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Abstract

This paper presents a numerical analysis of the thermal-flow characteristics for a laminar flow inside a rectangular microchannel. The flow of water through channels with thin obstacles mounted on opposite walls was analyzed. The studies were conducted with a low Reynolds number (from 20 to 200). Different heights of rectangular obstacles were analyzed to see if geometrical factors influence fluid flow and heat exchange in the microchannel. Despite of the fact that the use of thin obstacles in the microchannels leads to an increase in the pressure drop, the increase in the height of the obstacles favors a significant intensification of heat exchange with the maximum thermal gain factor of 1.9 for the obstacle height coefficient h/H=0.5, which could be acceptable for practical application.
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Bibliography

[1] Y.-T. Yang and S. Yang. Numerical study of turbulent flow in two-dimensional channel with surface mounted obstacle. International Journal of Heat and Mass Transfer, 37(18):2985–2991, 1994. doi: 10.1016/0017-9310(94)90352-2.
[2] K. Sivakumar, T. Sampath Kumar, S. Sivasankar, V. Ranjithkumar, and A. Ponshanmugakumar. Effect of rib arrangements on the flow pattern and heat transfer in internally ribbed rectangular divergent channels. Materials Today: Proceedings, 46(9):3379–3385, 2021. doi: 10.1016/j.matpr.2020.11.548.
[3] T.M. Liou, S.W. Chang, and S.P. Chan. Effect of rib orientation on thermal and fluid-flow features in a two-pass parallelogram channel with abrupt entrance. International Journal of Heat and Mass Transfer, 116:152–165, 2018. doi: 10.1016/j.ijheatmasstransfer.2017.08.094.
[4] W. Yang, S. Xue, Y. He, and W. Li. Experimental study on the heat transfer characteristics of high blockage ribs channel. Experimental Thermal and Fluid Science, 83:248–259, 2017. doi: 10.1016/j.expthermflusci.2017.01.016.
[5] F.B. Teixeira, M.V. Altnetter, G. Lorenzini, B.D. do A. Rodriguez, L.A.O. Rocha, L.A. Isoldi, and E.D. dos Santos. Geometrical evaluation of a channel with alternated mounted blocks under mixed convection laminar flows using constructal design. Journal of Engineering Thermophysics, 29(1): 92–113, 2020. doi: 10.1134/S1810232820010087.
[6] A. Korichi and L. Oufer. Numerical heat transfer in a rectangular channel with mounted obstacles on upper and lower walls. International Journal of Thermal Sciences, 44(7):644–655, 2005. doi: 10.1016/j.ijthermalsci.2004.12.003.
[7] L.C. Demartini, H.A. Vielmo, and S.V. Möller. Numeric and experimental analysis of the turbulent flow through a channel with baffle plates. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 26(2):153–159, 2004. doi: 0.1590/S1678-58782004000200006.
[8] Y.T. Yang and C.Z. Hwang. Calculation of turbulent flow and heat transfer in a porous-baffled channel. International Journal of Heat and Mass Transfer, 46(5):771–780, 2003. doi: 0.1016/S0017-9310(02)00360-5.
[9] G. Wang, T. Chen, M. Tian, and G. Ding. Fluid and heat transfer characteristics of microchannel heat sink with truncated rib on sidewall. International Journal of Heat and Mass Transfer, 148:119142, 2020. doi: 10.1016/j.ijheatmasstransfer.2019.119142.
[10] S. Mahjoob and S. Kashkuli. Thermal transport analysis of injected flow through combined rib and metal foam in converging channels with application in electronics hotspot removal. International Journal of Heat and Mass Transfer, 177:121223, 2021. doi: 10.1016/j.ijheatmasstransfer.2021.121223.
[11] L. Chai, G.D. Xia, and H.S. Wang. Numerical study of laminar flow and heat transfer in microchannel heat sink with offset ribs on sidewalls. Applied Thermal Engineering, 92:32–41, 2016. doi: 10.1016/j.applthermaleng.2015.09.071.
[12] Y. Yin, R. Guo, C. Zhu, T. Fu, and Y. Ma. Enhancement of gas-liquid mass transfer in microchannels by rectangular baffles. Separation and Purification Technology, 236:116306, 2020. doi: 10.1016/j.seppur.2019.116306.
[13] A. Behnampour O.A. Akbari, M.R. Safaei, M. Ghavami, A. Marzban, G.A.S. Shabani, M. Zarringhalam, and R. Mashayekhi. Analysis of heat transfer and nanofluid fluid flow in microchannels with trapezoidal, rectangular and triangular shaped ribs. Physica E: Low-Dimensional Systems and Nanostructures, 91:15–31, 2017. doi: 10.1016/j.physe.2017.04.006.
[14] M.R. Gholami, O.A. Akbari, A. Marzban, D. Toghraie, G.A.S. Shabani, and M. Zarringhalam. The effect of rib shape on the behavior of laminar flow of {oil/MWCNT} nanofluid in a rectangular microchannel. Journal of Thermal Analysis and Calorimetry, 134(3):1611–1628, 2018. doi: 10.1007/s10973-017-6902-3.
[15] O.A. Akbari, D. Toghraie, A. Karimipour, M.R. Safaei, M. Goodarzi, H. Alipour, and M. Dahari. Investigation of rib’s height effect on heat transfer and flow parameters of laminar water-{Al2O3} nanofluid in a rib-microchannel. Applied Mathematics and Computation, 290:135–153, 2016. doi: 10.1016/j.amc.2016.05.053.
[16] B. Mondal, S. Pati, and P.K. Patowari. Analysis of mixing performances in microchannel with obstacles of different aspect ratios. Journal of Process Mechanical Engineering, 233(5):1045–1051, 2019. doi: 10.1177/0954408919826748.
[17] L. Chai, G.D. Xia, and H.S. Wang. Parametric study on thermal and hydraulic characteristics of laminar flow in microchannel heat sink with fan-shaped ribs on sidewalls -- Part 2: Pressure drop. International Journal of Heat and Mass Transfer, 97:1081–1090, 2016. doi: 10.1016/j.ijheatmasstransfer.2016.02.076.
[18] P. Pontes, I. Gonçalves, M. Andredaki, A. Georgoulas, A.L.N. Moreira, and A.S. Moita. Fluid flow and heat transfer in microchannel devices for cooling applications: Experimental and numerical approaches. Applied Thermal Engineering, 218:119358, 2023. doi: 10.1016/j.applthermaleng.2022.119358.
[19] B.K. Srihari, A. Kapoor, S. Krishnan, and S. Balasubramanian. Computational fluid dynamics studies on the flow of fluids through microchannel with intentional obstacles. AIP Conference Proceedings, 2516(1):170003. doi: 10.1063/5.0108550.
[20] T. Grzebyk and A. Górecka-Drzazga. Vacuum microdevices. Bulletin of the Polish Academy of Sciences: Technical Sciences, 60(1):19–23, 2012. doi: 10.2478/v10175-012-0004-y.
[21] M. Kmiotek and A. Kucaba-Piętal. Influence of slim obstacle geometry on the flow and heat transfer in microchannels. Bulletin of the Polish Academy of Sciences: Technical Sciences, 66(2):111–118, 2018. doi: 10.24425/119064.
[22] S. Baheri Islami, B. Dastvareh, and R. Gharraei. An investigation on the hydrodynamic and heat transfer of nanofluid flow, with non-Newtonian base fluid, in micromixers. International Journal of Heat and Mass Transfer, 78:917–929, 2014. doi: 10.1016/j.ijheatmasstransfer.2014.07.022.
[23] S. Baheri Islami, B. Dastvareh, and R. Gharraei. Numerical study of hydrodynamic and heat transfer of nanofluid flow in microchannels containing micromixer. International Communications in Heat and Mass Transfer, 43:146–154, 2013. doi: 10.1016/j.icheatmasstransfer.2013.01.002.
[24] C.K. Chung, C.Y. Wu, and T.R. Shih. Effect of baffle height and reynolds number on fluid mixing, Microsystem Technologies, 14(9-11):1317–1323, 2008, doi: 10.1007/s00542-007-0511-1.
[25] I. Adina R&D, Theory and Modling Guide, Vollume III: ADINA CFD&FSI, Report ARD. 2019.
[26] P.J. Roache. Verification and Validation in Computational Science and Engineering. Hermosa Publishers, 1998.
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Authors and Affiliations

Małgorzata Kmiotek
1
ORCID: ORCID
Robert Smusz
1
ORCID: ORCID

  1. Rzeszow University of Technology, The Faculty of Mechanical Engineering and Aeronautics, Rzeszow, Poland
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Abstract

This paper presents the study of the impact of vibration induced by the movement of the railway rolling stock on the Forum Gdańsk structure. This object is currently under construction and is located over the railway tracks in the vicinity of the Gdańsk Główny and Gdańsk Śródmieście railway stations. The analysis covers the influence of vibrations on the structure itself and on the people within. The in situ measurements on existing parts of the structure allow us to determine environmental excitations used for validation and verification of the derived FEM model. The numerical calculations made the estimates of the vibration amplitudes propagating throughout the whole structure possible.

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Authors and Affiliations

M. Miśkiewicz
Ł. Pyrzowski
M. Rucka
K. Wilde
J. Chróscielewski
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Abstract

The object of the present study is to investigate the influence of damping uncertainty and statistical correlation on the dynamic response of structures with random damping parameters in the neighbourhood of a resonant frequency. A Non-Linear Statistical model (NLSM) is successfully demonstrated to predict the probabilistic response of an industrial building structure with correlated random damping. A practical computational technique to generate first and second-order sensitivity derivatives is presented and the validity of the predicted statistical moments is checked by traditional Monte Carlo simulation. Simulation results show the effectiveness of the NLSM to estimate uncertainty propagation in structural dynamics. In addition, it is demonstrated that the uncertainty in damping indeed influences the system response with the effects being more pronounced for lightly damped structures, higher variability and higher statistical correlation of damping parameters.

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Authors and Affiliations

B. Tiliouine
B. Chemali
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Abstract

This study aims to design a novel air cleaning facility which conforms to the current situation in China, and moreover can satisfy our demand on air purification under the condition of poor air quality, as well as discuss the development means of a prototype product. Air conditions in the operating room of a hospital were measured as the research subject of this study. First, a suitable turbulence model and boundary conditions were selected and computational fluid dynamics (CFD) software was used to simulate indoor air distribution. The analysis and comparison of the simulation results suggested that increasing the area of air supply outlets and the number of return air inlets would not only increase the area of unidirectional flow region in main flow region, but also avoid an indoor vortex and turbulivity of the operating area. Based on the summary of heat and humidity management methods, the system operation mode and relevant parameter technologies as well as the characteristics of the thermal-humidity load of the operating room were analyzed and compiled. According to the load value and parameters of indoor design obtained after our calculations, the airflow distribution of purifying the air-conditioning system in a clean operating room was designed and checked. The research results suggested that the application of a secondary return air system in the summer could reduce energy consumption and be consistent with the concept of primary humidity control. This study analyzed the feasibility and energy conservation properties of cleaning air-conditioning technology in operating rooms, proposed some solutions to the problem, and performed a feasible simulation, which provides a reference for practical engineering.

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Authors and Affiliations

X.R. Ding
Y.Y. Cino
Y.Y. Chen
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Abstract

In the experiment, bubbles were generated from two brass nozzles with inner diameters of 1.1 mm. They were submerged in the glass tank filled with distilled water. There have been measured the air pressure fluctuations and the signal from the laser-phototransistor sensor. For analysis of the pressure signal the correlation (the normalized cross - correlation exponent) and non-linear analyses have been used. It has been shown that hydrodynamic interactions between bubbles can lead to bubble departure synchronization. In this case the bubble departures become periodic. The results of calculation of correlation dimension and the largest Lyapunov exponent confirm that hydrodynamic bubble interactions observed for 4 mm spacing between nozzels cause the periodic bubble departures from two neighbouring nozzles.
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Authors and Affiliations

Romuald Mosdorf
Tomasz Wyszkowski
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Abstract

The goal of this research is to achieve close to real-time dynamics performance for allowing auto-pilot in-the-loop testing of unmanned ground vehicles (UGV) for urban as well as off-road scenarios. The overall vehicle dynamics performance is governed by the multibody dynamics model for the vehicle, the wheel/terrain interaction dynamics and the onboard control system. The topic of this paper is the development of computationally efficient and accurate dynamics model for ground vehicles with complex suspension dynamics. A challenge is that typical vehicle suspensions involve closed-chain loops which require expensive DAE integration techniques. In this paper, we illustrate the use the alternative constraint embedding technique to reduce the cost and improve the accuracy of the dynamics model for the vehicle.

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Authors and Affiliations

Abhinandan Jain
Calvin Kuo
Paramsothy Jayakumar
Jonathan Cameron
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Abstract

The paper describes the design and multibody dynamic analysis of a mechanically interconnected suspension, as applied to a small off-road vehicle. Interconnected suspensions use some sort of connection between the axles of a vehicle in order improve ride quality or vehicle handling. In principle, the connection may be hydraulic, pneumatic, or mechanical, but for installation in a typical passenger car, a mechanical connection would likely be impractical due to weight and complexity. In this paper, the vehicle in question is the University of Windsor SAE Baja off-road competition vehicle, and novel mechanical design is proposed. A multibody dynamic analysis is performed on the proposed design using the EoM open source multibody software developed by theUniversity ofWindsorVehicle Dynamics and Control research group in order to assess any potential performance improvements.

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Bibliography

[1] E. Zapletal. Balanced suspension. SAE Technical Paper 2000-01-3572, 2000.
[2] J.F. Buj. Integral suspension system for motor vehicles based on passive components. SAE Technical Paper 2002-01-3105, 2002.
[3] G. Rideout, R.J. Anderson. Experimental testing and mathematical modeling of the interconnected hydragas suspension system. SAE Technical Paper 2003-01-0312, 2003.
[4] J.R. Wilde, G.J. Heydinger, D.A. Guenther, T.P. Mallin, A.M. Devenish. Experimental evaluation of fishhook maneuver performance of a kinetic suspension system. SAE Technical Paper 2005- 01-0392, 2005.
[5] J.R. Wilde, G.J. Heydinger, D.A. Guenther. ADAMS simulation of ride and handling performance of the Kinetic™ suspension system. SAE Technical Paper 2006-01-1972, 2006.
[6] M.C. Smith, G.W. Walker. Interconnected vehicle suspension. Journal of Automobile Engineering, 219(3):295–307, 2005. doi: 10.1243/095440705X6578.
[7] B. Mavroudakis, P. Eberhard. Mode decoupling in vehicle suspensions applied to race cars. In Proceedings of the III European Conference on Computational Mechanics Solids, Structures and Coupled Problems in Engineering, Lisbon 2006.
[8] D. Cao, S. Rakheja, C.Y. Su. Roll and pitch-plane coupled hydro-pneumatic suspension. Vehicle System Dynamics, 48(3):361–386, 2010. doi: 10.1080/00423110902883251.
[9] B.P. Minaker, X. Yang, S. Li. Design optimization of an SAE Baja vehicle using the EoM open source multibody dynamics code. Proceedings of The Canadian Society for Mechanical Engineering International Congress, 2014
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Authors and Affiliations

Bruce P. Minaker
1
Zheng Yao
1

  1. Department of Mechanical,Automotive & Materials Engineering, University of Windsor, Canada
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Abstract

Mining tremors may have an impact on the safety risk of steel pipelines through their effects. It is therefore important to quantify the impact of a high-energy mining tremor in terms of strength. In addition, a comparison of the results obtained with the effect of a seismic tremor can illustrate the scale of such a hazard. Recently, this has been a very frequently raised issue in the area of surface protection against negative mining impacts and the protection of post-mining areas. Ensuring safe use is particularly important for gas transmission elements. This paper presents the results of a comparative analysis of the impact of mining tremors and seismic impacts on a specimen steel pipeline segment. The analyzed pipeline is located in the eastern part of Poland in the area of paraseismic impacts of the LGCD (Legnica-Glogow Copper District) mine. For this purpose, an analytical approach was used to assess the impact of seismic wave propagation on underground linear infrastructure facilities. Accelerogram records for the 02-06-2023 seismic tremor from Turkey and the mining tremor for 11-25-2020 were used. In the case of the design of underground pipelines, the cross-section of the element for which measures describing wall stress and the ovalization of the cross-section are determined is usually considered. In the situation of the influence of seismic wave propagation or so-called permanent ground deformation, the response of the pipeline in the longitudinal direction is analyzed. As a final result, longitudinal strains transferred to the pipeline as a consequence of the propagating seismic wave and mining tremor were determined. The absolute difference between the deformations in the ground and along the length of the pipeline was determined. This type of analysis has not been carried out before and provides new insights into the topic of paraseismic impacts on the scale of their interaction with natural earthquakes. Mining tremor data was obtained from the mine’s seismological department. The seismic tremor data, on the other hand, was downloaded via the publicly available ESM (Engineering Strong- Motion Database).
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Authors and Affiliations

Janusz Rusek
1
ORCID: ORCID
Leszek Słowik
2
ORCID: ORCID
Krzysztof Tajduś
1
ORCID: ORCID

  1. AGH University of Krakow al. Adama Mickiewicza 30, 30-059 Krakow, Poland
  2. ITB Building Research Institute ul. Filtrowa 1, 00-611 Warsaw, Poland
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Abstract

The paper presents a new kind of vibrator, called the intelligent vibrator, which is an integrated set of two inert vibrators supplied by asynchronous squirrel-cage motors, equipped with digital control system, the readout system of the position of unbalanced masses, and inverter supply system. The paper presents a model of the prototype of the machine and exemplary run-times.
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Authors and Affiliations

Mariusz Giergiel
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Abstract

New model of the simulation of the airbag inflation process, taking into account the influence of the airbag environment on the folding process, have been proposed. Equations describing a new model and the used numerical schemes were presented. The differences of the airbag fabric skin motion during the folding process, obtained by the use of different process models (existing and proposed), have been presented on the simple geometry examples. From the analysis of obtained results one acknowledged that the proposed model should be used in all calculations of the airbag operation in non-typical situations, out-of position occupants, side airbags, particularly in the case of small distances between the closed airbag and the elements of the body of the protected person.
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Authors and Affiliations

Sylwester Tudruj
ORCID: ORCID
Janusz Piechna
ORCID: ORCID
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Abstract

The paper presents the numerical model of a supply vessel-load-crane-offshore vessel system for simulation of heave motion and dynamic analysis of the system during critical phases of the handling operation: taking the load off from and lowering it to a moving base. The model enables extreme forces in elements and deflection of the structure to be determined. Different operating and emergency conditions can be simulated (e.g. horizontal motion of a supply vessel). The elaborated software can be applied also for determination of derated load charts and ultimate crane capacity (sequence of failure).
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Authors and Affiliations

Marek Osiński
Andrzej Maczyński
Stanisław Wojciech
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Abstract

The paper discusses an occurrence or latent reactions in the direction perpendicular to the movement of the suspension systems in vibratory machines supported by parallel leaf springs. These reactions occur despite an apparent lack of any forces acting in that direction and may - for long machine bodies - reach values comparable with the exciting force of the vibrator. Analytical relationships allowing for estimation of the value of reactions were derived. The obtained results were verified by means of the Geometric Element Method as well as by the performed experiments.
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Authors and Affiliations

Jerzy Michalczyk
Piotr Czubak
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Abstract

Dynamic stability analysis of the World Class Glider PW-5 has been presented. Glider was assumed to be a rigid body of three degrees of freedom - two linear displacements and one rotation - all in the plane of symmetry. Responses of the glider due to gust and deflection of elevator have been determined. The Laplace transform has been applied to convert the differential equations into algebraic ones. The transformed algebraic equations, after a number of manipulations have been solved for the output variables. Partial-fraction expansions have been performed to obtain the inverse Laplace transforms from the Laplace transform table. Although some restricting assumptions have been made (rigid body, small disturbances) the presented results are original and have not been presented before. The airworthiness regulations (JAR, FAR) do not require performing dynamic analysis in order the glider to be granted a Certificate of Airworthiness by the national aviation authority. To certificate the glider it is sufficient to prove static stability by means of in-flight tests. Flying qualities are qualitatively estimated basing on subjective opinions of the test pilots
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Authors and Affiliations

Zdobysław Goraj
Adam Przekop
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Abstract

This paper presents the application of a co-simulation approach for the simulation of frictional contact in general-purpose multibody dynamics to a rotorcraft dynamics problem. The proposed approach is based on the co-simulation of a main problem, which is described and solved as a set of differential algebraic equations, with a subproblem that is characterized by nonsmooth dynamics events and solved using a timestepping technique. The implementation and validation of the formulation is presented. The method is applied to the analysis of the droop and anti-flap contacts of helicopter rotor blades. Simulations focusing on the problem of blade sailing are conducted to understand the behavior and assess the validity of the method. For this purpose, the results obtained using a contact model based on Hertzian reaction forces at the interface are compared with those of the proposed approach.

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Authors and Affiliations

Matteo Fancello
Marco Morandini
Pierangelo Masarati
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Abstract

The dynamics of the turning process of a thin-walled cylinder in manufacturing is modeled using flexible multibody system theory. The obtained model is time varying due to workpiece rotation and tool feed and retarded, due to repeated cutting of the same surface. Instabilities can occur due to these consecutive cuts that must be avoided in practical application because of the detrimental effects on workpiece, tool and possibly the machine. Neglecting the small feed, the stability of the resulting periodic system with time-delay can be analyzed using the semi-discretization method. The use of an adaptronic tool holder comprising actuators and sensors to improve the dynamic stability is then investigated. Different control concepts, two collocated and two model-based, are implemented in simulation and tuned to increase the domain of stable cutting. Cutting of a moderately thin workpiece exhibits instabilities mainly due to tool vibration. In this case, the stability boundary can be significantly improved. When the instability is due to workpiece vibration, the collocated concepts fail completely. Model based concepts can still obtain some improvements, but are sensitive to modeling errors in the coupling of workpiece and tool.

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Authors and Affiliations

Achim Fischer
Peter Eberhard
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Abstract

Main energy conversion machinery used and to be used in cogeneration systems are schematically described. Some assets of the distributed generation are pointed out and small-scale cogeneration systems designed for energy units of distributed cogeneration are described.

In the small scale, turbines and bearings are a source of specific problems connected with securing stable rotor operation. Accepted has been two kinds of high speed micro-turbines of electric power about 3 KW with multistage axial and radial rotors supported on foil bearings. A concept which becomes more and more attractive takes into account a low-boiling agent, which is normally used in the thermal cycle of the micro-turbine, as the lubricating liquid in the bearings (so-called ORC based systems). Of some importance is the operation of these machines at a low noise emission level, sine being parts of the household equipment they could disturb the calm of the residents. The scope of the present article is limited to the discussion of dynamic characteristics of the selected design. The properties of the rotor combined with slide bearings (foil bearings in this particular case) were taken under investigation. A combination of this type is a certain novelty since a typical modal analysis of such objects refers to a rotor itself. Analysing the dynamic state of the "home" power plants requires qualitatively novel research tools.

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Authors and Affiliations

Jan Kiciński
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Abstract

This paper presents the design methodology of a small guided bomb for Unmanned Aerial Vehicles. This kind of next-generation munition has recently gained a lot of attention in the military market. The bomb is planned to be equipped with inertial measurement unit and infrared seeker.The nose shape and fin optimization procedure was described shortly. Aerodynamic characteristics were calculated by means of theoretical and engineering-level methods. The flight dynamics model of the bomb was obtained and implemented in Simulink software. The numerical simulations of uncontrolled and controlled trajectories were compared. The results indicate that the usage of such a guided small munition, like the designed bomb, might improve significantly the offensive capabilities of Unmanned Aerial Vehicles.
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Authors and Affiliations

Mariusz Jacewicz
Robert Głębocki
Adrian Szklarski
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Abstract

The main aim of this analysis is to consider a mutual interference between aircraft motion and surrounding flow field. Euler flow model for inviscid, compressible gas and aircraft flight dynamics model was used to analyse quick dynamic manoeuvres. For such manoeuvres, aerodynamic hysteresis has a great influence on aircraft dynamics, which cannot be simulated with the assumption of quasi-steady aerodynamics. On the other hand, the aircraft motion as a rigid body strongly influences the flow field around itself. To account for this mutual interference, the Euler flow equations were used to obtain aerodynamic forces and moments acting on a simplified aircraft configuration (main wing+ tailplane only) during pull-out manoeuvre, and the flight dynamics equations of motion were used to describe dynamics of an aircraft. Initial conditions for the flight dynamics equation of motion were settled up coming from the solution of the Euler flow model. As a test case, a weak pull-out manoeuvre was selected. During this manoeuvre, the highest value of angle of attack doesn't exceed 12 degrees - the value which can be obtained from the classical approach based on flight dynamics equations of motion with quasisteady aerodynamics. However, coupled Euler flight dynamic model has much wider applicability, and can be used for the analysis of manoeuvres at high angles of attack, including large scale separation at sharp edges, unsteadiness and flow asymmetries even for symmetrical undisturbed flowficld case. This method, if successfully verified to a number of important flight manoeuvres (such as spin, Cobra manoeuvre, roll at high angles of attack and other) can open a new, very promising field in the analysis of aircraft dynamics.
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Authors and Affiliations

Tomasz Iglewski
Zdobysław Goraj
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Abstract

In order for the ultimate state methods to be applied in dimensioning of the load-bearing elements in a conveyance, it is required that their design loads during their normal duty cycle and under the emergency braking conditions should be first established. Recently, efforts have been made to determine the interaction forces between the shaft steelwork and the conveyance under the normal operating condition [1,2]. Thus far, this aspect has been mostly neglected in design engineering. Measurement results summarised in this paper and confronted with the theoretical data [3] indicate that the major determinant of fatigue endurance of conveyances is the force acting horizontally and associated with the conveyance being hoisted in relation to the vertical force due to the weight of the conveyance and payload.
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Bibliography

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[2] S. Wolny, F. Matachowski, Operating Loads of the Shaft Steelwork – Conveyance System dne to Ranchon Irregularities of the Guiding Strings. Arch. Min. Sci. 55 (3), 589-603 (2010).
[3] S. Wolny, Wybrane problemy wytrzymałościowe w eksploatacji górniczych urządzeń wyciągowych. Monografia. Problemy Inżynierii Mechanicznej i Robotyki, AGH, Nr 20, Kraków (2003).
[4] M. Płachno, Metoda dynamiczna badań stanu zmienności naprężeń w cięgnach naczyń wyciągowych powodowanego nierównościami torów prowadzenia. In monograph: Transport szybowy 2007, Wydawnictwo KO MAG, Gliwice, II , 51-60 (2007).
[5] M. Płachno, Mathematical model of transverse vibrations of a high-capacity mining skip due misalignment of the guiding tracks in the hoisting shaft. Arch. Min. Sci. 63 (1), 3-26 (2018).
[6] D . Fuchs, H. Noeller, Untersuchungen an Haupttraggliedern hochbeanspruchter Fördermittel. Sonderabdruck aus Glückauf 124 (9), 512-514 (1998).
[7] M. Płachno, Z. Rosner, Możliwości wczesnego wykrywania procesów zmęczeniowych w cięgnach naczyń wyciągów górniczych. Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie, Wydanie Specjalne, 241-246 (1997).
[8] S. Wolny, Interactions in mechanical systems due to random inputs on the example of a mine hoist. International Education & Research Journal, Engineering 1 (5), 70-74 (2015).
[9] S. Wolny, Displacements in mechanical systems due to random inputs in a mine hoist installation. Engineering Transactions 65 (3), 513-522 (2017).
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[11] A . Pieniążek, J. Weiss, A. Winiarz, Procesy stochastyczne w problemach i zadaniach. Wydawnictwo Politechniki Krakowskiej, Kraków (1999).
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Authors and Affiliations

Stanisław Wolny
1
ORCID: ORCID

  1. AGH University of Science and Technology, Al. A. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

The study addresses two groups of issues occurring in modeling and experimental studies of multicomponent nonisobaric diffusion in macroporous materials. The dynamics of such processes is described in terms of systems of nonlinear partial differential equations. A method of orthogonal collocation for resolving the equations is proposed and compared with the method of lines. The second group of problems presented involves numerical simulations of diffusion in aWicke–Kallenbach diffusion cell. Such an apparatus is used in experimental studies. Particular attention is paid to diffusion in a cell closed from both sides. This is an analogue of the Duncan–Toor experiment. The effect of the number of diffusing components and their initial concentrations on the dynamics of diffusion in binary and ternary solution was studied. Hitherto unknown dynamic properties of such processes were detected and discussed.
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Authors and Affiliations

Katarzyna Bizon
1
ORCID: ORCID
Bolesław Tabiś
1

  1. Cracow University of Technology, Faculty of Chemical Engineering and Technology, ul. Warszawska 24, 31-155 Kraków, Poland
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Abstract

In this paper, quanizted multisine inputs for a maneuver with simultaneous elevator, aileron and rudder deflections are presented. The inputs were designed for 9 quantization levels. A nonlinear aircraft model was exited with the designed inputs and its stability and control derivatives were identified. Time domain output error method with maximum likelihood principle and a linear aircraft model were used to perform parameter estimation. Visual match and relative standard deviations of the estimates were used to validate the results for each quantization level for clean signals and signals with measurement noise present in the data. The noise was included into both output and input signals. It was shown that it is possible to obtain accurate results when simultaneous flight controls deflections are quantized and noise is present in the data.

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Authors and Affiliations

P. Lichota
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Abstract

The advance of technical state criteria for elements of mining hoists demands a basic strength-fatigue analysis where the real values of loads and the real time function of the load variability could be used. That problem concerns also the suspension gear of skip and balance ropes, where fatigue durability should be considered as time function related to the hoist facility type. Such objective can not be achieved without comprehensive study of the dynamics of processes both in the regular operation of the facility and in its emergency states. In this work the author presents some considerations, that are however, limited to the analysis of dynamic phenomena observed in the condition of the emergency braking of the hoist facility. The results were verified by load measurements taken for some elements of the analysed real object system.
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Authors and Affiliations

Stanisław Wolny
ORCID: ORCID
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Abstract

A heterogeneous Bertrand duopoly game with bounded rational and adaptive players manufacturing differentiated products is subject of investigation. The main goal is to demonstrate that participation of one bounded rational player in the game suffices to destabilize the duopoly. The game is modelled with a system of two difference equations. Evolution of prices over time is obtained by iteration of a two dimensional nonlinear map. Equilibria are found and local stability properties thereof are analyzed. Complex behavior of the system is examined by means of numerical simulations. Region of stability of the Nash equilibrium is demonstrated in the plane of the speeds of adjustment. Period doubling route to chaos is presented on the bifurcation diagrams and on the largest Lyapunov characteristic exponent graph. Lyapunov time is calculated. Chaotic attractors are depicted and their fractal dimensions are computed. Sensitive dependence on initial conditions is evidenced.

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Authors and Affiliations

Tomasz Dubiel-Teleszyński
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Abstract

Plate fin-tube heat exchangers fins are bonded with tubes by means of brazing or by mechanical expansion of tubes. Various errors made in the process of expansion can result in formation of an air gap between tube and fin. A number of numerical simulations was carried out for symmetric section of plate fin-tube heat exchanger to study the influence of air gap on heat transfer in forced convection conditions. Different locations of air gap spanning 1/2 circumference of the tube were considered, relatively to air flow direction. Inlet velocities were a variable parameter in the simulations (1– 5 m/s). Velocity and temperature fields for cases with air gap were compared with cases without it (ideal thermal contact). For the case of gap in the back of the tube (in recirculation zone) the lowest reduction (relatively to the case without gap) of heat transfer rate was obtained (average of 11%). The worst performance was obtained for the gap in the front (reduction relatively to full thermal contact in the average of 16%).

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Authors and Affiliations

Dariusz Andrzejewski
Marcin Łęcki
Artur Gutkowski

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