David Šimurda
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View article: Aerodynamic response of a blade cascade to torsional excitation of one blade at subsonic and transonic velocities
Aerodynamic response of a blade cascade to torsional excitation of one blade at subsonic and transonic velocities Open
The trend of increasing the power-to-weight ratios of aircraft turbofan engines and efficiency of steam turbines leads to designs with long and slender blades often operating at transonic flow conditions. Such blades are prone to undesirab…
View article: Data Reduction Methods in Turbomachinery Linear Blade Cascade Experiment
Data Reduction Methods in Turbomachinery Linear Blade Cascade Experiment Open
The work explores data reduction methods used in turbomachinery linear blade cascade experiment, such as area and mass averaging and Two-Dimensional Momentum Method, and their properties. Definitions of the most common methods are listed a…
View article: Hybrid LES/RANS Simulations of Compressible Flow in a Linear Cascade of Flat Blade Profiles
Hybrid LES/RANS Simulations of Compressible Flow in a Linear Cascade of Flat Blade Profiles Open
The paper reports on 3D numerical simulations of unsteady compressible airflow in a blade cascade consisting of flat profiles using a hybrid LES/RANS approach including a transition model. As a first step towards simulation of blade flutte…
View article: Computational study of flow separation in truncated ideal contour nozzles under high-altitude conditions
Computational study of flow separation in truncated ideal contour nozzles under high-altitude conditions Open
Flow separation in rocket nozzles has been studied mostly under sea-level conditions, which fail to take into account changes in ambient density and ambient pressure during the flight of a rocket. In the present study, numerical analysis i…
View article: On Linear Modelling of Axial Velocity Density Ratio Development in Compressor Blade Cascades
On Linear Modelling of Axial Velocity Density Ratio Development in Compressor Blade Cascades Open
Flow field in transonic compressor blade cascade is examined by means of numerical simulations. Quasi-3D simulations with an influence of axial velocity density ratio (AVDR) are performed. Results of the simulations are compared to data av…
View article: Influence of elastic deformation of the blade on the flow field in the blade cascade
Influence of elastic deformation of the blade on the flow field in the blade cascade Open
Flutter of turbine and compressor blades represents a serious problem for designers of large turbomachines. In real machines, measurements of flutter conditions are hardly possible. Therefore, tests on linear blade cascades with movable bl…
View article: Shock wave configuration in a transonic flow through a mid-section of a last stage turbine blade cascade equipped with a part-span connector
Shock wave configuration in a transonic flow through a mid-section of a last stage turbine blade cascade equipped with a part-span connector Open
This paper deals with the study of a flow field and namely the configuration of shock waves in a blade cascade equipped with a part-span connector called tie-boss. The cascade consists of prismatic blades formed from the mid-section of a v…
View article: Investigation of the supersonic flow past a wedge-shaped geometry using pressure sensitive paints technique
Investigation of the supersonic flow past a wedge-shaped geometry using pressure sensitive paints technique Open
This study aims to present results of an investigation of the supersonic flow past a wedge-shaped geometry using the pressure sensitive paints technique (PSP). The wedge-shaped geometry was chosen as a canonical case for the investigation …
View article: Laser triangulation measurement of blade oscillation in a transonic compressor cascade
Laser triangulation measurement of blade oscillation in a transonic compressor cascade Open
The paper describes a method for optical measurement of oscillation of blades in a linear cascade designed for flutter research. The method uses laser triangulation, which measures the distance between the sensor and the oscillation object…
View article: Blade pressure loading and torque measurement in a transonic linear cascade
Blade pressure loading and torque measurement in a transonic linear cascade Open
Experimental results of a transonic compressor blade pressure loadings and blade shaft torque measurements are presented in this paper. Data were acquired for the cascade middle blade being set to a number of incidence angle offsets to sim…
View article: Two-wavelength interferometry for measurement of transonic airflow in a compressor blade cascade
Two-wavelength interferometry for measurement of transonic airflow in a compressor blade cascade Open
This paper presents high-speed two wavelength interferometry for measuring fast phenomena, which allows to extend the dynamic range of measurement using two different wavelengths at the same time. The method was applied to measure transoni…
View article: Impact of steam erosion on aerodynamic characteristics of the tip section of a long rotor turbine blade
Impact of steam erosion on aerodynamic characteristics of the tip section of a long rotor turbine blade Open
Results of aerodynamic research on original variant of tip section are compared with aerodynamic data obtained from research on eroded variant. The erosion of the inlet part of the profiles generates serious changes both in profile shape a…
View article: Valve seat angle influence on losses in valves for steam turbines
Valve seat angle influence on losses in valves for steam turbines Open
Losses in valve assemblies have a significant influence on turbines´ efficiency. Therefore, performing pressure loss analysis to enhance the valve design has always been one of the traditional issues. Valves can differ in many ways in term…
View article: Pressure Losses Downstream of a Compact Valve in the Inlet Chamber of an Intermediate-Pressure Steam Turbine
Pressure Losses Downstream of a Compact Valve in the Inlet Chamber of an Intermediate-Pressure Steam Turbine Open
Deep knowledge about pressure and energy losses in each part of a steam turbine is crucial for assuring the required efficiency and operational reliability. This paper presents the experimental as well as the numerical study of pressure lo…
View article: Optical and Hot-Film Measurements of the Boundary Layer Transition on a Naca Airfoil
Optical and Hot-Film Measurements of the Boundary Layer Transition on a Naca Airfoil Open
This study explores the possibilities of identifying position of a boundary layer transition using hot film measurements complemented by classical optical methods i.e. interferometry and schlieren method. The subject of the measurement is …
View article: Study on Losses in the Intermediate-Pressure Steam Turbine Inlet Chamber
Study on Losses in the Intermediate-Pressure Steam Turbine Inlet Chamber Open
Know-how about energy and pressure losses in all steam turbine parts is crucial to guarantee enhanced operational reliability and efficiency. This paper focuses on studying pressure losses in the intermediate-pressure turbine inlet chamber…
View article: CFD Investigation of the test facility for forced blade flutter research
CFD Investigation of the test facility for forced blade flutter research Open
With the increasing share of renewable power resources turbomachines need to be operated under a wider range of operating conditions including highly off-design regimes. Under such regimes an undesirable phenomenon of blade flutter might o…
View article: On the possible origin of a vapour cone occurring during the transonic flight in moist air
On the possible origin of a vapour cone occurring during the transonic flight in moist air Open
In aerodynamics as in other sciences, there are some phenomena which are widely explained in a way that under a closer look turns out to be based on wrong assumptions and thus not very convincing. One of these is the effect referred to as …
View article: Aerodynamic and dynamic loading in a blade cascade designed for flutter research
Aerodynamic and dynamic loading in a blade cascade designed for flutter research Open
Flow-induced vibration of turbine and compressor blades, so called blade flutter, represents a serious problem for designers and operators of large turbomachines. The research of mechanisms leading to this dangerous aeroelastic instability…
View article: Measurement of Unsteady Aerodynamic Data in Turbomachi-nery Periodic Flows
Measurement of Unsteady Aerodynamic Data in Turbomachi-nery Periodic Flows Open
The objective of this work is to demonstrate the feasibility and advantage of an alternative approach to aerodynamic data acquisition in high-speed highly-loaded turbine engine rotating components. Two methodologies of data acquisition usi…
View article: Investigation of Transonic Flow Through Linear Cascade with Single Blade Incidence Angle Offset
Investigation of Transonic Flow Through Linear Cascade with Single Blade Incidence Angle Offset Open
The contribution deals with numerical and experimental investigation of the effect of incidence angle offset in a two-dimensional section of a flat linear blade cascade in a high-speed wind tunnel. The aim of the work is to complement ongo…
View article: Pressure losses reduction in a steam turbine compact valve
Pressure losses reduction in a steam turbine compact valve Open
Valves are integral parts of modern steam turbines. They provide flexible operations and fast load changes which have become more often due to the increasing share of renewable energy. Along with this, the low pressure loss is required for…
View article: Characterization of Supersonic Compressible Fluid Flow Using High-Speed Interferometry
Characterization of Supersonic Compressible Fluid Flow Using High-Speed Interferometry Open
This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in a wind tunnel facility. The developed technique is very sensitive and accurate, yet easy to use under conditions typi…
View article: Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade
Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade Open
The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerody…
View article: Verification tests of a new blade flutter research facility
Verification tests of a new blade flutter research facility Open
Long term strategic changes in power generation approaches will require more flexibility for large power generating turbines as an unavoidable consequence of the increasing share of power generated by alternative energy sources. Demanded f…
View article: Pressure losses and oscillations in a compact valve of a steam turbine
Pressure losses and oscillations in a compact valve of a steam turbine Open
Characteristics of a new compact valve design for steam turbines are analysed by measuring pressure losses and oscillations on the valve model. It is the model of an intercept valve of the intermediate-pressure turbine part. This valve is …
View article: Comparison of Transonic Flows Through Two Tip-Section Turbine Blade Cascades with Different Flat Profiles
Comparison of Transonic Flows Through Two Tip-Section Turbine Blade Cascades with Different Flat Profiles Open
The contribution deals with numerical simulations of 2D compressible flow through two variants of the tip-section turbine blade cascade with a flat profile for the subsonic inlet.Simulations were realised by means of the OpenFOAM code usin…
View article: New test facility for forced blade flutter research
New test facility for forced blade flutter research Open
Blade flutter problems will become more serious in the near future for large power generating turbines as unavoidable consequences of the increasing share of power generated by renewable energy sources. The Institute of Thermomechanics of …
View article: Turbine Cascades of Last Stage Blades for Wide Range of Operating Conditions
Turbine Cascades of Last Stage Blades for Wide Range of Operating Conditions Open
Recent trends in the electric energy market such as biomass, waste incineration or combined cycle power plants require innovative solutions in steam turbine design. Variable operating conditions cause significant changes in flow field surr…