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A pre-protection method for a pipe-jacking channel over shield tunnels

Yunliang Cui Xukun Yang Xinquan Wang Hongguo Diao Xiao Li Yuanyuan Gao
Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | 72 | 2 | e148443 | DOI: 10.24425/bpasts.2023.148443
Keywords shield pipe jacking numerical simulation
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Abstract

With the improvement of the planning level of underground space, the location of the planned under-crossing tunnel can be known in advance when constructing the upper-span tunnel. Therefore, pre-protection measures can be taken in advance during the construction of the upper-span tunnel. A new pre-protection method of a pipe-jacking channel was proposed to reduce the adverse effects of under-crossing shield tunnels. Numerical simulations of different pre-protection schemes were carried out using the finite element method to analyze its deformation control effect. The simulation results show that the deformation control effect of the gantry reinforcement scheme is the most significant. It is shown that the displacement of the pipe-jacking channel is more significantly suppressed with pre-protection measures than without preventive protection measures. The vertical displacement curve of the pipe-jacking channel exhibits a “W” shape after the construction of the double-lane shield underpass. By comparing the three different working conditions, it is found that the maximum vertical displacement and surface settlement of the pipe-jacking channel greatly reduced the gantry reinforcement pre-protection. Compared with Case 3, the effect of the pre-protection measures adopted in Case 2 was less obvious, which indicated that the form of the pre-protection had an important influence on controlling the deformation of the pipe-jacking channel.
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Authors and Affiliations

Yunliang Cui
1 2
Xukun Yang
1 2
ORCID: ORCID
Xinquan Wang
1 2
Hongguo Diao
1 2
Xiao Li
1 2
Yuanyuan Gao
1 2
  1. School of Engineering, Hangzhou City University, Hangzhou 310015, PR China
  2. Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province, Hangzhou 310015, PR China

Numerical Evaluation of the Impact of Riser Geometry on The Shrinkage Defects Formation in the Solidifying Casting

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 1 | 181-187 | DOI: 10.24425/amm.2022.137487
Keywords numerical simulations solidification casting defects FEM
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Abstract

The work concerns of modeling the process of manufacturing machine parts by casting method. Making a casting without internal defects is a difficult task and usually requires numerous computer simulations and their experimental verification at the prototyping stage. Numerical simulations are then of priority importance in determining the appropriate parameters of the casting process and in selecting the shape of the riser for the casting fed with it. These actions are aimed at leading shrinkage defects to the riser, so that the casting remains free from this type of defects. Since shrinkage defects usually disqualify the casting from its further use, this type of research is still valid and requires further work. The paper presents the mathematical model and the results of numerical simulations of the casting solidification process obtained by using the Finite Element Method (FEM). A partial differential equation describing the course of thermal phenomena in the process of 3D casting creating was applied. This equation was supplemented with appropriate boundary and initial conditions that define the physical problem under consideration. In numerical simulations, by selecting the appropriate shape riser, an attempt was made to obtain a casting without internal defects, using a simple method of identifying their location. This is the main aim of the research as such defects in the casting disqualify it from use.
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Authors and Affiliations

L. Sowa
1
ORCID: ORCID
T. Skrzypczak
1
ORCID: ORCID
P. Kwiatoń
1
ORCID: ORCID
  1. Czestochowa University of Technology, Department of Mechanics and Machine Design Fundamentals, Dąbrowskiego 73, 42-200 Częstochowa, Poland

Influence of Liquid Metal Movements on the Casting Creation

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Metallurgy and Materials | 2021 | vol. 66 | No 2 | 489-495 | DOI: 10.24425/amm.2021.135883
Keywords numerical simulations solidification Navier-Stokes equations
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Abstract

Knowledge about complex physical phenomena used in the casting process simulation requires continuous complementary research and improvement in mathematical modeling. The basic mathematical model taking into account only thermal phenomena often becomes insufficient to analyze the process of metal solidification, therefore more complex models are formulated, which include coupled heat-flow phenomena, mechanical or shrinkage phenomena. However, such models significantly complicate and lengthen numerical simulations; therefore the work is limited only to the analysis of coupled thermal and flow phenomena. The mathematical description consists then of a system of Navier-Stokes differential equations, flow continuity and energy. The finite element method was used to numerically modeling this problem. In computer simulations, the impact of liquid metal movements on the alloy solidification process in the casting-riser system was assessed, which was the purpose of this work, and the locations of possible shrinkage defects were pointed out, trying to ensure the right supply conditions for the casting to be free from these defects.
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Authors and Affiliations

L. Sowa
1
ORCID: ORCID
T. Skrzypczak
1
ORCID: ORCID
P. Kwiatoń
1
ORCID: ORCID
  1. Czestochowa University of Technology, Department of Mechanics and Machine Design Fundamentals, 73 Dąbrowskiego Str., 42-200 Częstochowa, Poland

Analysis of the inadequacy of determining the spectral characteristics of optical fibre periodic structures by way of numerical modelling

Piotr Stępniak Piotr Kisała
Metrology and Measurement Systems | 2020 | vol. 27 | No 1 | 33-50 | DOI: 10.24425/mms.2020.131713
Keywords numerical simulations fibre Bragg grating numerical modelling
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Abstract

As part of the work, the error level of simulations of uniform optical-fibre Bragg gratings was determined using the transitionmatrixmethod. The errorswere established by comparing the transmission characteristics of the structures obtained by simulation with the corresponding characteristics arrived at experimentally. To compile these objects, elementary properties of the characteristics were specified, also affecting the applications of Bragg gratings, and compared with each other. The level of error in determining each of these features was estimated. Relationships were also found between the size of the physical properties of Bragg gratings and the level of errors obtained. Based on the findings, the correctness of the simulation of structures with the said method was verified, giving satisfying results.

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Authors and Affiliations

Piotr Stępniak
Piotr Kisała

High performance optical shutter design with scalable aperture

Piotr Pokryszka Mateusz Wośko Wojciech Kijaszek Regina Paszkiewicz
Bulletin of the Polish Academy of Sciences Technical Sciences | 2021 | 69 | 5 | e138236 | DOI: 10.24425/bpasts.2021.138236
Keywords optical shutter numerical simulation current source jitter
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Abstract

In this paper, design, construction and switching parameters of a self-made optical shutter with scalable aperture were reported. The aim of the study was to obtain the shortest possible switching times, minimum shutter open time and comparable with commercial shutter, the switch-on and switch-off times. For this purpose, numerical simulations were performed using Comsol Multiphysics 5.4. The design of the shutter and the control system have been optimized accordingly to the obtained results of numerical simulations. The optimized design was fabricated in a professional mechanical workshop and operational parameters of the constructed device were investigated. The switching parameters of the shutter, such as opening time, closing time, minimum shutter open time and other parameters were measured. The values of the parameters were determined from a statistical analysis of a sample consisting of 10,000 measurement results. The performed characterization showed that the tested device has the opening time of 0.8 ms, while the closing time is approximately 1 ms. The designed device is characterized by the minimum shutter open time of 6.4 ms.
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Bibliography

  1.  H. Jo and D. Kim, “Observations of in vivo laser tissue ablation in animal models with different chromophores on the skin and modulating duration per laser exposure,” Lasers Med. Sci., vol. 34, no. 5, pp. 1031–1039, 2019.
  2.  T. Osuch, P. Gąsior, K. Markowski, and K. Jędrzejewski, “Development of fiber bragg gratings technology and their complex structures for sensing, telecommunications and microwave photonics applications,” Bull. Pol. Acad. Sci. Tech. Sci., vol. 62, no. 4, pp. 627–633, 2014.
  3.  W. Lamperska, J. Masajada, S. Drobczyński, and P. Gusin, “Two-laser optical tweezers with a blinking beam,” Opt. Lasers Eng., vol. 94, pp. 82–89, 2017.
  4.  H. Kim, W.-K. Lee, D.-H. Yu, M.-S. Heo, C. Park, S. Lee, and Y. Lee, “Atom shutter using bender piezoactuator,” Rev. Sci. Instrum., vol. 88, no. 2, 2017.
  5.  C. Colquhoun, A. Di Carli, S. Kuhr, and E. Haller, “Note: A simple laser shutter with protective shielding for beam powers up to 1 w,” Rev. Sci. Instrum., vol. 89, no. 12, 2018.
  6.  Thorlabs, “Optical shutters,” https://www.thorlabs.com/ newgrouppage9.cfm?objectgroup_id=927, (Accessed on 20/02/2021).
  7.  K. Singer, S. Jochim, M. Mudrich, A. Mosk, and M. Weidemüller, “Low-cost mechanical shutter for light beams,” Rev. Sci. Instrum., vol. 73, no. 12, pp. 4402–4404, 2002.
  8.  L.P. Maguire, S. Szilagyi, and R. E. Scholten, “High performance laser shutter using a hard disk drive voice-coil actuator,” Rev. Sci. Instrum., vol. 75, no. 9, pp. 3077–3079, 2004.
  9.  W. Bowden, I.R. Hill, P.E.G. Baird, and P. Gill, “Note: A highperformance, low-cost laser shutter using a piezoelectric cantilever actuator,” Rev. Sci. Instrum., vol. 88, no. 1, p. 016102, 2017.
  10.  P.-W. Huang, B. Tang, Z.-Y. Xiong, J.-Q. Zhong, J. Wang, and M.-S. Zhan, “Note: A compact low-vibration high-performance optical shutter for precision measurement experiments,” Rev. Sci. Instrum., vol. 89, no. 9, 2018.
  11.  G.H. Zhang, B. Braverman, A. Kawasaki, and V. Vuletić, “Note: Fast compact laser shutter using a direct current motor and threedimensional printing,” Rev. Sci. Instrum., vol. 86, no. 12, p. 126105, 2015.
  12.  S. Martínez, L. Hernández, D. Reyes, E. Gomez, M. Ivory, C Davison, and S. Aubin, “Note: Fast, small, and low vibration mechanical laser shutters,” Rev. Sci. Instrum., vol. 82, no. 4, p. 046102, 2011.
  13.  Newport, “Electronic fast shutters,” https://www.newport.com/f/electronic-fast-shutters, (Accessed on 20/02/2021).
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Authors and Affiliations

Piotr Pokryszka
1
ORCID: ORCID
Mateusz Wośko
1
ORCID: ORCID
Wojciech Kijaszek
1
ORCID: ORCID
Regina Paszkiewicz
1
ORCID: ORCID
  1. Wrocław University of Science and Technology, wybrzeze Stanislawa Wyspianskiego 27, 50-370 Wroclaw, Poland

Vibrations of the non-linear three-body wheeled vehicle model. Bifukatoins and chaotic

Ryszard Andrzejewski Jerzy Werner
Archive of Mechanical Engineering | 2002 | vol. 49 | No 1 | 81-95
Keywords vibrations bifurkation numerical simulation vehicle suspension
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Abstract

The paper presents theoretical analysis of excited vibrations of the vehicle in a wide range of excitation frequencies (from I to 80 Hz). The mathematical model and calculations were prepared for the accepted physical model of the vehicle. The model was used to simulate the excited vertical vibrations. The bifurcation figures with an excitation frequency as a bifurcation parameter were determined on the basis of the simulation results - the changes of kinematics values in time. Bifurcation diagrams give a picture of vehicle vibrations. This picture gives the possibility of identification of characteristic parameters of sprigs and dumping elements and can be used for control, diagnostic aims, and for making technical investigations of vehicle suspension.
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Authors and Affiliations

Ryszard Andrzejewski
Jerzy Werner

Numerical Simulation of the Influencing Factors of Array Jet Shock Cooling

Nianyong Zhou Youxin Zhou Yingjie Zhao Qingguo Bao Guanghua Tang Wenyu Lv
Bulletin of the Polish Academy of Sciences Technical Sciences | 2024 | e150200 | DOI: 10.24425/bpasts.2024.150200
Keywords array jet enhanced heat exchange numerical simulation
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Abstract

Array jet impingement cooling is a significant technology of enhanced heat dissipation which is fit for high heat flux flow with large area. It is gradually applied to the cooling of electronic devices. However, The researches on the nozzle array mode and the uniformity of cooling surface still have deficiencies. Therefore, the influence of heat flux, inlet temperature, jet height, array mode and diversion structure on jet impingement cooling performance and temperature distribution uniformity is analyzed by means of numerical calculation. The results show that the heat transfer coefficient of jet impingement cooling increases linearly with the increment of heat flux and inlet temperature. With the increment of the ratio of jet height to nozzle diameter (H/d), the heat transfer coefficient increases first and then decreases, that is, there is an optimal H/d, which makes the heat transfer performance of the array jet impact cooling best. The temperature uniformity of array jet impact cooling is greatly affected by array mode. The improvement effect of nozzle array mode on temperature uniformity is ranked as sequential > staggered > shield > elliptical array. The overall temperature uniformity and heat transfer coefficient are increased by 5.88% and 7.29% compared with elliptical array. The heat transfer performance can be further improved by adding a flow channel to the in-line array layout, in which the heat transfer coefficient is increased by 6.53% and the overall temperature uniformity is increased by 1.45%.
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Authors and Affiliations

Nianyong Zhou
Youxin Zhou
Yingjie Zhao
Qingguo Bao
Guanghua Tang
Wenyu Lv

Using High Level Roadway to Control Gas Emission in a Longwall Mining Face – Numerical Simulation Study

Yongzhen Ma Jianwei Cheng Rui Zhang Zui Wang Dezhi Ran Shuping Sheng Jufeng Zhang Junhong Si Zhaoyang Yu
Archives of Mining Sciences | 2022 | vol. 67 | No 4 | 715-728 | DOI: 10.24425/ams.2022.143683
Keywords high level roadway gob numerical simulation U+HLR ventilation method
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Abstract

With the increase of coal mining depth, the gas content in coal seams could also become larger and larger, which could suddenly cause an inrush of gas into the longwall mining face. It is very dangerous for miners’ safety in the underground. The U-shaped ventilation pattern of longwall mining face that underground coal mines currently use is not enough to deliver sufficient air quantities to dilute gases in mining faces, which could result in the gas concentration over the required celling limit by government laws. Thus, the mine must stop production. In this paper, the high level roadway (HLR) is designed and the U + HLR new ventilation pattern is proposed to control gas emission in a longwall mining face. Using computational fluid dynamics simulation (CFD) software, the flow field and gas transportation in the mine gob are studied. The optimized ventilation parameters are summarized. It is found that the best vertical distance of the HLR is 35 m over the coal seam and the horizontal distance is 25 m from the air return roadway. It is recommended that the negative suction pressure design of the high level roadway should be ranged from 9000 Pa to 10000 Pa. Based on the study outcomes, the gas emission could be well controlled in mining faces and avoid any gas disaster accidents.
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Authors and Affiliations

Yongzhen Ma
1
ORCID: ORCID
Jianwei Cheng
1
ORCID: ORCID
Rui Zhang
1
Zui Wang
1
Dezhi Ran
1
Shuping Sheng
1
Jufeng Zhang
2
Junhong Si
3
Zhaoyang Yu
4
  1. China University of Mining and Technology, China
  2. Longdong University, China
  3. North China Institute of Science and Technology, China
  4. Guizhou University, China

Study on the Three-Phase Flow of the Water Transfer Export Elbow of Natural Gas Hydrate

Wei Chen Hai-liang Xu Bo Wu Fang-qiong Yang
Archives of Mining Sciences | 2022 | vol. 67 | No 2 | 239-258 | DOI: 10.24425/ams.2022.141456
Keywords deep-sea mining natural gas hydrates three-phase flow numerical simulation
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Abstract

The Euler multiphase flow and population equilibrium model were used to simulate the three-phase flow field in the bubble expansion stage of the outlet curved pipe section. The influence of the ratio of the bending diameter and the volume fraction of the gas phase on the pressure loss is revealed, and the safety range of the optimum bending diameter ratio and the volume fraction of the outlet gas phase is determined. The results show that the three-phase flow in the tube is more uniformly distributed in the vertical stage, and when the pipe is curved, the liquid-phase close to the pipe wall gathers along the pipe flank to the outside of the pipe, the solid phase is transferred along the pipe flank to the inside of the pipe, and the gas phase shrinks along the pipe flank to the inner centre. The maximum speed of each phase of the three-phase flow in the elbow is at the wall of the tube from 45° to 60° inside the elbow, and the distribution law along the axial direction of the pipe is about the same as the distribution law of volume fraction. The pressure loss of the elbow decreases with the increase of the bend diameter ratio, when the bend diameter ratio increases to 6, the pressure loss of the pipe decreases sharply, and the pressure loss decreases slowly with the increase of the bend diameter ratio. When the gas phase volume score in the elbow reaches 70%, there will be an obvious wall separation phenomenon, to keep the system in a stable working state and prevent blowout, the gas phase volume score should be controlled within 60%.
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Authors and Affiliations

Wei Chen
1 2 3
ORCID: ORCID
Hai-liang Xu
2 3
ORCID: ORCID
Bo Wu
2 3
ORCID: ORCID
Fang-qiong Yang
2 3
ORCID: ORCID
  1. Hunan University of Humanities, Department of Energy and Electrical Engineering, Science and Technology, Loudi, Hunan 417000, China
  2. Central South University, School of Mechanical and Electrical Engineering, Changsha, Hunan 410083, China
  3. State Key Laboratory of High Performance Complex Manufacturing, Changsha, Hunan 410083, China

Experimental and numerical analysis of vortex generators designed for utility vehicles

Ramesh Kumar Chidambaram Rajesh Kanna Poomanandan Gopal Senthil Kumar Arumugam
Archives of Thermodynamics | 2023 | vol. 44 | No 3 | 217-240 | DOI: 10.24425/ather.2023.147545
Keywords Vortex generator Pressure coefficient Numerical simulation drag force
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Abstract

The main goal of today’s car designers is to minimize fuel consumption in all possible ways at the same time maintaining the vehicle’s performance as usual. The goal of this work is to study the effect of adding a vortex generator (VG) on the aerodynamics of the vehicle and fuel economy. Both theoretical and experimental works were carried out and the outcomes of the numerical simulations are contrasted with those of the experimental results. A utility vehicle model with a scale ratio of 1:15 was used as a test model. Experimental research has been done on the fluctuation of the coefficient of pressure, dynamic pressure, and coefficients of lift and drag with and without VG on the roof of a utility vehicle. The delta-shaped VG was put to the test both numerically and experimentally. At a velocity of 2.42 m/s, it is observed that the addition of VG can raise the pressure coefficient by about 17%. When compared to the vehicle model without vortex generators, the velocity profile of the ccomputational fluid dynamics analysis shows that at the back end of the vehicle, the wake has been minimized with VG.
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Authors and Affiliations

Ramesh Kumar Chidambaram
1
Rajesh Kanna
2
Poomanandan Gopal
3
Senthil Kumar Arumugam
4
  1. Vellore Institute of Technology, Automotive Research Centre, Vellore – 632014, India
  2. Vellore Institute of Technology, CO2 Research and Green Technologies Center, Vellore – 632014, India
  3. Anna University, Department of Automobile Engineering, BIT Campus, Tiruchirappalli, 620024, India
  4. VIT Bhopal University, Bhopal, 466114, India

Numerical research of combustion with a minimum boiler load

Bartłomiej Hernik Wiesław Zabłocki
Archives of Thermodynamics | 2020 | vol. 41 | No 4 | 93-114 | DOI: 10.24425/ather.2020.135855
Keywords numerical simulations Ultra-supercritical boiler coal combustion Minimum boiler load
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Abstract

Power boilers should be characterized by high flexibility in terms of loads, which results from the demand for electricity. In addition to the flexibility of the boiler, it is also important for the boiler to operate under technical minimum conditions while maintaining harmful emissions standards. A boiler operating with a technical minimum should also exhibit a stable combustion process. The paper presents the results of numerical combustion research for the minimum load of the two-pass ultrasupercritical boiler with front wall swirl burners system. The combustion stability for the minimum boiler load of 40% for the three mill system configurations has been demonstrated. Based on the numerical tests carried out in terms of obtaining the most favourable combustion conditions and the emission of harmful substances, the most favourable of them cases was indicated.

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Authors and Affiliations

Bartłomiej Hernik
Wiesław Zabłocki

Improving irrigation system management; A case study: Bahr Sanhoor Canal, Fayoum, Egypt

Amir Sabry Ibrahim
Journal of Water and Land Development | 2022 | No 53 | 1-10 | DOI: 10.24425/jwld.2022.140774
Keywords canal efficiency covering GIS irrigation system management numerical simulation
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Abstract

Realising the need for improving irrigation system management, the Bahr Sanhoor Canal (BSC) was selected as a case study, and the effect of covering a reach with a concrete box culvert where the irrigation canal passes through a crowded rural area on the efficiency of the canal system was examined. The field inspection of the canal system revealed multiple problems. Two alternatives for improving irrigation management were introduced. A local alternative was offered by applying a suitable numerical model to enhance the efficiency of the current status of the canal system, the water level upstream of the covered part reached 13.54 m, this solution will lower the water levels by approximately 2 m, which is below the bank levels at an affordable cost. Additionally, it will help to avoid the risk of inundating the adjacent residential area. A sustainable and environmental alternative was considered to offer a new path in which the covered reach passed outside the residential area. This alternative is permanent and sustainable. Although the proposed second path to the right of the residential area is the long-term recommendation and is sustainable, any path of flow to either the left or right of the BSC will be associated with initial high costs. The two proposed alternatives may help decision makers improve the performance of irrigation systems.
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Authors and Affiliations

Amir Sabry Ibrahim
1
ORCID: ORCID
  1. Civil Engineering Department, Benha Faculty of Engineering, Benha University, Benha, Egypt

Impact Behavior of the Ballistic Targets Package Composed of Dyneema Polymer and High Entropy Alloy Structures

I. Voiculescu V. Geanta T. Chereches P. Vizureanu R. Stefanoiu A. Rotariu D. Mitrica
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 2 | 569-576 | DOI: 10.24425/amm.2022.137792
Keywords ballistic target high entropy alloy Dyneema polymer impact numerical simulation
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Abstract

Ballistic targets are multi-material assemblies that can be made of various materials, such as metal alloys, ceramics, and polymers. Their role is to provide collective or individual ballistic protection against high-speed dynamic penetrators or kinetic fragments. The paper presents the impact behavior with incendiary perforating bullets having 7.62 mm of ballistic packages made of combinations between Dyneema ultra-high-molecular-weight polyethylene and high entropy alloy from alloying system AlCoCrFeNi, by analyzing the dynamic phenomena (deformation, perforation) that take place at high speeds. The geometry evolution of the physical model subjected to numerical simulation allows a very good control over the discretization network and also allows the export for modeling to nonlinear transient phenomena. The results obtained by numerical simulation showed that the analyzed ballistic package does not allow sufficient protection for values of impact velocities over 500 m/sec.
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Authors and Affiliations

I. Voiculescu
1
ORCID: ORCID
V. Geanta
2
ORCID: ORCID
T. Chereches
3
ORCID: ORCID
P. Vizureanu
4
ORCID: ORCID
R. Stefanoiu
2
ORCID: ORCID
A. Rotariu
5
ORCID: ORCID
D. Mitrica
6
ORCID: ORCID
  1. University Politehnica of Bucharest, Faculty of Industrial Engineering and Robotics, 060042 Splaiul Independentei 313, Bucharest, Romania
  2. University Politehnica of Bucharest, Faculty of Materials Science and Engineering, 060042 Splaiul Independentei 313, Bucharest, Romania
  3. UPS PILOR ARM, Laminorului Street, 2, Targoviste, Romania
  4. Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science and Engineering, 67, Dimitrie Mangeron Street, Romania
  5. Military Technical Academy Ferdinand I, 050141, George Cosbuc, 39-49, Bucharest, Romania
  6. National Research-Development Institute for Non-Ferrous and Rare Metals – IMNR, 077145, Biruintei, 102, Pantelimon, Romania

Prediction of Chunky Graphite in Nodular Cast Iron on the Base of Numerical Simulation and Experimental Data

B. Bauer I. Mihalic Pokopec M. Petrič P. Mrvar
Archives of Metallurgy and Materials | 2020 | vol. 65 | No 1 | 343-347 | DOI: 10.24425/amm.2020.131736
Keywords chunky graphite nodular cast iron numerical simulation cooling curve microstructure
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Abstract

Chunky graphite has been recognized for a long time as one of the major problems in production of heavy section nodular cast iron. A great number of studies have been conducted to describe the chunky graphite formation, but a clear understanding of its appearance and a safe mastering of the melt preparation to avoid chunky graphite are not yet available. In the present work the cooling curves were recorded in large cone blocks and standard TA cup. According to measured data from the cone block, melt characteristics and heat transfer coefficient between casting and mould were adjusted in the ProCAST® simulation software. For a near-eutectic nodular cast iron test melt with 0.7 wt. % Ni, relationship between the area of the cone block affected by chunky graphite and simulation software results has been observed, i.e., thermal modulus and time to solidus.

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Authors and Affiliations

B. Bauer
I. Mihalic Pokopec
M. Petrič
P. Mrvar

The Influence of Riser Shape on Feeding Effectiveness of Solidifying Casting

L. Sowa T. Skrzypczak P. Kwiatoń
Archives of Foundry Engineering | 2019 | vol. 19 | No 4 | 91-94 | DOI: 10.24425/afe.2019.129636
Keywords Solidification process Castings defects Numerical simulation Liquid metal flow
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Abstract

The mathematical model and numerical simulations of the solidification of a cylindrical shaped casting, which take into account the process of filling the mould cavity by liquid metal and feeding the casting through the riser during its solidification, are presented in the paper. Mutual dependence of thermal and flow phenomena were taken into account because have an essential influence on solidification process. The effect of the riser shape on the effectiveness of feeding of the solidifying casting was determined. In order to obtain the casting without shrinkage defects, an appropriate selection of riser shape was made, which is important for foundry practice. Numerical calculations of the solidification process of system consisting of the casting and the conical or cylindrical riser were carried out. The velocity fields have been obtained from the solution of momentum equations and continuity equation, while temperature fields from solving the equation of heat conductivity containing the convection term. Changes in thermo-physical parameters as a function of temperature were considered. The finite element method (FEM) was used to solve the problem.

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Authors and Affiliations

L. Sowa
ORCID: ORCID
T. Skrzypczak
ORCID: ORCID
P. Kwiatoń
ORCID: ORCID

A Study of Microstructure and Porosity Formation in High-Pressure Die-Casting

M. Matejka D. Bolibruchová R. Podprocká
Archives of Foundry Engineering | 2021 | vo. 21 | No 4 | 127-130 | DOI: 10.24425/afe.2021.139761
Keywords Al-Si-Cu alloy Returnable material Numerical simulation Porosity Microstructure
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Abstract

The technology of high-pressure die-casting (HPDC) of aluminum alloys is one of the most used and most economical technology for mass production of castings. High-pressure die-casting technology is characterized by the production of complex, thin-walled and dimensionally accurate castings. An important role is placed on the effective reduction of costs in the production process, wherein the combination with the technology of high-pressure die-casting is the possibility of recycling using returnable material. The experimental part of the paper focuses on the analysis of a gradual increase of the returnable material amount in combination with a commercial purity alloy for the production of high-pressure die-castings. The returnable material consisted of the so-called foundry waste (defective castings, venting and gating systems, etc.). The first step of the experimental castings evaluation consisted of numerical simulations, performed to determine the points of the casting, where porosity occurs. In the next step, the evaluation of areal porosity and microstructural analysis was performed on experimental castings with different amounts of returnable material in the batch. The evaluation of the area porosity showed only a small effect of the increased amount of the returnable material in the batch, where the worst results were obtained by the casting of the alloy with 90% but also with 55% of the returnable material in the batch. The microstructure analysis showed that the increase in returnable material in the batch was visibly manifested only by a change in the morphology of the eutectic Si.
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Bibliography

[1] Ragan, E. (2007). Die casting of metals. Prešov, Slovakia. (in Slovak).
[2] Eperješi, Ľ., Malik, J., Eperješi Š. & Fecko D. (2013) Influence of returning material on porosity of die castings. Manufacturing Technology. 13(1), 36-39. DOI: 10.21062/ujep/x.2013/a/1213-2489/MT/13/1/36.
[3] Gaustad, G., Olivetti, E. A. & Kirchain, R. (2012). Improving aluminum recycling: A survey of sorting and impurity removal technologies. Resources Conservation and Recycling. 58, 79-87.
[4] Matejka, M., Bolibruchová, D. & Kuriš, M. (2021). Crystallization of the structural components of multiple remelted AlSi9Cu3 alloy. Archives of Foundry Engineering. 21(2), 41-45. DOI: 10.24425/afe.2021.136096.
[5] Bruna, M., Remišová, A. & Sládek, A. (2019). Effect of filter thickness on reoxidation and mechanical properties of aluminium alloy AlSi7Mg0.3. Archives of Metallurgy and Materials. 3, 1100-1106. DOI: 10.24425/amm.2019.129500.
[6] Bryksi Stunova, B. & Bryksi, V. (2016). Analysis of defects in castings cast by rheocasting method SEED. Archives of Foundry Engineering. 16(3), 15-18. DOI: 10.1515/afe-2016-0041.
[7] Podprocká, R. & Bolibruchová, D. (2017). Iron intermetallic phases in the alloy based on Al-Si-Mg by applying manganese. Archives of Foundry Engineering. 17(3), 217-221. DOI: 10.24425/afe.2020.133321.
[8] Martinec, D., Pastircak, R. & Kantorikova, E. (2020). Using of technology semisolid squeeze casting by different initial states of material. Archives of Foundry Engineering. 20(1), 117-121. DOI: 10.24425/afe.2020.131292.
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Authors and Affiliations

M. Matejka
1
ORCID: ORCID
D. Bolibruchová
1
ORCID: ORCID
R. Podprocká
2
  1. University of Zilina, Faculty of Mechanical Engineering, Department of Technological Engineering, Univerzitna 1, 010 26 Zilina, Slovak Republic
  2. Rosenberg-Slovakia s.r.o., Kováčska 38, 044 25 Medzev, Slovak Republic

Quantitative Prediction of Air Entrainment Defects in Casting Filling Process

Yajun Yin Yao Xie Yingchen Song Xu Shen Xiaoyuan Ji Jianxin Zhou
Archives of Foundry Engineering | 2023 | vol. 23 | No 4 | 117-126 | DOI: 10.24425/afe.2023.146686
Keywords Casting Numerical simulation Gas entrainment defect Filling process
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Abstract

Air entrainment defect is a common type of defect in the casting process, which will seriously affect the quality of the casting. Numerical simulation technology can predict the occurrence of casting defects according to the evolution law of liquid metal in the process of fill ing and solidification. The simulation of air entrainment process is a hot and difficult issue in the field of numerical simulation. The evolution law of air entrainment and the tracking of induced bubbles in the process of metal filling are still lacking. So is the quantitative prediction of trained gas. In this paper, based on the numerical simulation software of Inte CAST, this paper proposes an algorithm for air entrainment search and tracking, which is used to develop a quantitative prediction system for air entrainment. The feasibility of the system is verified through the simulation calculation of the typical test pieces of the air entrainment and the prediction of air entrainment defects of the casting in the process of filling is obtained through the simulation calculation of the actual casting, which can provide a certain guiding role for the optimization of the process in the production practice.
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Bibliography

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Authors and Affiliations

Yajun Yin
1
Yao Xie
2
Yingchen Song
1
Xu Shen
1
Xiaoyuan Ji
1
Jianxin Zhou
1
  1. Huazhong University of Science and Technology, China
  2. State Key Laboratory of Special Rare Metal Materials, China

Casting Quality Improvement by Gating System Optimization

M. Bruna M. Galčík
Archives of Foundry Engineering | 2021 | vo. 21 | No 1 | 132-136 | DOI: 10.24425/afe.2021.136089
Keywords Reoxidation Gating system Numerical simulation Aluminium alloys Mechanical properties
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Abstract

One of the main reason for decreased internal homogeneity of aluminium alloy castings is reoxidation. The resulting products of reoxidation are doubled oxides, so called "bifilms". Submitted paper deals with optimization of gating system design in order to reduce reoxidation processes taking place in mold cavity. Experimental work compares and evaluates three gating systems designs based on non-pressurized and naturally pressurized principles. Unconventional spin trap extension of runner was used in third design. Among the evaluated aspects were: mechanical properties, hot tearing index, visual inspection of average porosity amount, numerical simulation of velocity, turbulence and oxide amount. Paper aim is also to clarify the reoxidation phenomenon by visualization with the aid of ProCAST numerical simulation software. Results of mechanical properties and hot tear index clearly confirmed the positive effect of the naturally pressurized gating system with applied element for velocity reduction.
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Authors and Affiliations

M. Bruna
1
ORCID: ORCID
M. Galčík
1
  1. Department of Technological Engineering, University of Zilina, Univerzitna 1, 010 26 Zilina, Slovakia

Impact of thermal backfill parameters on current-carrying capacity of power cables installed in the ground

Seweryn Szultka Stanisław Czapp Adam Tomaszewski
Bulletin of the Polish Academy of Sciences Technical Sciences | 2023 | 71 | 3 | e145565 | DOI: 10.24425/bpasts.2023.145565
Keywords current-carrying capacity numerical simulations power cables thermal analysis
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Abstract

Proper design of power installations with the participation of power cables buried in homogeneous and thermally well-conductive ground does not constitute a major problem. The situation changes when the ground is non-homogeneous and thermally low-conductive. In such a situation, a thermal backfill near the cables is commonly used. The optimization of thermal backfill parameters to achieve the highest possible current-carrying capacity is insufficiently described in the standards. Therefore, numerical calculations based on computational fluid dynamics could prove helpful for designers of power cable lines. This paper studies the influence of dimensions and thermal resistivity of the thermal backfill and thermal resistivity of the native soil on the current-carrying capacity of power cables buried in the ground. Numerical calculations were performed with ANSYS Fluent. As a result of the research, proposals were made on how to determine the current-carrying capacity depending on the dimensions and thermal properties of the backfill. A proprietary mathematical function is presented which makes it possible to calculate the cable current-carrying capacity correction factor when the backfill is used. The research is expected to fill the gap in the current state of knowledge included in the provisions of standards.
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Authors and Affiliations

Seweryn Szultka
1
ORCID: ORCID
Stanisław Czapp
1
ORCID: ORCID
Adam Tomaszewski
2
ORCID: ORCID
  1. Faculty of Electrical and Control Engineering, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
  2. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland

Frequency of free vibration in systems with power-law restoring force

Ivan Grega Robert Grega Jaroslav Homisin
Bulletin of the Polish Academy of Sciences Technical Sciences | 2021 | 69 | 2 | e136723 | DOI: 10.24425/bpasts.2021.136723
Keywords power-law restoring force nonlinear vibration dimensional analysis numerical simulations
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Abstract

To model the nonlinear behaviour of vibrating systems, Taylor expansion with integer powers is often used. Some systems, however, are inherently nonlinear. In the case of a non-integer real exponent, the power-law system cannot be linearised around the equilibrium position using Taylor expansion. The approach presented here provides a simple estimate of the principal frequency of free vibration in systems with power-law restoring force. Without seeking the precise mathematical form of the output waveform, we only focus on the principal frequency. The first step is the use of dimensional analysis to reduce the number of parameters. Two independent non-dimensional groups are formed and functional dependence between them is sought using numerical simulations. Once this dependence is known, the principal frequency of free vibration can be readily determined for any system properties and any initial conditions. Finally, we compare the numerical results to analytical expressions for a few restoring force exponents.
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Authors and Affiliations

Ivan Grega
1
Robert Grega
2
ORCID: ORCID
Jaroslav Homisin
2
  1. Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, United Kingdom
  2. Faculty of Mechanical Engineering, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovakia

Experimental and Numerical Studies of the Behavior and Energy Absorption of Foam-Filled Circular Tubes

P. Kaczyński J. Karliński M. Hawryluk
Archives of Metallurgy and Materials | 2020 | vol. 65 | No 2 | 521-527 | DOI: 10.24425/amm.2020.132789
Keywords numerical simulation single and double-walled tubes polyurethane foam
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Abstract

Following paper is focused on experimental and numerical studies of the behavior and energy absorption for both: quasi-static and dynamic axial crushing of thin-walled cylindrical tubes filled with foam. The experiments were conducted on single walled and double walled tubes. Unfilled profiles were compared with tubes filled with various density polyurethane foam. All experiments were done in order to possibility of the safety of the elements absorbing collision energy which can applied in car body. The dynamic nonlinear simulations were carried out by means of PAM-CRASH™ explicit code, which is dedicated calculation package to modelling of crush. Computational crushing force, plastic hinges locations and specimens post-crushed geometry found to be convergent with the real experiments results. Conducted experiments allowed to draw conclusion, that crashworthiness ability is directly proportional to foam density. The investigation of the experimental data revealed, that double walled tubes have greater energy absorbing ability. A proposed investigation enable to analyze and chosen of optimal parameters of these elements, which can use in automotive industry as an absorption energy components.

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Authors and Affiliations

P. Kaczyński
J. Karliński
M. Hawryluk

Effect of Electrode Induction Melting Gas Atomization Process on Fine Powder Yields: Continuous Metal Melt Flow

Jialun Wu Min Xia Junfeng Wang Changchun Ge
Archives of Metallurgy and Materials | 2023 | vol. 68 | No 3 | 839-849 | DOI: 10.24425/amm.2023.145446
Keywords gas atomization powder metallurgy numerical simulation computational fluid dynamics
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Abstract

Electrode induction melting gas atomization (EIGA) is a newly developed method for preparing ultra-clean metal powders, and is a completely crucible-free melting and atomization process. Based on conducted several atomization experiments, we found that the fine powder yields obtained during the EIGA process were greatly affected by the status of metal melt flow. While, continuous metal melt flow was beneficial for the yield of fine powders, it was in conflict with the principle described for the vacuum induction melting inert gas atomization (VIGA) process. To understand the critical role of continuous metal melt flow in the EIGA process, a computational fluid dynamics (CFD) approach was developed to simulate the gas atomization process. The D50 particle size of powder prepared by atomization under continuous liquid metal flow was about 70 μm, while that obtained by atomization under non-continuous liquid metal flow was about 100 μm. The diameter distribution results of numerical simulations agreed well with the experimental measurements, which demonstrated the accuracy of our simulation method. This study provides theoretical support for understanding the critical role of continuous metal melt flow and improving fine powder yields in the EIGA process. PACS: 02.60.Cb; 43.28.Py; 41.20.Gz; 81.20.Ev
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Authors and Affiliations

Jialun Wu
1
ORCID: ORCID
Min Xia
1
ORCID: ORCID
Junfeng Wang
1
ORCID: ORCID
Changchun Ge
1
ORCID: ORCID
  1. University of Science & Technology Beijing, Institute of Powder Metallurgy and Advanced Ceramics, Beijing 100083, China

Numerical Simulations of Metallic Foam Safeguarded RC Square Columns under Lateral Soft Impact

Z.Y. Xie
Archives of Civil Engineering | Vol. 66 | No 2 | 3-17 | DOI: 10.24425/ace.2020.131792
Keywords metallic foams RC columns Impact resistance numerical simulation
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Abstract

When a truck impacts on a reinforced concrete (RC) column such as a bridge pier at a high velocity, a large reaction force would generate which would damage the truck, hurt the passengers and destroy the column. Lightweight foams with excellent energy absorbing performance are often used as safeguard constructions to resist impact. The impact behavior can be divided into soft and hard impact. In the case of soft impact, the impacted structure deformation is predominant. In the paper, metallic foam safeguarded RC square columns impacted by a rigid block are simulated using the ABAQUS code software, and the influential characteristic of foam density on the peak impact force and ultimate energy absorption is focused on. The simulated results indicate that the foam safeguard constructions play remarkable role on impact resistance. It is exciting that there appears almost an identical critical foam density corresponding to the minimum peak force and the ultimate energy absorption, which is of great significance for engineering design of this type of safeguard constructions to resist impact.

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Authors and Affiliations

Z.Y. Xie

Effect of surface energy on the contamination characteristics of porcelain double umbrella insulators

Yukun Lv Qian Wang Zeze Chen Jiawen Wang
Archives of Electrical Engineering | 2024 | vol. 73 | No 1 | 235-250 | DOI: 10.24425/aee.2024.148867
Keywords contamination characteristics numerical simulation surface energy XWP2-160 insulator
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Abstract

To explore the influence of surface energy on the contamination characteristics of insulators, COMSOL Multiphysics software was used to simulate the contamination characteristics of XWP 2-160 insulators under wind tunnel conditions, and the rationality of the modified expression of the dynamic deposition model of the contaminated particles was verified. The change of contamination characteristics before and after changing the surface energy of insulators under natural conditions was simulated and analyzed. The results show that under the original surface energy (72 mJ/m 2) and low surface energy (6.7 mJ/m 2) with the increase in particle size, the contamination amount of an insulator surface area decreases first and then increases. When the wind speed is 2 m/s, the change in the particle size has the most pronounced effect on the amount of contamination. The amounts of contamination for the low surface energy are 64–75%, 60–95%, 55–91% and 54–78% lower than those for the original surface energy for particle sizes of 10, 15, 20 and 25 μm, respectively. For the same wind speed, when the size of contamination particles increases, the difference between the ratio of DC and AC contamination accumulation is gradually increasing because of the influence of the electric field force. From the perspective of the insulator preparation process, the development of low surface energy insulators can improve their anti-fouling performance.
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Authors and Affiliations

Yukun Lv
1
Qian Wang
1
Zeze Chen
1
ORCID: ORCID
Jiawen Wang
1
  1. Department of Power Engineering, North China Electric Power University

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