Sławomir Dykas

Silesian University of Technology · Institute of Power Engineering and Turbomachinery

Coughing and sneezing are the main ways of spreading coronavirus-2019 (SARS-CoV-2). People sometimes need to work together at close distances. This study presents the results of the computational fluid dynamics (CFD) simulation of the dispersion and transport of respiratory drop-lets emitted by an infected person who coughs in an indoor space with...

Water droplet formation and growth in the nucleation process are crucial aspects of steam condensation in moist air flow, and they are accompanied by intensive heat exchange between phases. This study proposes a mathematical model for predicting heat transfer coefficients in the condensation process, which is applicable for single-phase and multiph...

Steam turbine is one of the most important components in fossil-fired and nuclear power plants, its efficiency is of great importance for saving energy and decreasing consumption. The steam density rapidly decreases when the steam expanses, and NaCl dissolved in steam starts precipitating. However, the presence of NaCl will not only affect the non-...

Inevitable and undesirable as it is, phase transition has a significant impact on the fluid flow efficiency in many energy processes. This paper deals with the impact of water vapour condensation and liquid water evaporation in the moist air expansion in a nozzle with a low expansion rate. The presented comprehensive analysis includes a numerical s...

The major goal of this study is comparing the results of heterogeneous and homogeneous condensation through a CD nozzle. The experimental technique for liquid phase assessment in wet steam transonic flow is tested under real conditions in an in-house steam tunnel test rig. The flow was modelled numerically using an in-house CFD code for performing...

Despite the wide possibilities of using a cycloidal rotor in the form of propulsion systems for unmanned aerial vehicles (UAV), cycloidal propellers for sea-going ships, rotors of wind turbines or sea or river cycloidal energy converters, there is practically no research on the use of this solution in the form of a cycloidal rotor fan (CRF) for HVA...

Condensation has a negative impact on turbomachinery efficiency in many energy processes. This paper compares the expansion of moist air in symmetric and asymmetric nozzles with a low expansion rate. The presented numerical study is supported by analytical and experimental research. The experimental tWesting was carried out using an in-house experi...

From the historical point of view, the research on cyclorotors has been focused on aviation applications, such as propulsion systems for UAVs. There is a need for studies on the use of a cycloidal rotor fan (CRF) in internal-flow applications, such as power or HVAC applications. This paper presents considerations of the cycloidal rotor application...

Cathode systems of proton exchange membrane fuel cells are tasked with providing compressed air for the fuel cell stack. The exhaust gas from the fuel cell has a pressure potential which can be utilised in a turbine to partially power the compressor. Therefore, a radial compressor and a radial turbine are often combined with an electric motor to fo...

We carried out many experiments in Laval nozzles and found out that among all the experimental data, some of them matched our numerical results and the rest did not. Therefore, we guessed maybe at the inlet the steam is not perfectly pure and there is wetness at the inlet. The wetness at the inlet is because of some instruments like desuperheater i...

In this paper numerical analysis of the condensing steam flow in a converging-diverging nozzle is investigated. The ANSYS Fluent results are compared with the results of the in-house academic Computational fluid dynamics code with respect to the capacity for thermodynamic assessment. The “local” real gas equation of state is used as a mathematical...

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...

Steam turbines play a critical role in power generation systems. Therefore, increasing the efficiency of steam turbines is highly desirable, especially in LP stages. One of the suggested techniques to reduce wetness losses in LP stages is the hot steam injection. In the first section of the present study, the effect of 3D turbine blade span length...

Thermodynamic losses and blade erosion occur due to formation of wetness in the low-pressure steam turbine. By changing the trailing edge angle of turbine blade can reduce blade erosion and condensation losses. This research optimized the best of the trailing edge rotation to improve the turbine's operation at the low-pressure part of the steam tur...

The aim of this paper is to thoroughly analyse the influence of condensation models on the modelling of condensation phenomena in transonic flows of moist air. The reason for the study was the fact that different condensation models are used by researchers to obtain satisfactory results of numerical modelling. The condensation models tested herein...

Low-grade thermal energy can be used for superheating the working fluid in the steam ejector. The purpose of the present study is to investigate the relationship of two-phase heat transfer with the ejector performance in the condensing flow regime under the condition of primary steam superheating. The condensation and evaporation phenomena occur in...

A fan with cycloidal rotor (CRF) becomes a popular idea in wide application such as aviation, HVAC (heat, ventilation and air conditioning) or marine propeller systems. This is due to advantages such as direct control of the flow direction, larger flow rates than in a conventional machines without cycloidal control. In the presented article, veloci...

The aim of this article is to thoroughly analyse the influence of condensation models on the modelling of condensation phenomena in transonic flow of moist air. The reason for the study was the fact that different condensation models are used by researchers to obtain satisfactory results of numerical modelling. The condensation models tested herein...

For many years, the Department of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a small-capacity (about 500 kWe) steam-gas power plant. Based on many years of experience in operation of this power plant utilizing the Velox-type gas-steam system, an idea arose to modify this type of thermal power cycle...

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...

The paper presents the results of thermodynamic and economic analysis of a compressed carbon dioxide energy storage system using low-pressure reservoir, where carbon dioxide cannot be stored at a high-pressure, like in standard concepts. Such limitations may occur in post-mining underground excavations, the availability of which will increase in th...

Flow separation commonly affects the stability of turbomachines, especially under low-flowrate conditions. Compared with conventional blades, a forward-swept blade is more efficient at high flowrates. However, experiments and numerical simulations show that a forward-swept blade produces an unstable region under low flowrate. In this paper, the top...

High-pressure abrasive water jet flushing (HPAWJF) is an effective method used to improve coal seam permeability. In this study, based on the theories of gas flow and coal deformation, a coupled gas-rock model is established to investigate realistic failure processes by introducing equations for the evolution of mesoscopic element damage along with...

One of the most popular working fluids in turbomachinery is atmospheric air. If the air has not been dried and cleaned before entering the turbomachine, it always contains a certain amount of water in form of water vapour or droplets and suspended solid particles. The paper presents a numerical model of the transonic condensing flow in a turbomachi...

The last few stages of a condensing steam turbine of fossil fuel power units and most stages of steam turbine in nuclear power units operate under wet steam conditions and the condensation phenomena as well as two-phase flow are crucial for efficiency of turbine stages. In this work, the water spray injection ahead of the vanes was used to control...

In recent years, the flow characteristics research of the interstage region in counter-rotating axial fans in terms of fluid dynamics has attracted much attention. Especially, the dynamic relationship between interstage pressure pulsation and blade vibration in counter-rotating axial fans has not yet been clarified. This paper performs the signal p...

The spontaneous condensation process takes place in many power engineering machines and devices, such as steam turbines, supersonic separators, ejectors etc. In the paper, the effect of the inlet steam superheat degree in steam condensing flow through the IWSEP (International Wet Steam Experimental Project) nozzle was investigated experimentally an...

The paper presents mathematical modelling of water vapour condensation process in the moist air tran-sonic internal flows. The condensation model based on the classical theory of nucleation and molecular-kinetic droplet growth model is implemented into a commercial software ANSYS Fluent. Two approaches are shown in the paper, one in which the air w...

The ejectors are widely employed in power engineering installations, both refrigeration, and thermal ones. In the paper, a steam ejector of a solar-driven refrigeration system is investigated numerically, using different CFD models , to reveal the flow structures and evaluate its performance. A modified nucleation model adopting the Benson and Shut...

The paper presents mathematical modelling of steam condensation in the atmospheric air transonic flows. A single-fluid model was employed. The model was validated against the in-house experimental studies of internal flow in nozzles and against benchmark tests available in literature i.e., RAE2822 transonic airfoil. The impact of air relative humid...

The paper presents studies of mathematical modelling in tran-sonic flow through the first stage rotor of the axial compressor of homogenous and heterogeneous condensation. The condensation phenomena implemented into a commercial software is based on the classical theory of nucleation and molecular-kinetic droplet growth model. Model is validated ag...

In this work, the cycloidal rotor fan (CRF) performance was estimated by means of a numerical method based on Unsteady Reynolds Averaged Navier-Stokes equations (URANS). The fan with a cycloidal rotor belongs to the positive displacement machines of the rotary type. The numerical algorithm for simulation of the flow in the cycloidal rotor as well a...

The paper presents CFD results for the transonic flow of dry and moist air through a diffuser and a compressor rotor. In both test geometries, i.e. the Sajben transonic diffuser and the NASA Rotor 37, the air humidity impact on the structure of flows with weak shock waves was examined. The CFD simulations were performed by means of an in-house CFD...

Secondary flows in turbomachinery highly affect the overall efficiency and rotor stability. A prime example of such a phenomenon are leakage flows. Despite their complexity, they can often be estimated with simple semi-empirical formulae, solved with hand calculations. Such an approach is much more cost and time effective during the design process....

The content of water vapour, liquid water or ice in a dispersed form in the atmospheric air is very common and it might affect the aerodynamic characteristics, especially in the transonic or supersonic flow regime. In the paper, special attention was paid to identifying the heat transfer phenomena appearing on a transition from sub- to supersonic,...

For many years, the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a small-capacity (about 500 kWe) steam-gas power plant. Based on many yearsof experience in operation of this power plant utilizing the Velox-type gas-steam system, an idea arose to modify this type of thermal power cycle to...

The experimental research, initiated at the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology at the end of the last century, created an opportunity to supplement knowledge about the phenomenon of steam flow with condensation, tested by numerical fluid mechanics by IMiUE employees. In parallel with the numer...

The paper presents a developed numerical tool in the form of a CFD code solving Reynolds-averaged Navier–Stokes equations for transonic flows of a compressible gas which is used to model the process of atmospheric air expansion in nozzles. The numerical model takes account of condensation of water vapour contained in atmospheric air. The paper pres...

In this paper, the investigation of the cycloidal rotor fan (CRF) was presented. A CRF with four blades of the NACA0012 profile was used for the analysis. The CFD calculations were carried out by means of Ansys CFX commercial software. The experimental tests were done using velocity field measurement with the LDA technique. Numerical results were c...

SYMKOM 2018 IMP2 13th International Symposium 18-20 October 2018 Łódź, Poland

This paper presents numerical and experimental testing of a cycloidal rotor fan (CRF). The tested cyclorotor is made of four NACA0012 profile blades. CFD calculations using the Ansys CFX® tool and the LDA measurement technique are performed to determine the fan performance for different operating parameters, i.e. rotational speed and the rotor blad...

This paper presents the results of research on the wet steam flow with spontaneous condensation in the de Laval nozzle. A comparison is made between the results of numerical modelling performed for two cases of boundary conditions obtained using an in-house CFD code and the Ansys CFX commercial package. The numerical modelling results are compared...

This paper presents the methodology and results of the optimization of a straight-through labyrinth seal with two inclined fins against smooth-land. The optimization was performed using commercial tools implemented in the ANSYS environment, such as goal-driven optimization. The response surfaces were created based on Latin hypercube samples found f...

W pracy przedstawiono metodykę badań eksperymentalnych i numerycznych prowadzonych w Instytucie Maszyn i Urządzeń Energetycznych Politechniki Śląskiej. Opisano instalację badawczą minisiłowni parowej oraz zintegrowany z nią tunel parowy służący do badań przepływu pary wodnej w wybranych płaskich (dwuwymiarowych) geometriach, takich jak dysze de Lav...

The primary goal of this study was to develop and experimentally validate the methodology of labyrinth seals optimization concerning leakage. The problem was investigated using the ANSYS CFX commercial software. This paper presents the methodology and results of the optimization of a straight-through labyrinth seal with two inclined fins against sm...

Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flows in a linear blade cascade were carried out. The cascade consists of the rotor blades of the low-pressure (LP) steam turbine last stage. The experimental testing facility is a part of a small-scale steam power plant located at the Silesian University of...

The purpose of the “International Wet Steam Modeling Project” is to review the ability of computational methods to predict condensing steam flows. The results of numerous wet-steam methods are compared with each other and with experimental data for several nozzle test cases. The spread of computed results is quite noticeable and the present paper e...

The paper presents the accurate assessment of the amount of gas flowing through three types of aero-engine expander sealing. Structures consisting of straight-through labyrinth seals-with one, two and three fins are considered. The study deploys two independent approaches. The first one focuses on the experimental research using high-precision test...

The paper presents an accurate assessment of the amount of gas flowing through three types of aero-engine expander sealing. Structures consisting of straight-through labyrinth seals-with one, two and three fins are considered. The study deploys two independent approaches. The first one focuses on the experimental research using high-precision test...

The subject of this paper is analysis of the cooling system of a conceptual advanced ultra-supercritical coal-fired power unit integrated with a CO2 capture and compression unit (CCU). The capture unit, based on wet chemical absorption using MEA (monoethanolamine), was modelled in Aspen PLUS. The obtained results were used in the power unit model d...

For many years, the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a Velox-type small-capacity gas-steam power unit for teaching and research purposes. The Velox-type gas-steam cycle is characterized by a much higher ratio of power obtained from the steam turbine and the gas turbine, respec...

This study presents experimental and numerical testing of the steam condensing flow through a linear blade cascade made of blades of a 200 MW steam turbine last stage stator. The tests were carried out on an in-house laboratory stand and using an in-house numerical code modelling the water vapour flow with homo- and heterogeneous condensation. Addi...

Atmospheric air always contains a certain amount of water vapour being an element of the Earth's hydrological cycle. This content, which can be defined by relative humidity for example, has a significant impact on the transonic flow field. What happens then is the water vapour rapid condensation, due to a non-equilibrium process of spontaneous cond...

This work aims to perform the detailed experimental investigation of the flow field in labyrinth seal specimen using optical methods: LDA (Laser Doppler Anemometry) and schlieren visualization. Preliminary tests were performed on a stationary (rotor model with labyrinth does not move), linear – where the curvature of the specimen is omitted – measu...

Powietrze atmosferyczne zawsze zawiera pewną ilość pary wodnej będącej elementem cyklu hydrologicznego Ziemi. Ilość pary wodnej zawartej w powietrzu, określana na przykład za pomocą wilgotności względnej, ma znaczący wpływ na okołodźwiękowe pole przepływu. Mamy wówczas do czynienia z gwałtownym procesem kondensacji pary wodnej, na skutek nierównowa...

This paper is an attempt at a systematic approach to the flow field analysis in the case of air flowing through a straight channel with a circular bump. The results of the authors' own experimental measurements are compared to those obtained by means of both an in-house and a commercial CFD code. Apart from the RANS method, which is commonly used i...

This paper presents a numerical analysis of the atmospheric air transonic flow through de Laval nozzles. By nature, atmospheric air always contains a certain amount of water vapor. The calculations were made using a Laval nozzle with a high expansion rate and a convergent-divergent (CD) “half-nozzle”, referred to as a transonic diffuser, with a muc...

In Poland more than 40% of the power units have been operating for over 40 years now and more than 10% are over 50 years old, which indicates a high degree of decrease in the value of the energy sector. An analysis of the energy market shows that every year a new power plant should be built with a capacity of 1000 MW to ensure the national energy s...

During the flow of atmospheric air through convergent-divergent (CD) nozzles the water vapour contained in it can condense spontaneously. The resulting liquid phase may then undergo further phase transitions, e.g. evaporation on the shock waves arising in the nozzle divergent part. The subject of this paper is a numerical and experimental analysis...

This article presents a validation study of the labyrinth seal testing. Both experimental and numerical simulations are performed. Literature data focused on simple labyrinth seals are surveyed, and two different configurations widely described in literature are investigated: a labyrinth seal with two straight fins against a smooth and a honeycomb...