Viktor Szente | Budapest University of Technology and Economics (original) (raw)
Papers by Viktor Szente
Most modern airplanes are powered with IC engines because electrical propulsion was not feasible ... more Most modern airplanes are powered with IC engines because electrical propulsion was not feasible at the dawn of powered flight. It became viable only recently due to advancements made on electric propulsion systems. Weight and space are key factors for airplanes. Increasing the power density of the engine can enable the design of more efficient and more powerful planes. One way to achieve this is to increase the power level of the electric motor which also increases the power loss. In this case more efficient cooling is needed to remove the excess heat. The aim of this paper is to determine the optimal cooling solution for the stator of a radial flux permanent magnet (PM) electric motor which is installed in an electric airplane. Computational fluid dynamics (CFD) is used for the comparison of the developed concepts and their sub-concepts. The results are detailed for every initial concept and then the three best designs are chosen for further optimisation. Most modern airplanes are...
In the current study a connected expander – compressor system is investigated. The system is a no... more In the current study a connected expander – compressor system is investigated. The system is a novel development of such systems to extract mechanical energy from low enthalpy sources, e.g. thermal water, geothermal sources. The system consists of an expander in which warm air expands and flows toward a compressor stage. The connection between the devices has a heat exchanger, thus cooled air is introduced to the compressor. After compression the flow exits the compressor at around atmospheric conditions. During the investigation the Computational Fluid Dynamics (CFD) model of this system is built. The heat exchange in the connecting duct is modelled as an idealised heat exchanger with no pressure loss and perfect efficiency. The aim of the investigation is to find out the flow related parameters and efficiency of the whole connected system with the help of CFD simulations
A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, whi... more A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, which is capable for analyzing and predicting the flow characteristics of small electropneumatic (EP) valves within a wide range of pressure ratios in the sonic range. The flow coefficient in the model has been identified on the basis of experiments and was compared with the Perry model. The flow coefficient values have been successfully reproduced by axisymmetric quasi-3D (Q3D) computations using the FLUENT code.
A generally applicable, synthetic simulation model and computational tool has been elaborated for... more A generally applicable, synthetic simulation model and computational tool has been elaborated for dynamic simulation of solenoid valves (SV) applied as control elements in fast-response pneumatic fluid power systems. The SV of case study has been modeled as a system consisting of coupled magnetodynamic and mechanical subsystems. At the present state of investigation, fluid dynamic effects are not considered in the model. The appropriateness of the model has been verified by experimental data. The simulation model resolves the valve body motion and the solenoid current at a high accuracy. It has been pointed out in the concerted numerical and experimental studies that the valve body performs repetitive flexible collision (bouncing) at its opened end-position. Such initial vibrating motion of valve body may affect favorably the SV fluid transmission characteristics, transferring momentum to the fluid in the orifice cross-section. The investigation reveals that the valve body penetrate...
Supersonic flow over a tapered body of revolution has been investigated both experimentally and n... more Supersonic flow over a tapered body of revolution has been investigated both experimentally and numerically. The experimental study consisted of a series of wind tunnel tests on an ogive-cylinder body. Static pressure distributions on the body surfaces at several longitudinal cross sections, as well as the boundary layer profiles at various angles of attack have been measured. Further, the flow around the model was visualized using Schlieren technique. Tests with a natural development of the boundary layer and with tripping were also carried out. All tests were conducted in the trisonic wind tunnel of Qadr Research Center. Our results show that artificial boundary layer tripping has minor effect on the static surface pressure distribution (depending on its diameter and installation location), while the changes in total pressure around the body were significant. Tripping the boundary layer increased its thickness, changed its profile particularly near the body surface. Two oblique shock waves were formed in the front and behind the trip wire. In this study, using multi-block grid, the thin layer Navier-Stokes (TLNS) equations were solved around the above models. Also patched method was used near the interfaces. Good agreements were achieved when the numerical results were compared with the corresponding experimental data.
This paper proposes an alternative method for measuring the flow characteristics of pneumatic flu... more This paper proposes an alternative method for measuring the flow characteristics of pneumatic fluid power elements, which aims to provide a more economical way to assess the flow characteristics. This method can be used effectively in already installed systems, which can be a great help for experts to optimize systems with numerical simulation tools.
Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is... more Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is to ensure a controlled operating pressure modulated at a high accuracy and high temporal resolution. This paper reports a computational case study representing the influence of gas dynamic pipe flow effects on the operation of a pneumatic system to be controlled by means of an EPM. The simulation has been carried out with use of simulation software AMESim version 3.01. Given that no standard gas dynamic pipe model and electro-dynamically-relevant solenoid valve model are included in the present version of the simulation software, such models had to be elaborated by the authors. The simulation studies reveal that the self-developed gas dynamic pipe model resolves properly the wave effects and flow fluctuations expected from a realistic pneumatic pipe performing high velocity flow. The simulation must accurately resolve such phenomena if the computational study aims to provide an aid to t...
Turbocharged engines exhibit the so called turbo lag phenomenon causing a disadvantageous respons... more Turbocharged engines exhibit the so called turbo lag phenomenon causing a disadvantageous response comparing to atmospheric or mechanically supercharged engines. There are many solutions developed to reduce the lag effect although each of them has some disadvantages. This paper investigates a booster module that injects compressed air to increase the response of turbocharged compression ignition engines of commercial vehicles. The investigations applied 3D computational fluid dynamic (CFD) simulations in stationary and transient manner as well. The transient simulations were applied as standalone and coupled calculations to a 1D engine simulation code to capture more accurate boundary conditions (BC). The drawbacks and problems of this new and advanced approach are emphasized in the paper. Due to the deformation of the flow field boundary surface during the dynamic process a deforming mesh method has been applied here. Instant shape of flow field boundary has been obtained by solvin...
A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics ... more A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics of small electro-pneumatic (EP) valves within a wide range of pressure ratio. As a basis for character-ization of flow coefficient, an analytical model has been established for a simplified geometry. This model has been corrected corresponding to more complex valve geometries, utilizing the results of axisymmetric quasi-3D (Q3D) computations using the Computational Fluid Dynamics (CFD) code FLUENT. By this means, a semi-empirical modelling methodology has been elaborated for charac-terization of through-flow behavior of pneumatic valves of various geometries.
Electro-pneumatic (EP) components are frequently used in brake systems of commercial vehicles. Th... more Electro-pneumatic (EP) components are frequently used in brake systems of commercial vehicles. The simulation of EP brake systems is of great importance in order to understand their dynamics for developing a control logic being robust but fulfilling the modern functional demands. On the other hand, the simulation aids the design of EP components being able to execute the commands of a precision control. The paper presents a flexible computational simulation tool being applied in industrial research and development related to complex mechatronics in brake systems for commercial vehicles. The Electric Braking System (EBS) case study presented herein comprises an air supply unit, an EBS modulator, piping, a diaphragm brake chamber, and the connected brake mechanism. The simulation environment is AMESim ® 3.0. Considering the complexity of the EP components and the related phenomena, special models have been elaborated for the solenoid valves, piping, and the diaphragm brake chamber. Th...
Pneumatic Electric Braking Systems (EBS) are frequently used in commercial vehicles. These system... more Pneumatic Electric Braking Systems (EBS) are frequently used in commercial vehicles. These systems are controlled at about 100 Hz, thus the dynamic behaviour of them is essential to know. Since solenoid valves are playing important role in control, the knowledge on the dynamic behaviour of these valves is essential. This paper presents the development of a computer-controlled experimental facility, for investigation of the Cq flow coefficient. This documentation presents the comparison of the experimental methods to international literature and numerical flow simulations.
Periodica Polytechnica Mechanical Engineering, 2003
A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics ... more A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics of small electro-pneumatic (EP) valves within a wide range of pressure ratio. As a basis for characterization of flow coefficient, an analytical model has been established for a simplified geometry. This model has been corrected corresponding to more complex valve geometries, utilizing the results of axisymmetric quasi-3D (Q3D) computations using the Computational Fluid Dynamics (CFD) code FLUENT. By this means, a semi-empirical modelling methodology has been elaborated for characterization of through-flow behavior of pneumatic valves of various geometries.
SUMMARY A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environm... more SUMMARY A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, which is capable of analyzing and predicting the flow characteristics of small electropneumatic (EP) valves within a wide range of pressure ratios. The flow coefficient in the model has been identified on the basis of experiments and was compared with the Perry model. The flow coefficient values have been successfully reproduced by axisymmetric quasi-3D (Q3D) computations using the FLUENT code. A number of different geometries were analyzed to determine the correlation between the geometry and the flow coefficient.
Nowadays, due to the more and more important environmental issues and strict emission regulations... more Nowadays, due to the more and more important environmental issues and strict emission regulations, the electric vehicles are becoming popular and appearing in each type of transport, also in the aircraft industry. In this field, light weight, compact size, high power, and efficiency are the major design aspects. These criteria cause higher power density, thus the losses generated by the active parts are concentrated in a smaller volume. To handle the high thermal load, heat has to be effectively removed. The aim of this article is to improve the aircooling system of a radial flux electric motor with the help of computational fluid dynamics (CFD) simulation. The stator is cooled by a water jacket, and the rotor is cooled by air in the closed housing. Several closed concepts are examined, with the different rotor and housing geometry. During the simulations, motor with a full load at maximal rotating speed is modelled. The results are compared with the base motor in the aspects of the...
Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is... more Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is to ensure a controlled operating pressure modulated at a high accuracy and high temporal resolution. This paper reports a computational case study representing the influence of gas dynamic pipe flow effects on the operation of a pneumatic system to be controlled by means of an EPM. The simulation has been carried out with use of simulation software AMESim version 3.01. Given that no standard gas dynamic pipe model and electro-dynamically-relevant solenoid valve model are included in the present version of the simulation software, such models had to be elaborated by the authors. The simulation studies reveal that the self-developed gas dynamic pipe model resolves properly the wave effects and flow fluctuations expected from a realistic pneumatic pipe performing high velocity flow. The simulation must accurately resolve such phenomena if the computational study aims to provide an aid to t...
Pneumatic circuit protection valves are frequently used in the air supply systems of commercial v... more Pneumatic circuit protection valves are frequently used in the air supply systems of commercial vehicles. This paper presents a flexible computational simulation tool being applied in industrial research and development related to complex mechanical and fluid dynamical aspects in such devices. The numerical model has been created with AMESim, a commercial simulation environment, and then validated by simplified experiments. The comparative numerical and experimental study confirmed that the validated numerical model is able to predict the oscillatory behavior appearing in certain setups, and the system parameter alterations suggested by the simulation successfully eliminated the harmful vibration in the experimental setups as well.
Most modern airplanes are powered with IC engines because electrical propulsion was not feasible ... more Most modern airplanes are powered with IC engines because electrical propulsion was not feasible at the dawn of powered flight. It became viable only recently due to advancements made on electric propulsion systems. Weight and space are key factors for airplanes. Increasing the power density of the engine can enable the design of more efficient and more powerful planes. One way to achieve this is to increase the power level of the electric motor which also increases the power loss. In this case more efficient cooling is needed to remove the excess heat. The aim of this paper is to determine the optimal cooling solution for the stator of a radial flux permanent magnet (PM) electric motor which is installed in an electric airplane. Computational fluid dynamics (CFD) is used for the comparison of the developed concepts and their sub-concepts. The results are detailed for every initial concept and then the three best designs are chosen for further optimisation. Most modern airplanes are...
In the current study a connected expander – compressor system is investigated. The system is a no... more In the current study a connected expander – compressor system is investigated. The system is a novel development of such systems to extract mechanical energy from low enthalpy sources, e.g. thermal water, geothermal sources. The system consists of an expander in which warm air expands and flows toward a compressor stage. The connection between the devices has a heat exchanger, thus cooled air is introduced to the compressor. After compression the flow exits the compressor at around atmospheric conditions. During the investigation the Computational Fluid Dynamics (CFD) model of this system is built. The heat exchange in the connecting duct is modelled as an idealised heat exchanger with no pressure loss and perfect efficiency. The aim of the investigation is to find out the flow related parameters and efficiency of the whole connected system with the help of CFD simulations
A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, whi... more A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, which is capable for analyzing and predicting the flow characteristics of small electropneumatic (EP) valves within a wide range of pressure ratios in the sonic range. The flow coefficient in the model has been identified on the basis of experiments and was compared with the Perry model. The flow coefficient values have been successfully reproduced by axisymmetric quasi-3D (Q3D) computations using the FLUENT code.
A generally applicable, synthetic simulation model and computational tool has been elaborated for... more A generally applicable, synthetic simulation model and computational tool has been elaborated for dynamic simulation of solenoid valves (SV) applied as control elements in fast-response pneumatic fluid power systems. The SV of case study has been modeled as a system consisting of coupled magnetodynamic and mechanical subsystems. At the present state of investigation, fluid dynamic effects are not considered in the model. The appropriateness of the model has been verified by experimental data. The simulation model resolves the valve body motion and the solenoid current at a high accuracy. It has been pointed out in the concerted numerical and experimental studies that the valve body performs repetitive flexible collision (bouncing) at its opened end-position. Such initial vibrating motion of valve body may affect favorably the SV fluid transmission characteristics, transferring momentum to the fluid in the orifice cross-section. The investigation reveals that the valve body penetrate...
Supersonic flow over a tapered body of revolution has been investigated both experimentally and n... more Supersonic flow over a tapered body of revolution has been investigated both experimentally and numerically. The experimental study consisted of a series of wind tunnel tests on an ogive-cylinder body. Static pressure distributions on the body surfaces at several longitudinal cross sections, as well as the boundary layer profiles at various angles of attack have been measured. Further, the flow around the model was visualized using Schlieren technique. Tests with a natural development of the boundary layer and with tripping were also carried out. All tests were conducted in the trisonic wind tunnel of Qadr Research Center. Our results show that artificial boundary layer tripping has minor effect on the static surface pressure distribution (depending on its diameter and installation location), while the changes in total pressure around the body were significant. Tripping the boundary layer increased its thickness, changed its profile particularly near the body surface. Two oblique shock waves were formed in the front and behind the trip wire. In this study, using multi-block grid, the thin layer Navier-Stokes (TLNS) equations were solved around the above models. Also patched method was used near the interfaces. Good agreements were achieved when the numerical results were compared with the corresponding experimental data.
This paper proposes an alternative method for measuring the flow characteristics of pneumatic flu... more This paper proposes an alternative method for measuring the flow characteristics of pneumatic fluid power elements, which aims to provide a more economical way to assess the flow characteristics. This method can be used effectively in already installed systems, which can be a great help for experts to optimize systems with numerical simulation tools.
Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is... more Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is to ensure a controlled operating pressure modulated at a high accuracy and high temporal resolution. This paper reports a computational case study representing the influence of gas dynamic pipe flow effects on the operation of a pneumatic system to be controlled by means of an EPM. The simulation has been carried out with use of simulation software AMESim version 3.01. Given that no standard gas dynamic pipe model and electro-dynamically-relevant solenoid valve model are included in the present version of the simulation software, such models had to be elaborated by the authors. The simulation studies reveal that the self-developed gas dynamic pipe model resolves properly the wave effects and flow fluctuations expected from a realistic pneumatic pipe performing high velocity flow. The simulation must accurately resolve such phenomena if the computational study aims to provide an aid to t...
Turbocharged engines exhibit the so called turbo lag phenomenon causing a disadvantageous respons... more Turbocharged engines exhibit the so called turbo lag phenomenon causing a disadvantageous response comparing to atmospheric or mechanically supercharged engines. There are many solutions developed to reduce the lag effect although each of them has some disadvantages. This paper investigates a booster module that injects compressed air to increase the response of turbocharged compression ignition engines of commercial vehicles. The investigations applied 3D computational fluid dynamic (CFD) simulations in stationary and transient manner as well. The transient simulations were applied as standalone and coupled calculations to a 1D engine simulation code to capture more accurate boundary conditions (BC). The drawbacks and problems of this new and advanced approach are emphasized in the paper. Due to the deformation of the flow field boundary surface during the dynamic process a deforming mesh method has been applied here. Instant shape of flow field boundary has been obtained by solvin...
A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics ... more A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics of small electro-pneumatic (EP) valves within a wide range of pressure ratio. As a basis for character-ization of flow coefficient, an analytical model has been established for a simplified geometry. This model has been corrected corresponding to more complex valve geometries, utilizing the results of axisymmetric quasi-3D (Q3D) computations using the Computational Fluid Dynamics (CFD) code FLUENT. By this means, a semi-empirical modelling methodology has been elaborated for charac-terization of through-flow behavior of pneumatic valves of various geometries.
Electro-pneumatic (EP) components are frequently used in brake systems of commercial vehicles. Th... more Electro-pneumatic (EP) components are frequently used in brake systems of commercial vehicles. The simulation of EP brake systems is of great importance in order to understand their dynamics for developing a control logic being robust but fulfilling the modern functional demands. On the other hand, the simulation aids the design of EP components being able to execute the commands of a precision control. The paper presents a flexible computational simulation tool being applied in industrial research and development related to complex mechatronics in brake systems for commercial vehicles. The Electric Braking System (EBS) case study presented herein comprises an air supply unit, an EBS modulator, piping, a diaphragm brake chamber, and the connected brake mechanism. The simulation environment is AMESim ® 3.0. Considering the complexity of the EP components and the related phenomena, special models have been elaborated for the solenoid valves, piping, and the diaphragm brake chamber. Th...
Pneumatic Electric Braking Systems (EBS) are frequently used in commercial vehicles. These system... more Pneumatic Electric Braking Systems (EBS) are frequently used in commercial vehicles. These systems are controlled at about 100 Hz, thus the dynamic behaviour of them is essential to know. Since solenoid valves are playing important role in control, the knowledge on the dynamic behaviour of these valves is essential. This paper presents the development of a computer-controlled experimental facility, for investigation of the Cq flow coefficient. This documentation presents the comparison of the experimental methods to international literature and numerical flow simulations.
Periodica Polytechnica Mechanical Engineering, 2003
A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics ... more A semi-empirical model has been elaborated for analyzing and predicting the flow characteristics of small electro-pneumatic (EP) valves within a wide range of pressure ratio. As a basis for characterization of flow coefficient, an analytical model has been established for a simplified geometry. This model has been corrected corresponding to more complex valve geometries, utilizing the results of axisymmetric quasi-3D (Q3D) computations using the Computational Fluid Dynamics (CFD) code FLUENT. By this means, a semi-empirical modelling methodology has been elaborated for characterization of through-flow behavior of pneumatic valves of various geometries.
SUMMARY A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environm... more SUMMARY A simplified one-dimensional (1D) simulation model has been elaborated in AMESim environment, which is capable of analyzing and predicting the flow characteristics of small electropneumatic (EP) valves within a wide range of pressure ratios. The flow coefficient in the model has been identified on the basis of experiments and was compared with the Perry model. The flow coefficient values have been successfully reproduced by axisymmetric quasi-3D (Q3D) computations using the FLUENT code. A number of different geometries were analyzed to determine the correlation between the geometry and the flow coefficient.
Nowadays, due to the more and more important environmental issues and strict emission regulations... more Nowadays, due to the more and more important environmental issues and strict emission regulations, the electric vehicles are becoming popular and appearing in each type of transport, also in the aircraft industry. In this field, light weight, compact size, high power, and efficiency are the major design aspects. These criteria cause higher power density, thus the losses generated by the active parts are concentrated in a smaller volume. To handle the high thermal load, heat has to be effectively removed. The aim of this article is to improve the aircooling system of a radial flux electric motor with the help of computational fluid dynamics (CFD) simulation. The stator is cooled by a water jacket, and the rotor is cooled by air in the closed housing. Several closed concepts are examined, with the different rotor and housing geometry. During the simulations, motor with a full load at maximal rotating speed is modelled. The results are compared with the base motor in the aspects of the...
Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is... more Electro-pneumatic modulators (EPMs) are widely used in controlled pneumatic systems. Their aim is to ensure a controlled operating pressure modulated at a high accuracy and high temporal resolution. This paper reports a computational case study representing the influence of gas dynamic pipe flow effects on the operation of a pneumatic system to be controlled by means of an EPM. The simulation has been carried out with use of simulation software AMESim version 3.01. Given that no standard gas dynamic pipe model and electro-dynamically-relevant solenoid valve model are included in the present version of the simulation software, such models had to be elaborated by the authors. The simulation studies reveal that the self-developed gas dynamic pipe model resolves properly the wave effects and flow fluctuations expected from a realistic pneumatic pipe performing high velocity flow. The simulation must accurately resolve such phenomena if the computational study aims to provide an aid to t...
Pneumatic circuit protection valves are frequently used in the air supply systems of commercial v... more Pneumatic circuit protection valves are frequently used in the air supply systems of commercial vehicles. This paper presents a flexible computational simulation tool being applied in industrial research and development related to complex mechanical and fluid dynamical aspects in such devices. The numerical model has been created with AMESim, a commercial simulation environment, and then validated by simplified experiments. The comparative numerical and experimental study confirmed that the validated numerical model is able to predict the oscillatory behavior appearing in certain setups, and the system parameter alterations suggested by the simulation successfully eliminated the harmful vibration in the experimental setups as well.