Anton Bergant - Academia.edu (original) (raw)

Papers by Anton Bergant

IOP conference series, Mar 27, 2019

Water Power, 1988

Computer simulation of butterfly inlet valves (throughflow, lattice) in hydropower schemes is pre... more Computer simulation of butterfly inlet valves (throughflow, lattice) in hydropower schemes is presented. The software is intended for practisting engineers to obtain significant parameters for final design of valves and its auxiliary equipment. The concept of systematical modelling of program units is applied in computer processing. The processing is divided into two parts: hydrodynamic analysis and basic mechanical design of the butterfly valve. An application of the program package for analysis of throughflow valve in hydropower plant with Francis turbine is also presented. Results of analysis are shown graphically and discussed from designer's point of view.

Forschung Im Ingenieurwesen-engineering Research, Nov 4, 2011

A new vertical single-regulated mixed-flow turbine with conical guide apparatus and without spira... more A new vertical single-regulated mixed-flow turbine with conical guide apparatus and without spiral casing is presented in this paper. Runner blades are fixed to the hub and runner band and resemble to the Francis type runner of extremely high specific speed. Due to lack of information and guidelines for the design of a new turbine, a theoretical model was developed in order to determinate the design duty point, i.e. to determine the optimum narrow operation range of the turbine. It is not necessary to know the kinematic conditions at the runner inlet, but only general information on the geometry of turbine flow-passage, meridional contour of the runner and blading, the number of blades and the turbine speed of rotation. The model is based on the integral tangential lift coefficient, which is the average value over the entire runner blading. The results are calculated for the lift coefficient 0.5 and 0.6, for the flow coefficient range from 0.2 to 0.36, for the number of the blades between 5 and 13, and are finally presented in the Cordier diagram (specific speed vs. specific diameter). Calculated results of the turbine optimum operation in Cordier diagram correspond very well to the adequate area of Kaplan turbines with medium and low specific speed and extends into the area of Francis turbines with high specific speed. Presented model clearly highlights the parameters that affect specific load of the runner blade row and therefore the optimum turbine operation (discharge—turbine head). The presented method is not limited to a specific reaction type of the hydraulic turbine. The method can therefore be applied to a wide range from mixed-flow (radial-axial) turbines to the axial turbines. Applicability of the method may be considered as a tool in the first stage of the turbine design i.e. when designing the meridional geometry and selecting the number of blades according to calculated operating point. Geometric and energy parameters are generally defined to an extent that these parameters are considered in detailed design using turbulent viscous flow CFD solver.ZusammenfassungDargestellt wird eine neue vertikale einfach regulierte diagonale Rohrturbine mit konischem Leitapparat und ohne Spiralgehäuse. Die Laufradschaufeln sind an der Laufradnabe und dem Laufradkranz befestigt. Der Drehzahl nach gleicht das Laufrad dem Francislaufrad; es weist eine extrem hohe spezifische Drehzahl auf. Infolge der nicht verfügbaren Angaben und Anweisungen für die Gestaltung der neuen Turbine wird ein theoretisches Modell der Bestimmung des Betriebspunktes, bzw. der Bestimmung des engeren Bereichs des optimalen Betriebs der ganzen Turbine entwickelt. Für die Berechnung ist es nicht notwendig, kinematische Konstellationen bei dem Laufradeintritt zu kennen, sondern nur die Grundangaben: die Geometrie des Strömungskanals der Turbine, die Meridiankontur von Laufrad und Schaufeln, die Zahl dieser Schaufeln und die Turbinen-Drehgeschwindigkeit. Das Modell basiert auf dem Integralkoeffizienten des tangentialen Auftriebs, das einen Durchschnittswert über die ganze Beschaufelung des Laufrads darstellt. Die Berechnungen erfolgen für die Werte der Auftriebskoeffizienten von 0,5 und 0,6; für die Durchflusszahlen von 0,2 bis 0,36 und für die Schaufelzahl von 5 bis 13. Die Berechnungsergebnisse sind im Cordierdiagramm (spezifische Drehzahl – spezifischer Durchmesser) dargestellt. Der berechnete Bereich des optimalen Betriebs deckt sich weitgehend mit dem Bereich der Kaplanturbinen mit einer mittleren oder niedrigen spezifischen Drehzahl, und dehnt sich in den Bereich der Francisturbinen mit einer hohen spezifischen Drehzahl aus. Das entwickelte Modell hebt klar die Parameter hervor, die Einfluss auf die spezifische Belastung der Beschaufelung des Laufrads und dadurch auf den engeren optimalen Betriebsbereich der Turbine (Durchfluss–Fallhöhe) ausüben. Die Methode beschränkt sich nicht nur auf einen bestimmten Typ von Reaktionsturbinen, sondern lässt sich im ganzen Bereich von Radialaxialturbinen bis reinen Axialturbinen anwenden. Die Anwendbarkeit der Methode kann als Werkzeug in den ersten Phasen der Turbinenentwurf betrachtet werden; nämlich in der Gestaltung der Meridiangeometrie und bei der Wahl der Laufradschaufelzahl aufgrund des berechneten Betriebspunktes. Die geometrischen und energetischen Parameter sind hauptsächlich in dem Maße definiert, dass sie bei der weiteren Ausführungsplanung der Beschaufelung unter Anwendung der CFD Solvers für die turbulente Strömung berücksichtigt werden können.

Journal of Hydraulic Research, 1994

Journal of physics, Nov 1, 2022

Engineering Failure Analysis, Oct 1, 2021

Abstract This paper investigates unsteady flow phenomena in a new oil-hydraulic small-diameter pi... more Abstract This paper investigates unsteady flow phenomena in a new oil-hydraulic small-diameter pipeline apparatus at the Wroclaw University of Science and Technology, Poland. The steel pipe section lengths can be either 2 or 7 m, and the internal pipe diameter 4 mm (micro-hydraulic system). Transient event was triggered by a rapid closure of a downstream end bi-directional poppet valve. Pressures and velocities were investigated at the pipe end points. The main objective was to investigate effects of valve action on pressure magnitudes and timing in a number of transient laminar flow situations. In the method of characteristics numerical simulations a quasi-steady and a novel computationally effective Urbanowicz’s convolution-based unsteady friction models were used, as well as a quadratic bi-directional poppet valve function boundary condition. Comparisons between measured and calculated results clearly show that the valve closure path and the unsteady friction control the effects of unsteadiness on attenuation, shape and timing of pressure pulses in a small-diameter pipeline system; however, the unsteady friction is less important for the cases characterized by a relatively large fluid hammer number.

Structural integrity, 2022

Water

Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the wate... more Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the water hammer phenomenon is unacceptable. This resistance plays a major role when the transient liquid flow occurs in rigid-walled pipes (steel, copper, etc.). In the literature, there are at least two different modelling approaches to skin friction. The first group consists of models based on instantaneous changes in local and convective velocity derivatives, and the second group are models based on the convolution integral and full history of the flow. To date, more popular models are those from the first group, but their use requires empirical coefficients. The second group is still undervalued, even if based on good theoretical foundations and does not require any empirical coefficients. This is undoubtedly related to the calculation complexity of the convolution integral. In this work, a new improved effective solution of this integral is further validated, which is characterised with th...

Journal of Hydraulic Research, May 1, 2008

The AM is defined by the National Information Standards Organization as: "The version of a journa... more The AM is defined by the National Information Standards Organization as: "The version of a journal article that has been accepted for publication in a journal." This means the version that has been through peer review and been accepted by a journal editor. When you receive the acceptance email from the Editorial Office we recommend that you retain this article for future posting. Embargoes apply (see PDF | Excel for applicable embargo periods) if you are posting the AM to an institutional or subject repository, or to academic social networks like Mendeley, ResearchGate, or Academia.edu. Embargo for Journal of Hydraulic Research is 12 months.

Journal of Sound and Vibration

IOP Conference Series: Earth and Environmental Science

Refurbishment and upgrading of ageing hydropower plants contribute to increase of renewable energ... more Refurbishment and upgrading of ageing hydropower plants contribute to increase of renewable energy share in modern electrical grid systems. The potential increase of discharge and flexibility of load variation may result in much higher dynamic loads on both refurbished and non-refurbished plant components during transient operating events. First, water hammer control strategies are outlined including operational scenarios, surge control devices, redesign of the pipeline components, or limitation of operating conditions. Water hammer models and solutions are briefly discussed in the light of their capability, availability and uncertainty. The core of the paper is devoted to investigations of water hammer effects in a high-head hydropower plant Piva, Montenegro which is currently in the final phase of refurbishment. The flow-passage system of the Piva HPP is comprised of the intake structure, followed by three parallel penstocks each with Francis type water turbine at the downstream e...

11th International Conference on Pressure Surges, 2012

IOP conference series, Mar 27, 2019

Water Power, 1988

Computer simulation of butterfly inlet valves (throughflow, lattice) in hydropower schemes is pre... more Computer simulation of butterfly inlet valves (throughflow, lattice) in hydropower schemes is presented. The software is intended for practisting engineers to obtain significant parameters for final design of valves and its auxiliary equipment. The concept of systematical modelling of program units is applied in computer processing. The processing is divided into two parts: hydrodynamic analysis and basic mechanical design of the butterfly valve. An application of the program package for analysis of throughflow valve in hydropower plant with Francis turbine is also presented. Results of analysis are shown graphically and discussed from designer's point of view.

Forschung Im Ingenieurwesen-engineering Research, Nov 4, 2011

A new vertical single-regulated mixed-flow turbine with conical guide apparatus and without spira... more A new vertical single-regulated mixed-flow turbine with conical guide apparatus and without spiral casing is presented in this paper. Runner blades are fixed to the hub and runner band and resemble to the Francis type runner of extremely high specific speed. Due to lack of information and guidelines for the design of a new turbine, a theoretical model was developed in order to determinate the design duty point, i.e. to determine the optimum narrow operation range of the turbine. It is not necessary to know the kinematic conditions at the runner inlet, but only general information on the geometry of turbine flow-passage, meridional contour of the runner and blading, the number of blades and the turbine speed of rotation. The model is based on the integral tangential lift coefficient, which is the average value over the entire runner blading. The results are calculated for the lift coefficient 0.5 and 0.6, for the flow coefficient range from 0.2 to 0.36, for the number of the blades between 5 and 13, and are finally presented in the Cordier diagram (specific speed vs. specific diameter). Calculated results of the turbine optimum operation in Cordier diagram correspond very well to the adequate area of Kaplan turbines with medium and low specific speed and extends into the area of Francis turbines with high specific speed. Presented model clearly highlights the parameters that affect specific load of the runner blade row and therefore the optimum turbine operation (discharge—turbine head). The presented method is not limited to a specific reaction type of the hydraulic turbine. The method can therefore be applied to a wide range from mixed-flow (radial-axial) turbines to the axial turbines. Applicability of the method may be considered as a tool in the first stage of the turbine design i.e. when designing the meridional geometry and selecting the number of blades according to calculated operating point. Geometric and energy parameters are generally defined to an extent that these parameters are considered in detailed design using turbulent viscous flow CFD solver.ZusammenfassungDargestellt wird eine neue vertikale einfach regulierte diagonale Rohrturbine mit konischem Leitapparat und ohne Spiralgehäuse. Die Laufradschaufeln sind an der Laufradnabe und dem Laufradkranz befestigt. Der Drehzahl nach gleicht das Laufrad dem Francislaufrad; es weist eine extrem hohe spezifische Drehzahl auf. Infolge der nicht verfügbaren Angaben und Anweisungen für die Gestaltung der neuen Turbine wird ein theoretisches Modell der Bestimmung des Betriebspunktes, bzw. der Bestimmung des engeren Bereichs des optimalen Betriebs der ganzen Turbine entwickelt. Für die Berechnung ist es nicht notwendig, kinematische Konstellationen bei dem Laufradeintritt zu kennen, sondern nur die Grundangaben: die Geometrie des Strömungskanals der Turbine, die Meridiankontur von Laufrad und Schaufeln, die Zahl dieser Schaufeln und die Turbinen-Drehgeschwindigkeit. Das Modell basiert auf dem Integralkoeffizienten des tangentialen Auftriebs, das einen Durchschnittswert über die ganze Beschaufelung des Laufrads darstellt. Die Berechnungen erfolgen für die Werte der Auftriebskoeffizienten von 0,5 und 0,6; für die Durchflusszahlen von 0,2 bis 0,36 und für die Schaufelzahl von 5 bis 13. Die Berechnungsergebnisse sind im Cordierdiagramm (spezifische Drehzahl – spezifischer Durchmesser) dargestellt. Der berechnete Bereich des optimalen Betriebs deckt sich weitgehend mit dem Bereich der Kaplanturbinen mit einer mittleren oder niedrigen spezifischen Drehzahl, und dehnt sich in den Bereich der Francisturbinen mit einer hohen spezifischen Drehzahl aus. Das entwickelte Modell hebt klar die Parameter hervor, die Einfluss auf die spezifische Belastung der Beschaufelung des Laufrads und dadurch auf den engeren optimalen Betriebsbereich der Turbine (Durchfluss–Fallhöhe) ausüben. Die Methode beschränkt sich nicht nur auf einen bestimmten Typ von Reaktionsturbinen, sondern lässt sich im ganzen Bereich von Radialaxialturbinen bis reinen Axialturbinen anwenden. Die Anwendbarkeit der Methode kann als Werkzeug in den ersten Phasen der Turbinenentwurf betrachtet werden; nämlich in der Gestaltung der Meridiangeometrie und bei der Wahl der Laufradschaufelzahl aufgrund des berechneten Betriebspunktes. Die geometrischen und energetischen Parameter sind hauptsächlich in dem Maße definiert, dass sie bei der weiteren Ausführungsplanung der Beschaufelung unter Anwendung der CFD Solvers für die turbulente Strömung berücksichtigt werden können.

Journal of Hydraulic Research, 1994

Journal of physics, Nov 1, 2022

Engineering Failure Analysis, Oct 1, 2021

Abstract This paper investigates unsteady flow phenomena in a new oil-hydraulic small-diameter pi... more Abstract This paper investigates unsteady flow phenomena in a new oil-hydraulic small-diameter pipeline apparatus at the Wroclaw University of Science and Technology, Poland. The steel pipe section lengths can be either 2 or 7 m, and the internal pipe diameter 4 mm (micro-hydraulic system). Transient event was triggered by a rapid closure of a downstream end bi-directional poppet valve. Pressures and velocities were investigated at the pipe end points. The main objective was to investigate effects of valve action on pressure magnitudes and timing in a number of transient laminar flow situations. In the method of characteristics numerical simulations a quasi-steady and a novel computationally effective Urbanowicz’s convolution-based unsteady friction models were used, as well as a quadratic bi-directional poppet valve function boundary condition. Comparisons between measured and calculated results clearly show that the valve closure path and the unsteady friction control the effects of unsteadiness on attenuation, shape and timing of pressure pulses in a small-diameter pipeline system; however, the unsteady friction is less important for the cases characterized by a relatively large fluid hammer number.

Structural integrity, 2022

Water

Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the wate... more Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the water hammer phenomenon is unacceptable. This resistance plays a major role when the transient liquid flow occurs in rigid-walled pipes (steel, copper, etc.). In the literature, there are at least two different modelling approaches to skin friction. The first group consists of models based on instantaneous changes in local and convective velocity derivatives, and the second group are models based on the convolution integral and full history of the flow. To date, more popular models are those from the first group, but their use requires empirical coefficients. The second group is still undervalued, even if based on good theoretical foundations and does not require any empirical coefficients. This is undoubtedly related to the calculation complexity of the convolution integral. In this work, a new improved effective solution of this integral is further validated, which is characterised with th...

Journal of Hydraulic Research, May 1, 2008

The AM is defined by the National Information Standards Organization as: "The version of a journa... more The AM is defined by the National Information Standards Organization as: "The version of a journal article that has been accepted for publication in a journal." This means the version that has been through peer review and been accepted by a journal editor. When you receive the acceptance email from the Editorial Office we recommend that you retain this article for future posting. Embargoes apply (see PDF | Excel for applicable embargo periods) if you are posting the AM to an institutional or subject repository, or to academic social networks like Mendeley, ResearchGate, or Academia.edu. Embargo for Journal of Hydraulic Research is 12 months.

Journal of Sound and Vibration

IOP Conference Series: Earth and Environmental Science

Refurbishment and upgrading of ageing hydropower plants contribute to increase of renewable energ... more Refurbishment and upgrading of ageing hydropower plants contribute to increase of renewable energy share in modern electrical grid systems. The potential increase of discharge and flexibility of load variation may result in much higher dynamic loads on both refurbished and non-refurbished plant components during transient operating events. First, water hammer control strategies are outlined including operational scenarios, surge control devices, redesign of the pipeline components, or limitation of operating conditions. Water hammer models and solutions are briefly discussed in the light of their capability, availability and uncertainty. The core of the paper is devoted to investigations of water hammer effects in a high-head hydropower plant Piva, Montenegro which is currently in the final phase of refurbishment. The flow-passage system of the Piva HPP is comprised of the intake structure, followed by three parallel penstocks each with Francis type water turbine at the downstream e...

11th International Conference on Pressure Surges, 2012