be predicted, and the computational mesh refined within the path area. This refinement can create tracks of greater resolution for the bubbles to move through in the domain, while keeping the bulk resolution of the mesh coarser. Through these means, the overall cost of the simulation is reduced, while high quality numerical data is still obtainable. This work outlines the enhancement of existing mesh adaptation algorithms to implement the bubble tracking refinement, and its practical applications to full resolution two-phase flow simulations.
Development of Experimental Facility to Study Channel Disassembly Behaviour for Indian PHW Reactor During Heatup
Authors: Sahoo Pradeep K. , Singh Ankit 
Published: October 2018

No experimental investigation has been carried out to understand the progression of channel disassembly in IPHWR. Hence, it is planned to study the deformations aspects through experiments with a scaled-down (1:3) fuel channel of 220MWe reactor. Depending upon the pressure inside the channel and transient past, the accident initiation and disassembly can be can be classified into two class. In the first case, high pressure inside channel leads PT ballooned and fully contacted CT before channel deformed as one composite unit. While in second case, low inside pressure, first leads PT to contact CT and then coupled deformation of the channel progresses. Latter is part of our current experimental investigation.
This paper is focused on discussion about various aspects considered while developing the experimental facility. In this case, experiments are grouped under two broad categories, one is the study under inert environment to check channel deformation due to material flow at higher temperature and other one is under oxidation environment, which would be similar to actual condition exist in normal reactor core under accident scenario. Initially experiments will be carried out on single channels, later it will be extended up to three channels arranged one above other. A simulation study is also carried out to check the deformation profile under inert conditions. Simulation is done using coupled field element technology of commercial software ANSYS v17.2, to get a preliminary insight into structural and thermal coupled response on channel deformation.
Particle Release During Laser Decontamination of Concrete Surfaces
Authors: Kahl Torsten , Greifzu Georg , Herrmann Marion , Lippmann Wolfgang , Hurtado Antonio 
Published: October 2018

The phase–out of all Nuclear Power Plants (NPP) until 2022 in Germany offer the opportunity to apply new and efficient decommissioning technologies, which allow further reduction of decommissioning costs and minimization of the collective dose for personnel. One challenging task in this process is the decontamination of protective paints containing polychlorinated biphenyl (PCB). PCB-containing surfaces demand consecutive radiological decontamination and removal of the PCB-containing paints before the demolition is possible. Laser technology, commonly used in many different industrial sectors, presents an advanced approach to this problem.
Successful thermal decomposition of PCB-containing paints using high power diode lasers has been reported by our group in former publications [1]. Ongoing investigations focus on the technology transfer from static laboratory state to industrial application. This includes the verification of safety and efficiency issues for the complete laser supported process.
The current presentation covers all aspects of the laser process: concrete sample preparation as well as an experimental set-up utilizing a mobile laser system that includes an innovative laser head. Particular focus will be on the phenomena of the generated concrete surfaces and the arising by-products during laser processing.
A 10 kW high power diode laser, Laserline LDF 1500-10000 was used for the ablation experiments. Concrete samples were coated with typical decontamination epoxy-based paints, which match the commonly used paint systems in German NPPs in terms of composition, structure and thickness. The influence of significant processing parameters (laser power, feed rate, type of concrete and composition of paint) on the laser ablation are shown in relation to the energy input per length. The release of particles is subjected to these parameters as well. Therefore the size and the shape of the arising particles have been measured online in accordance with these processing parameters by an Engine Exhaust Particle Sizer (EEPS, Model RP-3090, TSI) in a range between 5.6 to 560 nm. The quantity of particles has also been counted by a Condensation Particle Counter (CPC, Model 3022, TSI). Overall up to 6 million particles per cubic decimeter are detected with a dilution factor of 1:100 throughout the experiments. Both measuring systems are connected to the exhaust air pipe downstream, next to the laser head. The shift of the particle size in accordance with the above mentioned parameters is crucial for a comprehensive understanding of the laser decontamination.
The mobile laser supported decontamination technology will be tested in 2018 in a German nuclear facility. This test will contain the decontamination process with actual surface configurations like floors, walls, ceilings and corners, and will act as an effective proof-of-concept for the developed laser system prototype.
The Design of a Nuclear Emergency Decision Deduction and Training Platform
Authors: Ke Li , Manchun Liang , Guofeng Su , Jie Yang , Jingtao He , Shuijun He 
Published: October 2018

Nuclear accident and nuclear terrorism are of great threats to international security. The countermeasures against nuclear emergency situation should be deliberately considered before it happened. In accordance with experience from Fukushima Daiichi Accident, various kinds of complex situations must be considered at the phase of emergency preparedness. And all related schedules, including national laws and regulations, allocation of responsibility and authority, emergency plans and procedures, facilities, instruments, trainings and exercises must be examined. The appropriateness of the emergency preparedness and the emergency response capability need to be verified through emergency exercises. However, exercises are usually costly and labor-intensive. So, it is necessary to design a software system to help conduct emergency exercises simulation.
A Nuclear Emergency Decision Deduction and Training Platform (NEDDTP) is designed in China Nuclear Security Center of Excellence, which aims at performing the simulation of nuclear emergency process and providing a training platform for emergency workers. 3D models, the environment of nuclear power plant (NPP), some physical numerical models for simulating and several typical nuclear emergency scenarios for training are included in the platform. NEDDTP realizes the function of digitization of scenario, emergency simulation, resource management, command and dispatch, process record and evaluation in exercise, and it also provide VR display for emergency workers.