Csaba Hetyei | Óbuda University (original) (raw)

Papers by Csaba Hetyei

Biztonságtudományi Szemle, Feb 21, 2021

Throughout human history, epidemics have occurred in many cases, which have also affected society... more Throughout human history, epidemics have occurred in many cases, which have also affected society and the economy. At the end of 2019, the COVID-19 or SARS-CoV-19 virus appeared and caused a pandemic in 2020, which resulted in unprecedented changes both globally and individually. In our article, we were analysing the spreading and evolution of a violent expiratory event (sneeze, cough) in a subway car. In our research, we followed a sneezed/coughed air using a computational fluid dynamics (CFD) software, thus it became visible in which directions the coughed volume spreads. Using our results, passengers' sense of security can be increased, therefore if someone sneezes in the studied subway car, the passengers can decide that the sneezing is a real risk of infection for them or not.

Napjaink egyik legnépszerűbb háztartási fűtőteste az ún. lapradiátor, melynek hatásfoka jobb, min... more Napjaink egyik legnépszerűbb háztartási fűtőteste az ún. lapradiátor, melynek hatásfoka jobb, mint sok más típusé. Célszerű azonban az egyre nagyobb hangsúlyt kapott energiamegtakarítás szemszögéből is megvizsgálni ezt az eszközt, azt, hogy miképpen tudjuk tovább javítani a hőleadás hatásfokát, hatásosságát. A hatásosság javítása a mai kiforrott technológiák és konstrukciók mellett meglehetősen nehéz feladat. Egy lehetséges megoldás a radiátorokon átáramló levegő sebességének növelése külső ventilátorok segítségével. A módszer előnye, hogy minden radiátorra fel lehet szerelni külső ventilátorokat és nem kell módosítani a fűtési rendszert. Fent leírtak alapján megépített fűtési rendszer vizsgálatáról számolunk be ebben a munkában. Egy új, gyári lapradiátort szereltünk be egy üres terembe, ahol teljes fűtőrendszert állítottunk össze. A lapradiátort felszereltük ventilátorokkal, amelyeket külön szívó és külön nyomó üzemben is működtettünk. Megvizsgáltuk a ventilátorok hatását különböző...

Bánki Közlemények (Bánki Reports), Jun 12, 2019

Összefoglalás-Napjainkban jelentkező egyre nagyobb energiaigény miatt, mindinkább előtérbe kerüln... more Összefoglalás-Napjainkban jelentkező egyre nagyobb energiaigény miatt, mindinkább előtérbe kerülnek a megújuló energiaforrások és hasznosításuk. Cikkünkben kisteljesítményű szélkerekek típusait és hasznosításukat tekintjük át épített környezetünkben. Majd egy 10 emeletes épület tetején kialakuló áramlási képet vizsgálunk meg, végestérfogat alapú áramlástani szimulációs módszerrel. Ezt követően előterelőkkel az áramlási képet úgy módosítjuk, hogy az optimálisabb legyen a szélturbina telepítéshez.

Biztonságtudományi Szemle, Mar 17, 2021

Acta Polytechnica, 2021

General energy demand is continuously increasing, thus the energy generating assets need to be op... more General energy demand is continuously increasing, thus the energy generating assets need to be optimised for higher efficiency. Wind turbines are no exception. Their maximum efficiency can be determined on a theoretical basis. The limit is approached by researches day by day, utilizing the latest developments in airfoil design, blade structure and new and improved ideas in conventional and unconventional wind turbine layouts. In this paper, we are reviewing the conventional and unconventional wind turbines and their place in smart cities. Then, an unconventional wind turbine design, the CO-DRWT (counter-rotating dual rotor wind turbine) is analysed with a CFD (computational fluid dynamics) code, varying the axial and radial distances between the two turbines. After the simulations, the power coefficients for the different turbine configurations is calculated. At the end of this paper, the simulations results are summarized and consequences are drawn for the CO-DRWT layouts.

Modern military doctrines are increasingly emphasising the ability to autonomously use the capabi... more Modern military doctrines are increasingly emphasising the ability to autonomously use the capabilities supported by military infrastructure networks. Therefore, in the theatres of military operations, the temporary facilities should provide their own increasing energy needs. Military energetic engineers are increasingly exploring the technical solutions of energy production in camp environments. In this article, not taking into consideration traditional fossil fuel technology, we concentrate on the renewable energy sources, especially the wind turbines. The wind energy utilisation can be a good solution for mobility and environmental aspects: released harmful material and noise level are lower than in the case of industrial generators. However, the technical safety of wind power plants requires improvement of human, environmental and fire safety. In this article, we will scope the wind turbine failures and highlight the fire accidents and the protection against them.

A napjainkban jelentkező egyre nagyobb energiaigeny miatt, mindinkabb előterbe kerulnek a megujul... more A napjainkban jelentkező egyre nagyobb energiaigeny miatt, mindinkabb előterbe kerulnek a megujulo energiaforrasok. Cikkunkben a vizszintes tengelyű szelturbinak lapatozasanak numerikus aramlastani szoftverrel tortenő vizsgalatat mutatjuk be. Szimulacioink soran a szelkereken ebredő nyomatekot a lapat lapatszog-szabalyzas (Pitch Control) fuggvenyeben elemeztuk.

Absztrakt The customers growing demand for energy utilization and the need for green and sustaina... more Absztrakt The customers growing demand for energy utilization and the need for green and sustainable energy have changed our energy security. Changes in the energy mix have become necessary by the developments and improvements of the energy producers and the need by the population for an energyefficient and sustainable future, thus today’s expectation in this engineering field is to design more efficiently and sustainably than ever before in an economically efficient way. In our article, we are reviewing the conventional and the newly spreading non-conventional wind turbines and they place of use. After this overview, we are presenting the foundation of wind turbines efficiency and its power coefficient. Later, we are introducing a Computational Fluid Dynamics (CFD) simulation for a CounterRotating Dual-Rotor Wind Turbine (CODRWT) with different rotor sizes. After the simulation, we are examining the overall power coefficient of turbines and its change by the turbine size. Energiabi...

Interdisciplinary Description of Complex Systems, 2020

General energy demand is continuously increasing due to the fact that wind turbines and other ren... more General energy demand is continuously increasing due to the fact that wind turbines and other renewable energy sources have begun to appear in previously unexplored areas, such as on the roofs of buildings. In view of this demand, a new type of wind turbines described in this article could become one of the energy generating tools in a smart grid system. In this article, first conventional and unconventional wind turbines are reviewed with respect to efficiency. Then a Counter Rotating Dual Rotor Wind Turbine (CO-DRWT) construction is analysed with Computational Fluid Dynamics (CFD) codes considering a fixed radial and a variable axial distance. In the analysis, power coefficients were calculated for different configurations. It was found that in case of the dual rotor wind turbine, the optimal axial distance for half diameter radial shift was in the range of 0,2-0,25 diameter.

Progress in Agricultural Engineering Sciences, 2020

The engineering application's design process starts with a concept, based on our theoretical ... more The engineering application's design process starts with a concept, based on our theoretical knowledge and continues with a numerical simulation. In our paper, we review the finite volume method (FVM) which is used generally for heat and fluid dynamic simulations.We compare three different computational fluid dynamics (CFD) software (based in the fine volume method) for validating a NACA airfoil, which can be used for example in the aerospace industry for an airplane's wing profile, and it can be used for example in the renewable industry for a wind turbine's blade or a water turbine's impeller profile. At the end of this paper, the result of our simulations will be compared with a validation case and the difference between the CFD software and the measured data will be presented.

Műszaki Tudományos Közlemények, 2019

Due to the current increase in energy demand, renewable energy sources and their utilization have... more Due to the current increase in energy demand, renewable energy sources and their utilization have become a priority. Thanks to the Smart Grid, which is currently under development, and with the help of the evolving technologies, we are trying to extract more and more energy from sources that we couldn’t exploit before or which weren’t economically viable. In this article, we examine the airflow field for a theoretical warehouse building, dependent on roof inclination angle. The purpose of the analysis was to select the optimal angle under which a roof mounted horizontal axis wind turbine (HAWT) could perform efficiently.

Műszaki Tudományos Közlemények, 2019

Interdisciplinary Description of Complex Systems, Sep 2020

General energy demand is continuously increasing due to the fact that wind turbines and other ren... more General energy demand is continuously increasing due to the fact that wind turbines and other renewable energy sources have begun to appear in previously unexplored areas, such as on the roofs of buildings. In view of this demand, a new type of wind turbines described in this article could become one of the energy generating tools in a smart grid system. In this article, first conventional and unconventional wind turbines are reviewed with respect to efficiency. Then a Counter Rotating Dual Rotor Wind Turbine (CO-DRWT) construction is analysed with Computational Fluid Dynamics (CFD) codes considering a fixed radial and a variable axial distance. In the analysis, power coefficients were calculated for different configurations. It was found that in case of the dual rotor wind turbine, the optimal axial distance for half diameter radial shift was in the range of 0,2-0,25 diameter.

Műszaki Tudományos Közlemények, Sep 2019

Due to the current increase in energy demand, renewable energy sources and their utilization have... more Due to the current increase in energy demand, renewable energy sources and their utilization have become a priority. Thanks to the Smart Grid, which is currently under development, and with the help of the evolving technologies, we are trying to extract more and more energy from sources that we couldn’t exploit before or which weren’t economically viable. In this article, we examine the airflow field for a theoretical warehouse building, dependent on roof inclination angle. The purpose of the analysis was to select the optimal angle under which a roof mounted horizontal axis wind turbine (HAWT) could perform efficiently.

Biztonságtudományi Szemle, Feb 21, 2021

Throughout human history, epidemics have occurred in many cases, which have also affected society... more Throughout human history, epidemics have occurred in many cases, which have also affected society and the economy. At the end of 2019, the COVID-19 or SARS-CoV-19 virus appeared and caused a pandemic in 2020, which resulted in unprecedented changes both globally and individually. In our article, we were analysing the spreading and evolution of a violent expiratory event (sneeze, cough) in a subway car. In our research, we followed a sneezed/coughed air using a computational fluid dynamics (CFD) software, thus it became visible in which directions the coughed volume spreads. Using our results, passengers' sense of security can be increased, therefore if someone sneezes in the studied subway car, the passengers can decide that the sneezing is a real risk of infection for them or not.

Napjaink egyik legnépszerűbb háztartási fűtőteste az ún. lapradiátor, melynek hatásfoka jobb, min... more Napjaink egyik legnépszerűbb háztartási fűtőteste az ún. lapradiátor, melynek hatásfoka jobb, mint sok más típusé. Célszerű azonban az egyre nagyobb hangsúlyt kapott energiamegtakarítás szemszögéből is megvizsgálni ezt az eszközt, azt, hogy miképpen tudjuk tovább javítani a hőleadás hatásfokát, hatásosságát. A hatásosság javítása a mai kiforrott technológiák és konstrukciók mellett meglehetősen nehéz feladat. Egy lehetséges megoldás a radiátorokon átáramló levegő sebességének növelése külső ventilátorok segítségével. A módszer előnye, hogy minden radiátorra fel lehet szerelni külső ventilátorokat és nem kell módosítani a fűtési rendszert. Fent leírtak alapján megépített fűtési rendszer vizsgálatáról számolunk be ebben a munkában. Egy új, gyári lapradiátort szereltünk be egy üres terembe, ahol teljes fűtőrendszert állítottunk össze. A lapradiátort felszereltük ventilátorokkal, amelyeket külön szívó és külön nyomó üzemben is működtettünk. Megvizsgáltuk a ventilátorok hatását különböző...

Bánki Közlemények (Bánki Reports), Jun 12, 2019

Összefoglalás-Napjainkban jelentkező egyre nagyobb energiaigény miatt, mindinkább előtérbe kerüln... more Összefoglalás-Napjainkban jelentkező egyre nagyobb energiaigény miatt, mindinkább előtérbe kerülnek a megújuló energiaforrások és hasznosításuk. Cikkünkben kisteljesítményű szélkerekek típusait és hasznosításukat tekintjük át épített környezetünkben. Majd egy 10 emeletes épület tetején kialakuló áramlási képet vizsgálunk meg, végestérfogat alapú áramlástani szimulációs módszerrel. Ezt követően előterelőkkel az áramlási képet úgy módosítjuk, hogy az optimálisabb legyen a szélturbina telepítéshez.

Biztonságtudományi Szemle, Mar 17, 2021

Acta Polytechnica, 2021

General energy demand is continuously increasing, thus the energy generating assets need to be op... more General energy demand is continuously increasing, thus the energy generating assets need to be optimised for higher efficiency. Wind turbines are no exception. Their maximum efficiency can be determined on a theoretical basis. The limit is approached by researches day by day, utilizing the latest developments in airfoil design, blade structure and new and improved ideas in conventional and unconventional wind turbine layouts. In this paper, we are reviewing the conventional and unconventional wind turbines and their place in smart cities. Then, an unconventional wind turbine design, the CO-DRWT (counter-rotating dual rotor wind turbine) is analysed with a CFD (computational fluid dynamics) code, varying the axial and radial distances between the two turbines. After the simulations, the power coefficients for the different turbine configurations is calculated. At the end of this paper, the simulations results are summarized and consequences are drawn for the CO-DRWT layouts.

Modern military doctrines are increasingly emphasising the ability to autonomously use the capabi... more Modern military doctrines are increasingly emphasising the ability to autonomously use the capabilities supported by military infrastructure networks. Therefore, in the theatres of military operations, the temporary facilities should provide their own increasing energy needs. Military energetic engineers are increasingly exploring the technical solutions of energy production in camp environments. In this article, not taking into consideration traditional fossil fuel technology, we concentrate on the renewable energy sources, especially the wind turbines. The wind energy utilisation can be a good solution for mobility and environmental aspects: released harmful material and noise level are lower than in the case of industrial generators. However, the technical safety of wind power plants requires improvement of human, environmental and fire safety. In this article, we will scope the wind turbine failures and highlight the fire accidents and the protection against them.

A napjainkban jelentkező egyre nagyobb energiaigeny miatt, mindinkabb előterbe kerulnek a megujul... more A napjainkban jelentkező egyre nagyobb energiaigeny miatt, mindinkabb előterbe kerulnek a megujulo energiaforrasok. Cikkunkben a vizszintes tengelyű szelturbinak lapatozasanak numerikus aramlastani szoftverrel tortenő vizsgalatat mutatjuk be. Szimulacioink soran a szelkereken ebredő nyomatekot a lapat lapatszog-szabalyzas (Pitch Control) fuggvenyeben elemeztuk.

Absztrakt The customers growing demand for energy utilization and the need for green and sustaina... more Absztrakt The customers growing demand for energy utilization and the need for green and sustainable energy have changed our energy security. Changes in the energy mix have become necessary by the developments and improvements of the energy producers and the need by the population for an energyefficient and sustainable future, thus today’s expectation in this engineering field is to design more efficiently and sustainably than ever before in an economically efficient way. In our article, we are reviewing the conventional and the newly spreading non-conventional wind turbines and they place of use. After this overview, we are presenting the foundation of wind turbines efficiency and its power coefficient. Later, we are introducing a Computational Fluid Dynamics (CFD) simulation for a CounterRotating Dual-Rotor Wind Turbine (CODRWT) with different rotor sizes. After the simulation, we are examining the overall power coefficient of turbines and its change by the turbine size. Energiabi...

Interdisciplinary Description of Complex Systems, 2020

General energy demand is continuously increasing due to the fact that wind turbines and other ren... more General energy demand is continuously increasing due to the fact that wind turbines and other renewable energy sources have begun to appear in previously unexplored areas, such as on the roofs of buildings. In view of this demand, a new type of wind turbines described in this article could become one of the energy generating tools in a smart grid system. In this article, first conventional and unconventional wind turbines are reviewed with respect to efficiency. Then a Counter Rotating Dual Rotor Wind Turbine (CO-DRWT) construction is analysed with Computational Fluid Dynamics (CFD) codes considering a fixed radial and a variable axial distance. In the analysis, power coefficients were calculated for different configurations. It was found that in case of the dual rotor wind turbine, the optimal axial distance for half diameter radial shift was in the range of 0,2-0,25 diameter.

Progress in Agricultural Engineering Sciences, 2020

The engineering application's design process starts with a concept, based on our theoretical ... more The engineering application's design process starts with a concept, based on our theoretical knowledge and continues with a numerical simulation. In our paper, we review the finite volume method (FVM) which is used generally for heat and fluid dynamic simulations.We compare three different computational fluid dynamics (CFD) software (based in the fine volume method) for validating a NACA airfoil, which can be used for example in the aerospace industry for an airplane's wing profile, and it can be used for example in the renewable industry for a wind turbine's blade or a water turbine's impeller profile. At the end of this paper, the result of our simulations will be compared with a validation case and the difference between the CFD software and the measured data will be presented.

Műszaki Tudományos Közlemények, 2019

Due to the current increase in energy demand, renewable energy sources and their utilization have... more Due to the current increase in energy demand, renewable energy sources and their utilization have become a priority. Thanks to the Smart Grid, which is currently under development, and with the help of the evolving technologies, we are trying to extract more and more energy from sources that we couldn’t exploit before or which weren’t economically viable. In this article, we examine the airflow field for a theoretical warehouse building, dependent on roof inclination angle. The purpose of the analysis was to select the optimal angle under which a roof mounted horizontal axis wind turbine (HAWT) could perform efficiently.

Műszaki Tudományos Közlemények, 2019

Interdisciplinary Description of Complex Systems, Sep 2020

General energy demand is continuously increasing due to the fact that wind turbines and other ren... more General energy demand is continuously increasing due to the fact that wind turbines and other renewable energy sources have begun to appear in previously unexplored areas, such as on the roofs of buildings. In view of this demand, a new type of wind turbines described in this article could become one of the energy generating tools in a smart grid system. In this article, first conventional and unconventional wind turbines are reviewed with respect to efficiency. Then a Counter Rotating Dual Rotor Wind Turbine (CO-DRWT) construction is analysed with Computational Fluid Dynamics (CFD) codes considering a fixed radial and a variable axial distance. In the analysis, power coefficients were calculated for different configurations. It was found that in case of the dual rotor wind turbine, the optimal axial distance for half diameter radial shift was in the range of 0,2-0,25 diameter.

Műszaki Tudományos Közlemények, Sep 2019

Due to the current increase in energy demand, renewable energy sources and their utilization have... more Due to the current increase in energy demand, renewable energy sources and their utilization have become a priority. Thanks to the Smart Grid, which is currently under development, and with the help of the evolving technologies, we are trying to extract more and more energy from sources that we couldn’t exploit before or which weren’t economically viable. In this article, we examine the airflow field for a theoretical warehouse building, dependent on roof inclination angle. The purpose of the analysis was to select the optimal angle under which a roof mounted horizontal axis wind turbine (HAWT) could perform efficiently.