Papers by Włodzimierz Wróblewski
Dissolved air effects on three-phase hydrodynamic cavitation in large scale Venturi- Experimental/numerical analysis
Ultrasonics Sonochemistry
Analiza sprawności obiegu cieplnego ultra-nadkrytycznego bloku kondensacyjnego dla szeregowej konfiguracji skraplaczy
Determination of interaction between thermal cycle and cooling water system of a supercritical power plant
Energies, 2021
Flow over a cavity or a gap may induce pressure fluctuations that are emitted as sound waves and ... more Flow over a cavity or a gap may induce pressure fluctuations that are emitted as sound waves and perceived by a human as noise. This phenomenon may occur in different kinds of industrial machines or in everyday life devices, e.g., cars. For this reason, it is important to predict the flow conditions that intensify or attenuate the noise. This research paper presents the numerical and experimental analysis of the pressure fluctuations in a deep, ducted cavity. The experimental test stand made it possible to investigate the flow over a cavity with air velocity in the range of 30–80 m/s. The pressure fluctuations were measured using miniature microphones located in the duct and the cavity wall and processed with LabView software. The phenomena were also analysed using the computational fluid dynamics (CFD) technique. The several modelling approaches were tested and validated against the experimental data. The highest sound pressure levels were obtained for 40 and 70 m/s. The sound freq...
European Conference on Turbomachinery Fluid Dynamics and hermodynamics, 2017
This article presents a validation study of the labyrinth seal testing. Both experimental and num... more 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 land and a seal with three straight fins against a smooth land only. For experimental testing the vacuum-feeding test rig is used, with the high-precision Hot Wire Thermoanemometry method applied for the mass flow evaluation. The dimensions of specimens described in literature are adapted to the in-house test rig conditions, meeting all the geometrical requirements mentioned by the author. The computational method is based on the Reynolds Averaged Navier Stokes scheme, with various turbulence models. The results of the simulations show good agreement with the in-house experiment, whereas some discrepancies are found compared to literature data.
Solving AeroAcoustics (CAA) problems by means of the Direct Numerical Simulation (DNS) or even th... more Solving 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 purposes. In this paper 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 non-linearized Euler equations for fluctuating (acoustic) variables. These codes are used to solve the pressure waves generated aerodynamically by a flow over a rectangular cavity and by the vortex street behind a turbine blade. The obtained results are discussed with respect to the application of the presented numerical techniques to pressure waves modeling in steam turbine stages.
Journal of Physics: Conference Series, 2014
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.
Modelowanie przepływu w olejowym separatorze turbinowego silnika lotnicznego
Modelowanie Inżynierskie, 2019
Transactions of the Institute of Fluid-Flow Machinery, 2017
This paper presents a preliminary, numerical what-if analysis of selected geometrical parameters ... more This paper presents a preliminary, numerical what-if analysis of selected geometrical parameters of the tip seal of the last stage of an aircraft engine turbine and the impact of the parameters on the leakage mass ow. The analysis is a part of the task of improving the rotor tip seal conguration in aircraft turbines. Calculations were carried out using the commercial computational uid dynamics code. A straight-through seal with two leaning ns and a honeycomb land was analysed. The computational model was prepared based on some simplications introduced to improve the eciency of the calculations. The rotor entire blade-to-blade channel was analysed, while the seal pitch was reduced to the dimensions of two honeycomb cells. The geometry of the ns themselves was simplied too. In the original variant, the n tips had caps to protect them from wear (shape deformation) due to rubbing. In the simplied model, the caps were omitted. The simplications did not change the leakage mass ow signicantly. Several variants of changes in the basic geometrical parameters of the seal were analysed to assess their eect on the leakage mass ow for altered ow conditions. Parameters such as the n thickness, the n inclination angle and the position of the ns and of the entire labyrinth were analysed. The best seal variant was selected, the ow phenomena were commented on and some points in the design of this type of the labyrinth seal were discussed.
Numerical simulation of the blade cascade flows using upwind methods
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk, 1998
Journal of Theoretical and Applied Mechanics, Jul 15, 2019
A numerical and experimental investigation of the Tesla turbine is presented in the paper. The ex... more A numerical and experimental investigation of the Tesla turbine is presented in the paper. The experiment is conducted for various inlet pressure and load. The roughness of the rotor disc is determined as it is a key factor to obtain high turbine efficiency and power. The numerical investigations are performed for the same conditions as in the experiment. The computational results are compared with the analytical model. Comparison of performance characteristics show a relatively good agreement between the experiment and CFD. The analytical model overestimates distributions of pressure and circumferential velocities, although the predicted power is on the similar level as in the experiment and CFD.
Sprzężony model obiegu cieplnego i układu wody chłodzącej dla siłowni na parametry nadkrytyczne
Rynek Energii, 2008
E3S web of conferences, 2019
The subject of this publication is the identification of basic flow parameters and flow structure... more The subject of this publication is the identification of basic flow parameters and flow structures in the seal experimentally and compare them with CFD results. A straight-through seal with two leaning fins and smooth or honeycomb land was analysed. The sealing concept is characteristic for the tip seal of the last stage of an aircraft low-pressure turbine. Due to the limitations of the test rig the analyses presented here were conducted on a highly simplified, stationary model of the seal itself, with an axial inflow and no curvature in the circumferential direction. The characteristics of the discharge coefficient as a function of the pressure ratio for different clearances and the pressure distribution along the seal, for different pressure ratios are presented. In addition, an attempt was made to visualize the flow using the schlieren technique. The main idea of application schlieren photography was to observe the vortex and separation structures occurring during the flow through the labyrinth seal, which is the major source of pressure losses. CFD calculations were carried out using the Ansys CFX commercial code.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk, 2006
The aim of this work is to estimate the losses in steam flow through an LP steam turbine rotor an... more The aim of this work is to estimate the losses in steam flow through an LP steam turbine rotor and the whole stage. Two types of losses occur in steam flow, aerodynamic (profile, secondary flow, leakage) and thermodynamic (due to addition of heat caused by condensation). The presented numerical results are split into two groups. First, a comparison of three different calculation methods of steam flow is carried out. To this end, the geometry of an LP steam turbine's last rotor is chosen. The first examined method is the Streamline Curvature Method (SCM) used on the meridional plane with loss correlations, the other two being commercial and in-house CFD codes, solving the Reynolds-averaged Navier-Stokes equations for a 3D flow. The first two codes model equilibrium steam properties below the saturation line, while the latter models non-equilibrium steam properties. Finally, a comparison is made of the influence on loss prediction of various condensation models for the geometry of the penultimate stage, with the use of an in-house CFD code.
Journal of physics, Oct 1, 2018
Tesla turbine is a bladeless turbine and its principle of operation is based on shear stress aris... more Tesla turbine is a bladeless turbine and its principle of operation is based on shear stress arising from fluid viscosity and turbulence. A prototype of Tesla turbine is an object of numerical and experimental investigations presented in the paper. Experimental investigations were carried out for different inlet pressures and compared to results from numerical investigations. The roughness of the disc surface was measured and taken into account in the numerical analysis. Numerical investigations were performed in CFX 17.1 commercial software for steady state and transient. Comparison of power and efficiency vs rotational velocity characteristics shows relatively good agreement between experiment and CFD.
Modelowanie kawitacji przy opływie profilu z zastosowaniem zmiennej liczby kawitacji
Modelowanie Inżynierskie, 2015
Efficiency based optimization of a Tesla turbine
Energy, Dec 1, 2021
Abstract Tesla turbine is a bladeless, radial turbine which might be suitable for the application... more Abstract Tesla turbine is a bladeless, radial turbine which might be suitable for the applications in various energy systems, e.g. in Organic Rankine Cycle or combined heat and power systems if its efficiency improves. The investigations presented in the paper concern efficiency based numerical optimization of a Tesla turbine. Parameters subjected to the optimization process are inlet nozzle height, inter-disc gap, nozzle angle, pressure and rotational velocity. The optimization was conducted using response surface methodology. The first stage of the optimization excluded pressure ratio as neutral to efficiency. The second stage of the optimization allowed determination of the most important parameters: tangential velocity ratio, partial admission coefficient, reaction degree and aspect ratio required for maximization of the turbine's efficiency. Efficiency was improved almost twice with the respect to the nominal model (from 9% to 17%) and validated experimentally. Performance characteristics of the optimized turbine model were calculated using computational fluid dynamics software.
Przepływy dwufazowe w układach łopatkowych turbin parowych
Calculations of the condensing water steam flows in turbine blade cascades
11<sup>th</sup> European Conference on Turbomachinery Fluid dynamics & Thermodynamics, 2015
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Papers by Włodzimierz Wróblewski