Jaroslaw Krzywanski, Marta Wesolowska, Artur Blaszczuk, Anna Majchrzak, Maciej Komorowski and Wojciech Nowak
The purpose of this paper is to first present the key features of the fuzzy logic (FL) approach as a cost-effective technique in simulations of complex systems and then…
Abstract
Purpose
The purpose of this paper is to first present the key features of the fuzzy logic (FL) approach as a cost-effective technique in simulations of complex systems and then demonstrate the formulation and application of the method.
Design/methodology/approach
The FL approach is used as an alternative method of data handling, considering the complexity of analytical and numerical procedures and high costs of empirical experiments. The distance from gas distributor, the temperature and the voidage of the bed, flue gas velocity and the load of the boiler are the input parameters, whereas the overall heat transfer coefficient for the membrane walls constitutes the output. Five overlapping sigmoid and constant linguistic terms are used to describe the input and the output data, respectively. The Takagi–Sugeno inference engine and the weighted average defuzzification methods are applied to determine the fuzzy and crisp output value, respectively.
Findings
The performed FL model allows predicting the bed-to-wall heat transfer coefficient in a large-scale 670 t/h circulating fluidized bed (CFB) boiler. The local heat transfer coefficients evaluated using the developed model are in very good agreement with the data obtained in complementary investigations.
Originality/value
The performed model constitutes an easy-to-use and functional tool. The new approach can be helpful for further research on the bed-to-wall heat transfer coefficient in the CFB units.
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This study aims to demonstrate what myths of and about science are reproduced in this popular cultural work (movie – “Oppenheimer”). This is done by examining the unconscious…
Abstract
Purpose
This study aims to demonstrate what myths of and about science are reproduced in this popular cultural work (movie – “Oppenheimer”). This is done by examining the unconscious hegemonic positions supported by the reproduction of stereotypical and mythical images of science.
Design/methodology/approach
Content/Text Analysis: The conceptual analysis of a cultural text – a film (“Oppenheimer”) – through a theoretical apparatus (B. Latour’s theory).
Findings
The film demonstrates its reproduction of three distinct elements. Firstly, it exhibits classic scientistic clichés pertaining to technoscience. Secondly, it highlights the replication of the individualized monomyth about the (super) hero, leading to the exclusion of the intricate conditions of technoscience’s existence. Lastly, the film aligns with the Californian ideology, as proposed by Barbrook.
Originality/value
The value of the text is twofold: (1) To show that the classical approaches of Bruno Latour are still relevant. (2) To show what hidden premises and myths about technoscience are being propagated through a work of pop culture (the film “Oppenheimer”) and, in effect, to show what kind of influence of cultural hegemony is at work here.
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Andrzej Demenko, Kay Hameyer, Stefan Kulig, Lech Nowak, Krzysztof Zawirski and Wojciech Pietrowski
The purpose of this paper is to present a modification of the Park variable transformation for a three‐phase wye‐connected winding without neutral wire. A new physical…
Abstract
Purpose
The purpose of this paper is to present a modification of the Park variable transformation for a three‐phase wye‐connected winding without neutral wire. A new physical interpretation of the winding equivalent circuit is proposed.
Design/methodology/approach
An equivalent circuit representing reluctance motor stator winding is rearranged to enable easier physical interpretation of obtained voltage equation. The Park transformation and constraints resulting from Kirchhof's laws are then applied to obtain a two‐axis mathematical model of the motor.
Findings
A new physical two‐phase interpretation of the voltage equation for a three‐phase wye‐connected winding without neutral wire is proposed. A novel two‐axis transformation is formulated for all variables. Compared to the Park transformation, which is the same for all variables, in the proposed transformation its matrices for currents and voltages/flux linkages are different, yet strongly interconnected.
Research limitations/implications
The proposed transformation is formulated for a specific type of winding connection scheme. Therefore, it is limited in its application.
Practical implications
From the practical point of view, the proposed transformation could be very useful as it applies to the most popular stator winding connection scheme. Its main advantages are fewer number of trigonometric parameters in the matrices and measurability of all currents and voltages present in its voltage equations. It could be of special importance for electric machines with non‐sinusoidal field distribution (e.g. Brushless DC).
Originality/value
The paper presents a new type of variable transformation for three‐phase electric machines with wye‐connected windings without neutral wire. Proposed transformation combines different transformations for currents and voltages/flux linkages.
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Wojciech P. Adamczyk, Pawel Kozolub, Gabriel Węcel and Arkadiusz Ryfa
The purpose of this paper is to show possible approaches which can be used for modeling complex flow phenomena caused by swirl burners combined with simulating coal combustion…
Abstract
Purpose
The purpose of this paper is to show possible approaches which can be used for modeling complex flow phenomena caused by swirl burners combined with simulating coal combustion process using air- and oxy-combustion technologies. Additionally, the response of exist boiler working parameter on changing the oxidizer composition from air to a mixture of the oxygen and recirculated flue gases is investigated. Moreover, the heat transfer in the superheaters section of the boiler was taken into account by modeling of the heat exchange process between continuum phase and three stages of the steam superheaters.
Design/methodology/approach
An accurate solution of the flow field is required in order to predict combustion phenomena correctly for numerical simulations of the industrial pulverized coal (PC) boilers. Nevertheless, it is a very demanding task due to the complicated swirl burner construction and complex character of the flow. The presented simulations were performed using the discrete phase model for tracking particles and combustion phenomena in a dispersed phase, whereas the Eulerian approach was applied for the volatile combustion process modeling in a gaseous phase.
Findings
Applying the air- to oxy-combustion technology the temperature in the combustion chamber, decreased for investigated oxidizer compositions. This was caused by the higher heat capacity of flue gases which also influences on the level of the heat flux at the boiler walls. Simulations shows that increasing the O2 concentration to 30 percent of volume base in the oxidizer mixture provided the similar combustion conditions as those for the conventional air firing. Moreover, the evaluated results give a good overview of differences between approaches used for complex swirl burners simulations.
Practical implications
Nowadays, the numerical techniques such as computational fluid dynamic (CFD) can be seen as an useful engineering tool for design and processes optimization purposes. The application of the CFD gives a possibility to predict the combustion phenomena in a large industrial PC boiler and investigate the impact of changing the combustion technology from a conventional air firing to oxy-fuel combustion.
Originality/value
This paper gives good overview on existing technique, approaches used for modeling PC boiler equipped with complex swirl burners. Additionally, the novelty of this work is application of the heat exchanger model for predicting heat loses in convective section of the boiler. This usually is not taken into account during simulations. The reader can also find basic concept of oxy-combustion technology, and their impact on boiler working conditions.
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G. Kersuzan, Nigel Batt, Brian Waterfield, Hamish Law, B. Herod, M.A. Whiteside and Nihal Sinnadurai
The International Electronic Components Show in Paris in November, 1983, provided the occasion for a very successful meeting of ISHM‐France which attracted 170 attendees. The…
Abstract
The International Electronic Components Show in Paris in November, 1983, provided the occasion for a very successful meeting of ISHM‐France which attracted 170 attendees. The following presentations were given:
Bartlomiej Melka, Wojciech P. Adamczyk, Marek Rojczyk, Marcin L. Nowak, Maria Gracka, Andrzej J. Nowak, Adam Golda, Ryszard A. Bialecki and Ziemowit Ostrowski
The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of…
Abstract
Purpose
The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta.
Design/methodology/approach
The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF).
Findings
A model of the blood flow in the arches of the main aorta branches has been presented. The model was built using the multifluid Euler–Euler approach with the interaction between the phases described by the KTGF. The flow and pressure patterns, as well as the volumetric concentration of the blood components, were calculated. The lumped parameter model was implemented to couple the interaction of the computational domain with the remaining portion of the vascular bed.
Originality/value
The multiphase model based on the Euler–Euler approach describing blood flow in the branched large vessel with a three-element Windkessel model in the coarcted geometry was not previously described in the literature.
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Wojciech Szelag, Andrzej Demenko and Lech Nowak
The time‐stepping finite method of transient analysis in permanent magnet synchronous machines has been presented. This method has been used for determining the steady‐state and…
Abstract
The time‐stepping finite method of transient analysis in permanent magnet synchronous machines has been presented. This method has been used for determining the steady‐state and dynamic performance of the permanent magnet self‐starting synchronous motor. The movement of the rotor, the saturation of the ferromagnetic core, the properties of permanent magnet and eddy currents in the solid bars of the cage winding have been taken into account.
Wojciech Chajec, Wieslaw A. Krzymien and Andreas Strohmayer
The separation of energy conversion and propulsor is a promising aspect of hybrid-electric propulsion systems, allowing for increased installation efficiencies and setting the…
Abstract
Purpose
The separation of energy conversion and propulsor is a promising aspect of hybrid-electric propulsion systems, allowing for increased installation efficiencies and setting the basis for distributed propulsion concepts. University of Stuttgart’s Institute of Aircraft Design has a long experience with electrically powered aircraft, starting with Icaré 2, a solar-powered glider flying, since 1996. Icaré 2 recently has been converted to a three-engine motor glider with two battery-powered wing-tip propellers, in addition to the solar-powered main electric motor. This adds propulsion redundancy and will allow analyzing yaw control concepts with differential thrust and the propeller-vortex interaction at the wing-tip. To ensure airworthiness for this design modification, new ground vibration tests (GVTs) and flutter calculations are required. The purpose of this paper is to lay out the atypical approach to test execution due to peculiarities of the Icaré 2 design such as an asymmetrical aileron control system, the long wing span with low frequencies of the first mode and elevated wing tips bending under gravity and thus affecting the accuracy of the wing torsion frequency measurements.
Design/methodology/approach
A flutter analysis based on GVT results is performed for the aircraft in basic configuration and with wing tip propulsors in pusher or tractor configuration. Apart from the measured resonant modes, the aircraft rigid body modes and the control surface mechanism modes are taken into consideration. The flutter calculations are made by a high-speed, low-cost software named JG2 based on the strip theory in aerodynamics and the V-g method of flutter problem solution.
Findings
With the chosen atypical approach to GVT the impact of the suspension on the test results was shown to be minimal. Flutter analysis has proven that the critical flutter speed of Icaré 2 is sufficiently high in all configurations.
Practical implications
The atypical approach to GVT and subsequent flutter analysis have shown that the effects of wing-tip propulsors on aeroelasticity of the high aspect ratio configuration do not negatively affect flutter characteristics. This analysis can serve as a basis for an application for a permit to fly.
Originality/value
The presented methodology is valuable for the flutter assessment of aircraft configurations with atypical aeroelastic characteristics.