ABSTRACT The aim of this work is to estimate the losses in the steam flow through the LP steam tu... more ABSTRACT The aim of this work is to estimate the losses in the steam flow through the LP steam turbine rotor and the whole stage. For steam flow two types of losses take place, aerodynamic (profile, secondary flow, leakage) and thermodynamic (due to the heat addition caused by condensation). Presented numerical results are split into two groups. In the first part of this work the comparison of the three different calculation methods of steam flow is carried out. To this end the geometry of LP steam turbine last rotor is chosen. The first method is a Streamline Curvature Method (SCM) used on the meridional plane with losses correlations, and the next two methods, commercial and an in-house CFD codes, solve the Reynolds averaged Navier-Stokes equations for a 3-D flow. Below the saturation line the first two codes model equilibrium steam properties, and the last one models non-equilibrium steam properties. Then for the geometry of the penultimate stage, with the use of an in-house CFD code, the comparison of the different types of condensation models on the losses prediction is examined.
In turbomachinery, an influence of a tip-leakage flow on overall blade loss is crucial and its re... more In turbomachinery, an influence of a tip-leakage flow on overall blade loss is crucial and its reduction is still worth striving for. In this paper a numerical analysis of the flow in tip seal of high-rotating gas turbine engine has been made. This analysis is a part of experimental research for testing the commercially used different tip seals solutions. Described test rig is predicted to be an universal tool for developing and examining different configurations of turbine blade tips. Presented numerical analysis is used to predict physical phenomena that may affect the rotor blade performance. In the numerical investigation the commercial Ansys CFX software was employed. The most important parameters were: mass flow rate at the inlet and outlet of the test bench, pressure and velocity distribution and the air temperature growth above the rotor. Also, an influence of test rig inlet and outlet geometry on flow uniformity was investigated. During the analysis the attention was focused also on minimizing the turbulence intensity in outlet area, that could cause significant difficulties in flow and stable work of the machine-generated eddies contributes to lower the mass flow rate.
Atmospheric air is a commonly used working fluid in turbomachinery. The air typically contains a ... more Atmospheric air is a commonly used working fluid in turbomachinery. The air typically contains a certain amount of suspended solid particles, as well as water in the form of vapor or droplets. In the current paper, we focus on the numerical modeling of humid air transonic flow in turbomachinery. In this paper we demonstrate a rarely considered, but as presented herein important influence of air humidity, pollution and liquid water content on the performance of the first stage of the gas turbine compressor and turbofan engine fan (NASA rotors 37 and 67). We also discuss the impact of the interfacial heat transfer associated with steam condensation or water evaporation on the distribution of stagnation parameters at the rotor outlet, the rotor performance, and flow conditions, as well as losses. Results demonstrate the impact of the number of pollution particles and water droplets on the compression process in the analyzed rotors, especially on the Mach number distribution in the blad...
The supersonic nozzle is very often used in many technical applications, such as fluid-flow machi... more The supersonic nozzle is very often used in many technical applications, such as fluid-flow machines or devices. If the medium flowing through a supersonic nozzle is a moist gas, moist air or wet steam, non-equilibrium condensation must occur. Such mediums usually contain impurities which affect the condensation phenomenon. The main purpose of this research is a numerical study on the effect of the content of impurities in steam on the non-equilibrium condensation phenomenon. In order to achieve this purpose, salt (NaCl) is used. Sodium chloride (NaCl) is a very common steam impurity. It may occur in a soluble or crystal form. Different concentrations of salt are considered as the input quantity. The results show that the process of steam condensation on salt particles has a significant impact on two-phase variables and flow parameters. In the presence of salt, steam condensation starts whenever the supersaturation ratio is above one. Latent heat of the condensation changes the flow pattern and reduces the nucleation rate and water droplet production. The presence of 10 15 particles of salt reduces the outlet average liquid mass fraction and entropy generation by 14.5 % and 15.2 % respectively. The research results prove that steam impurities have a significant impact on non-equilibrium condensation.
This article deals with the turbulent transition phenomenon modelling and its influence on heat t... more This article deals with the turbulent transition phenomenon modelling and its influence on heat transfer. The purpose of the analyses was to verify the transition modelling implemented in the ANSYS CFX 11 commercial code for popular test cases (low flow speed) described in literature, and then use it for verification of the in-house CFD code (created for compressible flows). The in-house CFD code has been extended lately for the Conjugate Heat Transfer modelling (CHT) as well, taking into account important flow effects, especially the turbulent transition. A Wilcox k-ω turbulence model with the Low-Reynolds modification was used in the in-house code. The calculations in ANSYS CFX were made using an SST turbulence model and a γ-Θ transition model. A fully turbulent flow was modelled by means of both codes, and the results were compared with the available experimental data. Then, the turbulent transition for several test cases was analysed with ANSYS CFX. Afterwards, the in-house CFD ...
This article deals with the turbulent transition phenomenon modelling and its influence on heat t... more This article deals with the turbulent transition phenomenon modelling and its influence on heat transfer. The purpose of the analyses was to verify the transition modelling implemented in the ANSYS CFX 11 commercial code for popular test cases (low flow speed) described in literature, and then use it for verification of the in-house CFD code (created for compressible flows). The in-house CFD code has been extended lately for the Conjugate Heat Transfer modelling (CHT) as well, taking into account important flow effects, especially the turbulent transition. A Wilcox k-ω turbulence model with the Low-Reynolds modification was used in the in-house code. The calculations in ANSYS CFX were made using an SST turbulence model and a γ-Θ transition model. A fully turbulent flow was modelled by means of both codes, and the results were compared with the available experimental data. Then, the turbulent transition for several test cases was analysed with ANSYS CFX. Afterwards, the in-house CFD ...
In the Institute of Power Engineering and Turbomachinery of The Silesian University of Technology... more In the Institute of Power Engineering and Turbomachinery of The Silesian University of Technology the experimental research have been performed from many years now. To this end a mini steam power station located in Machinery Hall is used. It is unique non-commercial installation of such kind in Europe, consisting of a steam boiler, steam turbine with condenser, electric generator, cooling tower and tunnel to test the wet steam flows. In this paper has been presented purpose and construction of wet steam tunnel and plans for its use. In the present state of this tunnel is an interesting research installation for the analysis of many problems of flow.
In steam condensing turbines of a large output the low-pressure stages operating in wet steam reg... more In steam condensing turbines of a large output the low-pressure stages operating in wet steam regime produce over 10% total output capacity. Their efficiency is significantly lower than the efficiency of the stages working in superheated steam regime. In the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology there is an experimental facility dedicated to the wet steam flow investigation through the nozzles and linear cascades, especially to the identification of the both aerodynamic and thermodynamic losses. This work includes a description of the losses definitions using in an analysis of the flow efficiency of the low-pressure steam stages. There will be presented a method for losses analysis in the wet steam transonic flow by means of an existing in the Institute steam facility.
The present paper describes an experimental and numerical study of steam condensing flow in a lin... more The present paper describes an experimental and numerical study of steam condensing flow in a linear cascade of turbine stator blades. The experimental research was performed on the facility of a small scale steam power plant located at Silesian University of Technology in Gliwice. The test rig of the facility allows us to perform the tests of steam transonic flows for the conditions corresponding to these which prevail in the low-pressure (LP) condensing steam turbine stages. The experimental data of steam condensing flow through the blade-to-blade stator channel were compared with numerical results obtained using the in-house CFD numerical code TraCoFlow. Obtained results confirmed a good quality of the performed experiment and numerical calculations.
The power technologies with steam turbines generate more than 60% of the electricity for the enti... more The power technologies with steam turbines generate more than 60% of the electricity for the entire world and the world electricity generation is projected to become about 1.5 times as large as the current demand in 2013 until 2035. Consequently, the development and practical implementation of the efficiency enhancement technology of steam turbines for power generation should be driven to supply the necessary electricity while restraining and reducing global greenhouse gas emissions. The wet steam constitutes a serious problem in condensing steam turbines, contributing to the additional losses generation and erosion processes. In order to reduce this type of losses the better understanding of the phenomena undergoing in wet steam transonic flows is necessary. In spite of many numerical and experimental research in this field many issues are still not recognized and not clearly explained. The presented work concerns a novel experimental research comprising the new and more effective ...
Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flow w... more Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flow were carried out in linear blade cascade. The linear cascade consists of the stator blades of the low pressure steam turbine last stage. The applied experimental test section is a part of a small scale steam power plant located at Silesian University of Technology. The steam parameters at the test section inlet correspond to the real conditions in low pressure part of 200MWe steam turbine. The static pressure measurements on the blade surface as well as the Schlieren pictures were used to assess the flow field in linear cascade of the steam turbine stator blades. The capabilities of used measurement techniques were estimated for gaining knowledge of condensation process in linear blade cascade.
The goal of the presented work is an optimization of the geometrical configuration of the tip sea... more The goal of the presented work is an optimization of the geometrical configuration of the tip seal with a honeycomb land, to reduce the leakage flow in the counter-rotating LP turbine of a contra-rotating open rotor aero-engine. This goal was achieved with the use of the Ansys-CFX commercial code and an in-house optimization procedure. The detailed studies including the mesh influence, the stages of the computational domain simplification, and geometry variants are discussed. The optimization process is based on a single objective genetic algorithm (SOGA). The automatic grid generation process and the CFD calculations are based on scripts prepared under the Ansys-ICEM and Ansys-CFX software. The whole procedure is written in the Visual Basic for Applications language (VBA), which allows a direct access to the CAD software with the use of macros and allows a proper connection between the CAD environment and the CFD software. The described algorithm allows parallel computing. In addit...
Przemysł energetyczny na całym świecie wyznaczył sobie ambitny cel: przesunięcie granicy sprawnoś... more Przemysł energetyczny na całym świecie wyznaczył sobie ambitny cel: przesunięcie granicy sprawności netto bloków węglowych z obecnej wartości referencyjnej 46% do 50% i wyższej. Przekroczenie symbolicznej bariery 50% wymaga znaczących zmian technologicznych, a w szczególności ogromnego postępu w dziedzinie inżynierii materiałowej. Ogromne koszty związane z zastosowaniem stopów niklowych w podstawowych elementach bloku parowego zmusiły do dużego kroku w obszarze górnych parametrów termodynamicznych obiegu parowego i rozpoczęcia w technologii elektrowni parowych następnej fazy rozwojowej – zaawansowanych parametrów ultra-nadkrytycznych (A-USC – advanced ultra-supercritical). Za cel rozwoju energetyki zawodowej w Europie przyjęto osiągnięcie temperatury pary wynoszącej 700°C i ciśnienia 35 MPa, co być może pozwoli na osiągnięcie sprawności bloku netto 50%. Osiągnięcie tak wysokich parametrów pary w blokach węglowych wymaga zastosowania nowych materiałów konstrukcyjnych do budowy kotła ...
The presented paper shows our first step into the numerical modelling of the thermoacoustic pheno... more The presented paper shows our first step into the numerical modelling of the thermoacoustic phenomenon. The thermoacoustic effect has a great application potential, for instance, in thermoacoustic engines or thermoacoustic mixture separation. These two applications are in the centre of our interest. The modelling of thermoacoustic effects consists in a solution of transport equations, mass, momentum and energy, to identify the influence of heat transfer on the sonic oscillation and vice versa. The numerical modelling of such sensitive and sophisticated phenomena requires a high quality numerical tool. The commercial CFD code ANSYS CFX 12 was chosen as the numerical tool. This investigation will be supported by using the finite time thermodynamic theory. At the beginning preliminary numerical tests were performed in order to validate the numerical methods and the boundary conditions implemented in CFX. The numerical calculations of the Rijke tube were carried out and the results were...
The numerical method for modeling of the transonic steam flows with homogeneous and/or heterogene... more The numerical method for modeling of the transonic steam flows with homogeneous and/or heterogeneous condensation has been presented. The experiments carried out for the Laval nozzles, for 2-D turbine cascades and for a 3-D flow in real turbine were selected to validate an in-house CFD code adjusted to the calculations of the steam condensing flows in complicated geometries. The sensitivity of the condensation model and difficulties in the validation process of the CFD code have been discussed. These difficulties limit the possibilities of verification and improvement of the condensation theory based on the existing experimental data.
The paper presents a description of two models dedicated to steam condensing flow modeling. The m... more The paper presents a description of two models dedicated to steam condensing flow modeling. The models are implemented into an in-house computational fluid dynamics (CFD) code that has been successfully applied to a wet steam flow calculation for many years now. Both models use the same condensation model that has been validated against the majority of available experimental data. The state equations for vapor and liquid water, the physical model as well as the numerical techniques of solution to flow governing equations have been presented. For the single-fluid model (SFM), the Reynolds-averaged Navier-Stokes (RANS) equations for vapor/liquid mixture are solved, whereas the two-fluid model solves separate flow governing equations for the compressible, viscous and turbulent vapor phase and for the compressible and inviscid liquid phase.
The aim of this paper is to assess the impact of the mutual positioning of the turbine stage stat... more The aim of this paper is to assess the impact of the mutual positioning of the turbine stage stator and rotor blades on noise generation. The Ansys CFX commercial software package and the Scale-Adaptive Simulation (SAS) hybrid turbulence model are used for numerical analyses. The paper is focused on an analysis that the pressure wave generation resulting from unsteady flow phenomena. In order to present the problem, the Fast Fourier Transformation (FFT) analysis of pressure fluctuation is carried out at selected points of the turbine stage computational domain. A comparison of values of individual components for subsequent control points allows an approximate determination of the place of generation of pressure waves, the direction of their propagation and the damping rate. Moreover, the numerical analyses make it possible to evaluate the justification for the use of the SAS model, which is rather demanding in terms of equipment, in simulations of unsteady flow fields where generation and propagation of noise waves occur.
The solution of the AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS... more The solution of the AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS) or even the Large Eddy Simulation (LES) for a large computational domain is very time consuming and cannot be applied widely for engineering applications. In this paper the in-house CFD and CAA codes are presented. The in-house CFD code is based on the LES approach whereas the CAA code is an acoustic postprocessor solving the non-linearized Euler equations for fluctuating (acoustic) variables. These codes are used to solve the aerodynamically generated sound field by a flow over a rectangular cavity with inlet Mach number 0.53. Figure 5. The computational domain of the cavity and boundary conditions for EAP-CAA modeling.
This paper presents an analysis of the operation of a stage of an aircraft engine gas turbine in ... more This paper presents an analysis of the operation of a stage of an aircraft engine gas turbine in terms of generation of flow losses. The energy loss coefficient, the entropy loss coefficient and an additional pressure loss coefficient were adopted to describe the losses quantitatively. Distributions of loss coefficients were presented along the height of the blade channel. All coefficients were determined based on the data from the unsteady flow field and analyzed for different mutual positioning of the stator and rotor blades. The flow calculations were performed using the Ansys CFX commercial software package. The analyses presented in this paper were carried out using the URANS (Unsteady Reynolds-Averaged Navier-Stokes) method and two different turbulence models: the common Shear Stress Transport (SST) model and the Adaptive-Scale Simulation (SAS) turbulence model, which belongs to the group of hybrid models.
ABSTRACT The aim of this work is to estimate the losses in the steam flow through the LP steam tu... more ABSTRACT The aim of this work is to estimate the losses in the steam flow through the LP steam turbine rotor and the whole stage. For steam flow two types of losses take place, aerodynamic (profile, secondary flow, leakage) and thermodynamic (due to the heat addition caused by condensation). Presented numerical results are split into two groups. In the first part of this work the comparison of the three different calculation methods of steam flow is carried out. To this end the geometry of LP steam turbine last rotor is chosen. The first method is a Streamline Curvature Method (SCM) used on the meridional plane with losses correlations, and the next two methods, commercial and an in-house CFD codes, solve the Reynolds averaged Navier-Stokes equations for a 3-D flow. Below the saturation line the first two codes model equilibrium steam properties, and the last one models non-equilibrium steam properties. Then for the geometry of the penultimate stage, with the use of an in-house CFD code, the comparison of the different types of condensation models on the losses prediction is examined.
In turbomachinery, an influence of a tip-leakage flow on overall blade loss is crucial and its re... more In turbomachinery, an influence of a tip-leakage flow on overall blade loss is crucial and its reduction is still worth striving for. In this paper a numerical analysis of the flow in tip seal of high-rotating gas turbine engine has been made. This analysis is a part of experimental research for testing the commercially used different tip seals solutions. Described test rig is predicted to be an universal tool for developing and examining different configurations of turbine blade tips. Presented numerical analysis is used to predict physical phenomena that may affect the rotor blade performance. In the numerical investigation the commercial Ansys CFX software was employed. The most important parameters were: mass flow rate at the inlet and outlet of the test bench, pressure and velocity distribution and the air temperature growth above the rotor. Also, an influence of test rig inlet and outlet geometry on flow uniformity was investigated. During the analysis the attention was focused also on minimizing the turbulence intensity in outlet area, that could cause significant difficulties in flow and stable work of the machine-generated eddies contributes to lower the mass flow rate.
Atmospheric air is a commonly used working fluid in turbomachinery. The air typically contains a ... more Atmospheric air is a commonly used working fluid in turbomachinery. The air typically contains a certain amount of suspended solid particles, as well as water in the form of vapor or droplets. In the current paper, we focus on the numerical modeling of humid air transonic flow in turbomachinery. In this paper we demonstrate a rarely considered, but as presented herein important influence of air humidity, pollution and liquid water content on the performance of the first stage of the gas turbine compressor and turbofan engine fan (NASA rotors 37 and 67). We also discuss the impact of the interfacial heat transfer associated with steam condensation or water evaporation on the distribution of stagnation parameters at the rotor outlet, the rotor performance, and flow conditions, as well as losses. Results demonstrate the impact of the number of pollution particles and water droplets on the compression process in the analyzed rotors, especially on the Mach number distribution in the blad...
The supersonic nozzle is very often used in many technical applications, such as fluid-flow machi... more The supersonic nozzle is very often used in many technical applications, such as fluid-flow machines or devices. If the medium flowing through a supersonic nozzle is a moist gas, moist air or wet steam, non-equilibrium condensation must occur. Such mediums usually contain impurities which affect the condensation phenomenon. The main purpose of this research is a numerical study on the effect of the content of impurities in steam on the non-equilibrium condensation phenomenon. In order to achieve this purpose, salt (NaCl) is used. Sodium chloride (NaCl) is a very common steam impurity. It may occur in a soluble or crystal form. Different concentrations of salt are considered as the input quantity. The results show that the process of steam condensation on salt particles has a significant impact on two-phase variables and flow parameters. In the presence of salt, steam condensation starts whenever the supersaturation ratio is above one. Latent heat of the condensation changes the flow pattern and reduces the nucleation rate and water droplet production. The presence of 10 15 particles of salt reduces the outlet average liquid mass fraction and entropy generation by 14.5 % and 15.2 % respectively. The research results prove that steam impurities have a significant impact on non-equilibrium condensation.
This article deals with the turbulent transition phenomenon modelling and its influence on heat t... more This article deals with the turbulent transition phenomenon modelling and its influence on heat transfer. The purpose of the analyses was to verify the transition modelling implemented in the ANSYS CFX 11 commercial code for popular test cases (low flow speed) described in literature, and then use it for verification of the in-house CFD code (created for compressible flows). The in-house CFD code has been extended lately for the Conjugate Heat Transfer modelling (CHT) as well, taking into account important flow effects, especially the turbulent transition. A Wilcox k-ω turbulence model with the Low-Reynolds modification was used in the in-house code. The calculations in ANSYS CFX were made using an SST turbulence model and a γ-Θ transition model. A fully turbulent flow was modelled by means of both codes, and the results were compared with the available experimental data. Then, the turbulent transition for several test cases was analysed with ANSYS CFX. Afterwards, the in-house CFD ...
This article deals with the turbulent transition phenomenon modelling and its influence on heat t... more This article deals with the turbulent transition phenomenon modelling and its influence on heat transfer. The purpose of the analyses was to verify the transition modelling implemented in the ANSYS CFX 11 commercial code for popular test cases (low flow speed) described in literature, and then use it for verification of the in-house CFD code (created for compressible flows). The in-house CFD code has been extended lately for the Conjugate Heat Transfer modelling (CHT) as well, taking into account important flow effects, especially the turbulent transition. A Wilcox k-ω turbulence model with the Low-Reynolds modification was used in the in-house code. The calculations in ANSYS CFX were made using an SST turbulence model and a γ-Θ transition model. A fully turbulent flow was modelled by means of both codes, and the results were compared with the available experimental data. Then, the turbulent transition for several test cases was analysed with ANSYS CFX. Afterwards, the in-house CFD ...
In the Institute of Power Engineering and Turbomachinery of The Silesian University of Technology... more In the Institute of Power Engineering and Turbomachinery of The Silesian University of Technology the experimental research have been performed from many years now. To this end a mini steam power station located in Machinery Hall is used. It is unique non-commercial installation of such kind in Europe, consisting of a steam boiler, steam turbine with condenser, electric generator, cooling tower and tunnel to test the wet steam flows. In this paper has been presented purpose and construction of wet steam tunnel and plans for its use. In the present state of this tunnel is an interesting research installation for the analysis of many problems of flow.
In steam condensing turbines of a large output the low-pressure stages operating in wet steam reg... more In steam condensing turbines of a large output the low-pressure stages operating in wet steam regime produce over 10% total output capacity. Their efficiency is significantly lower than the efficiency of the stages working in superheated steam regime. In the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology there is an experimental facility dedicated to the wet steam flow investigation through the nozzles and linear cascades, especially to the identification of the both aerodynamic and thermodynamic losses. This work includes a description of the losses definitions using in an analysis of the flow efficiency of the low-pressure steam stages. There will be presented a method for losses analysis in the wet steam transonic flow by means of an existing in the Institute steam facility.
The present paper describes an experimental and numerical study of steam condensing flow in a lin... more The present paper describes an experimental and numerical study of steam condensing flow in a linear cascade of turbine stator blades. The experimental research was performed on the facility of a small scale steam power plant located at Silesian University of Technology in Gliwice. The test rig of the facility allows us to perform the tests of steam transonic flows for the conditions corresponding to these which prevail in the low-pressure (LP) condensing steam turbine stages. The experimental data of steam condensing flow through the blade-to-blade stator channel were compared with numerical results obtained using the in-house CFD numerical code TraCoFlow. Obtained results confirmed a good quality of the performed experiment and numerical calculations.
The power technologies with steam turbines generate more than 60% of the electricity for the enti... more The power technologies with steam turbines generate more than 60% of the electricity for the entire world and the world electricity generation is projected to become about 1.5 times as large as the current demand in 2013 until 2035. Consequently, the development and practical implementation of the efficiency enhancement technology of steam turbines for power generation should be driven to supply the necessary electricity while restraining and reducing global greenhouse gas emissions. The wet steam constitutes a serious problem in condensing steam turbines, contributing to the additional losses generation and erosion processes. In order to reduce this type of losses the better understanding of the phenomena undergoing in wet steam transonic flows is necessary. In spite of many numerical and experimental research in this field many issues are still not recognized and not clearly explained. The presented work concerns a novel experimental research comprising the new and more effective ...
Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flow w... more Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flow were carried out in linear blade cascade. The linear cascade consists of the stator blades of the low pressure steam turbine last stage. The applied experimental test section is a part of a small scale steam power plant located at Silesian University of Technology. The steam parameters at the test section inlet correspond to the real conditions in low pressure part of 200MWe steam turbine. The static pressure measurements on the blade surface as well as the Schlieren pictures were used to assess the flow field in linear cascade of the steam turbine stator blades. The capabilities of used measurement techniques were estimated for gaining knowledge of condensation process in linear blade cascade.
The goal of the presented work is an optimization of the geometrical configuration of the tip sea... more The goal of the presented work is an optimization of the geometrical configuration of the tip seal with a honeycomb land, to reduce the leakage flow in the counter-rotating LP turbine of a contra-rotating open rotor aero-engine. This goal was achieved with the use of the Ansys-CFX commercial code and an in-house optimization procedure. The detailed studies including the mesh influence, the stages of the computational domain simplification, and geometry variants are discussed. The optimization process is based on a single objective genetic algorithm (SOGA). The automatic grid generation process and the CFD calculations are based on scripts prepared under the Ansys-ICEM and Ansys-CFX software. The whole procedure is written in the Visual Basic for Applications language (VBA), which allows a direct access to the CAD software with the use of macros and allows a proper connection between the CAD environment and the CFD software. The described algorithm allows parallel computing. In addit...
Przemysł energetyczny na całym świecie wyznaczył sobie ambitny cel: przesunięcie granicy sprawnoś... more Przemysł energetyczny na całym świecie wyznaczył sobie ambitny cel: przesunięcie granicy sprawności netto bloków węglowych z obecnej wartości referencyjnej 46% do 50% i wyższej. Przekroczenie symbolicznej bariery 50% wymaga znaczących zmian technologicznych, a w szczególności ogromnego postępu w dziedzinie inżynierii materiałowej. Ogromne koszty związane z zastosowaniem stopów niklowych w podstawowych elementach bloku parowego zmusiły do dużego kroku w obszarze górnych parametrów termodynamicznych obiegu parowego i rozpoczęcia w technologii elektrowni parowych następnej fazy rozwojowej – zaawansowanych parametrów ultra-nadkrytycznych (A-USC – advanced ultra-supercritical). Za cel rozwoju energetyki zawodowej w Europie przyjęto osiągnięcie temperatury pary wynoszącej 700°C i ciśnienia 35 MPa, co być może pozwoli na osiągnięcie sprawności bloku netto 50%. Osiągnięcie tak wysokich parametrów pary w blokach węglowych wymaga zastosowania nowych materiałów konstrukcyjnych do budowy kotła ...
The presented paper shows our first step into the numerical modelling of the thermoacoustic pheno... more The presented paper shows our first step into the numerical modelling of the thermoacoustic phenomenon. The thermoacoustic effect has a great application potential, for instance, in thermoacoustic engines or thermoacoustic mixture separation. These two applications are in the centre of our interest. The modelling of thermoacoustic effects consists in a solution of transport equations, mass, momentum and energy, to identify the influence of heat transfer on the sonic oscillation and vice versa. The numerical modelling of such sensitive and sophisticated phenomena requires a high quality numerical tool. The commercial CFD code ANSYS CFX 12 was chosen as the numerical tool. This investigation will be supported by using the finite time thermodynamic theory. At the beginning preliminary numerical tests were performed in order to validate the numerical methods and the boundary conditions implemented in CFX. The numerical calculations of the Rijke tube were carried out and the results were...
The numerical method for modeling of the transonic steam flows with homogeneous and/or heterogene... more The numerical method for modeling of the transonic steam flows with homogeneous and/or heterogeneous condensation has been presented. The experiments carried out for the Laval nozzles, for 2-D turbine cascades and for a 3-D flow in real turbine were selected to validate an in-house CFD code adjusted to the calculations of the steam condensing flows in complicated geometries. The sensitivity of the condensation model and difficulties in the validation process of the CFD code have been discussed. These difficulties limit the possibilities of verification and improvement of the condensation theory based on the existing experimental data.
The paper presents a description of two models dedicated to steam condensing flow modeling. The m... more The paper presents a description of two models dedicated to steam condensing flow modeling. The models are implemented into an in-house computational fluid dynamics (CFD) code that has been successfully applied to a wet steam flow calculation for many years now. Both models use the same condensation model that has been validated against the majority of available experimental data. The state equations for vapor and liquid water, the physical model as well as the numerical techniques of solution to flow governing equations have been presented. For the single-fluid model (SFM), the Reynolds-averaged Navier-Stokes (RANS) equations for vapor/liquid mixture are solved, whereas the two-fluid model solves separate flow governing equations for the compressible, viscous and turbulent vapor phase and for the compressible and inviscid liquid phase.
The aim of this paper is to assess the impact of the mutual positioning of the turbine stage stat... more The aim of this paper is to assess the impact of the mutual positioning of the turbine stage stator and rotor blades on noise generation. The Ansys CFX commercial software package and the Scale-Adaptive Simulation (SAS) hybrid turbulence model are used for numerical analyses. The paper is focused on an analysis that the pressure wave generation resulting from unsteady flow phenomena. In order to present the problem, the Fast Fourier Transformation (FFT) analysis of pressure fluctuation is carried out at selected points of the turbine stage computational domain. A comparison of values of individual components for subsequent control points allows an approximate determination of the place of generation of pressure waves, the direction of their propagation and the damping rate. Moreover, the numerical analyses make it possible to evaluate the justification for the use of the SAS model, which is rather demanding in terms of equipment, in simulations of unsteady flow fields where generation and propagation of noise waves occur.
The solution of the AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS... more The solution of the AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS) or even the Large Eddy Simulation (LES) for a large computational domain is very time consuming and cannot be applied widely for engineering applications. In this paper the in-house CFD and CAA codes are presented. The in-house CFD code is based on the LES approach whereas the CAA code is an acoustic postprocessor solving the non-linearized Euler equations for fluctuating (acoustic) variables. These codes are used to solve the aerodynamically generated sound field by a flow over a rectangular cavity with inlet Mach number 0.53. Figure 5. The computational domain of the cavity and boundary conditions for EAP-CAA modeling.
This paper presents an analysis of the operation of a stage of an aircraft engine gas turbine in ... more This paper presents an analysis of the operation of a stage of an aircraft engine gas turbine in terms of generation of flow losses. The energy loss coefficient, the entropy loss coefficient and an additional pressure loss coefficient were adopted to describe the losses quantitatively. Distributions of loss coefficients were presented along the height of the blade channel. All coefficients were determined based on the data from the unsteady flow field and analyzed for different mutual positioning of the stator and rotor blades. The flow calculations were performed using the Ansys CFX commercial software package. The analyses presented in this paper were carried out using the URANS (Unsteady Reynolds-Averaged Navier-Stokes) method and two different turbulence models: the common Shear Stress Transport (SST) model and the Adaptive-Scale Simulation (SAS) turbulence model, which belongs to the group of hybrid models.
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Papers by Sławomir Dykas