49 results on '"Martin Luxa"'
Search Results
2. REGARDING CERTAIN AERODYNAMIC SOURCES OF NON-STATIONARY FORCE LOADS ON TURBINE PROFILES
- Author
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Tomáš Radnic, Martin Luxa, and David Šimurda
- Subjects
turbine blade cascade, unstarted supersonic flow, swirl line, off design conditions ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The paper deals with selected phenomena present in a blade cascade flow field. The presented research was performed on prismatic blade cascades composed mostly of the tip and root sections of the last stage rotor blade of a large output steam turbine. The unstarted supersonic flow on the cascade inlet, the separation of the flow and the swirl line behind the trailing edge have been identified as the possible sources of the unsteady force effects.
- Published
- 2018
- Full Text
- View/download PDF
3. Characterization of Supersonic Compressible Fluid Flow Using High-Speed Interferometry
- Author
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Pavel Psota, Gramoz Çubreli, Jindřich Hála, David Šimurda, Petr Šidlof, Jan Kredba, Marek Stašík, Vít Lédl, Michal Jiránek, Martin Luxa, and Jan Lepicovsky
- Subjects
high-speed ,interferometry ,supersonic ,compressible flow ,wind tunnel ,Chemical technology ,TP1-1185 - Abstract
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 typical for aerodynamic labs, and will be used for the nonintrusive investigation of flutter in blade cascades. The interferometer employs a high-speed camera, fiber optics, and available “of-the-shelf” optics and optomechanics. The construction of the interferometer together with the fiber optics ensures the high compactness and portability of the system. Moreover, single-shot quantitative data processing based on introducing a spatial carrier frequency and Fourier analysis allows for almost real-time quantitative processing. As a validation case, the interferometric system was successfully applied in the research of supersonic compressible fluid discharge from a narrow channel in a wind tunnel. Density distributions were quantitatively analyzed with the spatial resolution of about 50 μm. The results of the measurement revealed important features of the flow pattern. Moreover, the measurement results were compared with Computational Fluid Dynamics (CFD) simulations with a good agreement.
- Published
- 2021
- Full Text
- View/download PDF
4. Turbine Cascades of Last Stage Blades for Wide Range of Operating Conditions
- Author
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Ondrej Novak, Marek Bobcik, Martin Luxa, Jaroslav Fort, Bartolomej Rudas, Jaroslav Synac, David Simurda, Jiri Furst, Jan Halama, Vladimir Hric, Jaromir Prihoda, and Zdenek Simka
- Subjects
turbine ,cascade ,last stage blade ,CFD ,experimental validation ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
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 surrounding the steam turbine last stage blades. Therefore, the enlargement of operating range for last stage blades presents new challenges in design of turbine cascades. Several turbine cascades were designed and analyzed by commercial and in-house software of CTU Prague. Selected profiles were experimentally validated in the high-speed wind tunnel for 2D cascade measurements of the Institute of Thermomechanics of the Czech Academy of Sciences which is equipped by an adjustable supersonic inlet nozzle, perforated inserts at side walls and adjustable perforated tailboard. Comparisons are presented of numerical results with optical and pneumatic measurements for a wide range of inlet and outlet Mach numbers for optimized hub and tip profile cascades.
- Published
- 2019
- Full Text
- View/download PDF
5. Causes and Solution of Aperiodicity of Supersonic Flow Field Downstream of a Profile Cascade
- Author
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Martin Luxa, Jaroslav Synac, Pavel Safarik, and David Simurda
- Subjects
turbine cascade ,exit flow periodicity ,transonic flow ,porous tailboard ,limit load ,Transportation and communications ,HE1-9990 ,Science ,Transportation engineering ,TA1001-1280 - Abstract
The paper deals with problems of transonic flow field periodicity downstream of a profile cascade with finite number of blades. The origin of phenomena generating this aperiodicity in transonic wind tunnel is described. The solution of this problem by means of adjustable perforated tailboard is documented by results of optical measurements (interferometry, schlieren methods) on a turbine profile cascade consisting of six blades only. The conditions of formation of limit load regime are described.
- Published
- 2012
- Full Text
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6. AERODYNAMIC RESEARCH ON THE MIDSECTION OF A LONG TURBINE BLADE
- Author
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DAVID SIMURDA, MARTIN LUXA, PAVEL SAFARˇ´IK, and JAROSLAV SYNA´C
- Subjects
transonic flow ,turbine blade cascade ,experimental research ,Information technology ,T58.5-58.64 - Abstract
The paper is concerned with experimental aerodynamic research on the midsection of a 1220 mm long turbine rotor blade. Optical as well as pneumatic measurements of the midsection blade cascade have been performed in a suction type high-speed wind tunnel. The results of measurements are analyzed and discussed. Interferograms and schlieren pictures taken in a wide range of isentropic exit Mach numbers and incidence angles exhibit the existence of several phenomena occurring in the transonic flow field at certain conditions concerning the exit Mach number and the angle of incidence. A flow separation taking place at an extreme negative incidence has been found to produce an additional loss of 6%. The presence of the reflection of an exit shock wave on the suction side of the neighbouring profile has been found to have a substantial influence on the losses, since the loss coefficient value has increased about 10% in cases without the reflection, i.e. the cases at a high exit Mach number and a high positive angle of incidence. Several reflection types have been observed and described.
- Published
- 2008
7. Optical measurement and visualization of transonic airflow in a compressor blade cascade.
- Author
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David Simurda, Pavel Psota, Petr Sidlof, Robert Kielb, Martin Luxa, Jindrich Hála, and Jan Lepicovsky
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- 2023
- Full Text
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8. Numerical simulation of flow through cascade in wind tunnel test section and stand-alone configurations.
- Author
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Jaroslav Fort, Jirí Fürst, Jan Halama, Vladimír Hric, Petr Louda, Martin Luxa, and David Simurda
- Published
- 2018
- Full Text
- View/download PDF
9. Optical measurement and visualization of transonic airflow in a compressor blade cascade
- Author
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David Šimurda, Pavel Psota, Petr Šidlof, Robert Kielb, Martin Luxa, Jindřich Hála, and Jan Lepicovsky
- Subjects
Electrical and Electronic Engineering ,Condensed Matter Physics - Published
- 2022
10. The measuring of contra rotating propellers with different diameters and design points
- Author
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Jan Mixa, Martin Luxa, and Michal Schmirler
- Published
- 2023
11. Exploratory Experiments for Simple Approximation of Blade Flutter Aerodynamic Loading Function
- Author
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Jan Lepicovsky, David Simurda, Petr Sidlof, and Martin Luxa
- Abstract
Exploratory experiments to verify a newly proposed simple method determining an approximate form of unsteady blade loading function are described in this paper In this newly proposed approach, a time-dependent blade loading will be substituted for by a series of static loadings acquired for a range of blade incidence angle offsets. The sequence of static loadings will be converted into a time-dependent quasi-dynamic function computationally. In the course of this project a new test facility for forced blade flutter research capable of transonic inlet flow at high oscillation blade frequencies was designed and built at the IT CAS laboratory. A series of test runs simulating blade flutter conditions were carried out for the inlet Mach number range from 0.6 up to 1.09 and blade oscillation frequencies up to 80 Hz. A blade static loading function was created as a pressure difference measured while the blade was not moving and it was set to the outermost incidence angle offsets of plus/minus 1 deg. A blade dynamic loading function was determined as a peak-to-peak amplitude of measured pressure fluctuation while the blade was oscillated at a frequency of 80 Hz. A very good agreement between the measured blade static and blade dynamic loading functions indicates the potentials of the proposed quasi-dynamic method to closely estimate blade loading functions, at least for the reported range of cascade operation conditions.
- Published
- 2022
12. Pressure Losses Analysis in Two High-Pressure Steam Turbine Control Valves Situated in One Valve Chamber
- Author
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Vaclav Slama, Bartolomej Rudas, David Simurda, Jindrich Hala, and Martin Luxa
- Abstract
Steam turbines belong to the most important systems in power conversion. In order to control their power output at steady state base load or part load conditions, the use of control valves is a widely used method. The flow in a pair of high-pressure steam turbine control valves which are situated in one valve chamber is analyzed in this paper from the pressure losses point of view. The experiments were carried out on a valve model installed in a wind tunnel for high speeds in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences. The flow at different valve cone lifts in both control valves was investigated and results were generalized in the form of so-called valve characteristics. Investigations were carried out on the model with control valve strainers and without them. In order to further understand the reasons of detected pressure loss differences, the numerical simulations were carried out in the Doosan Skoda Power Company using ANSYS software tools. The comparison of results shows which cases of the valve setup are preferable with regard to pressure losses and thus efficiency. Furthermore, an existing pressure loss prediction model for valve pressure loss estimation for each investigated case was updated. This model helps to better design the valve geometry in order to increase overall turbine efficiency.
- Published
- 2022
13. Near-Wall Flow in the Blade Cascades Representing Last Rotor Root Sections of Large Output Steam Turbines
- Author
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Martin Luxa, David Šimurda, Ondřej Novák, Jindřich Hála, Jaroslav Synáč, Marek Bobcik, and Jiří Fürst
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Materials science ,business.industry ,Rotor (electric) ,020209 energy ,Flow (psychology) ,02 engineering and technology ,Aerodynamics ,Mechanics ,Computational fluid dynamics ,Condensed Matter Physics ,Secondary flow ,law.invention ,Physics::Fluid Dynamics ,symbols.namesake ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Mach number ,law ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,business ,Reynolds-averaged Navier–Stokes equations ,Choked flow - Abstract
This paper investigates the flow past two variants of root section profile cascades for a last stage rotor considering three-dimensional flow structures in the near-wall region. Analyses were drawn based on RANS numerical simulations of both variants and on the experimental data obtained by the 3D traversing in the exit flow field of one of the variants. Extent of 3D structures at two different regimes and its influence on aerodynamic characteristics of the blade cascades was assessed. The distributions of Mach number along the profiles were compared with 2D optical measurements and its distortion due to the presence of the sidewall was explored. The interaction between main vortical structures was described and its influence on the loading of the blades, mechanical energy losses and exit flow angle was discussed. The results showed that for a front loaded blade the vortical structures appeared earlier and at a larger extent than for an aft loaded variant. However, due to different Mach number distribution, contribution of end wall flow to the energy losses was lower in the case of the aft loaded variant. The influence of the near wall flow on the loading was found to be rather weak while the deviation of the exit flow angle appeared to be comparable for both of the variants.
- Published
- 2020
14. Development of Loss Correlation and Tool Validation at Transonic Condition Based on Cascade Test
- Author
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Jan Lepicovsky, Martin Luxa, David Šimurda, Jindrich Hala, Jaewook Song, Tomáš Radnic, Junhyuk Seo, Jaewoo Choi, and Sungryong Lee
- Subjects
Correlation ,Control theory ,Computer science ,Cascade ,Transonic ,Test (assessment) - Abstract
Overall efficiency of an axial compressor is largely affected by its front stage when it is operating under transonic flow conditions. For this reason, many manufacturers and researchers are advancing research and development of transonic airfoils in these days. Doosan, in frame of a development of high efficiency gas turbine, developed high efficiency airfoil for a transonic rotor and conducted cascade tests. Therefore, this study deals with a test of two compressor transonic blade cascades at inlet Mach number over 1.1. To improve the efficiency and operating range, two kinds of thickness distribution type based on Enhanced Doosan Airfoil (EDA), which applied unique rule, were applied and assessed. The first airfoil consists of polynomial thickness distribution and the second airfoil consists of new thickness distribution with specially tailored leading edge. In order to ensure accurate geometry of a model, a detailed checkout process upon production of model blades used in the test was performed. This is because, in the case of transonic airfoil, if the inlet leading edge shape differs by more than 0.2% than designed airfoil of leading edge, the result will be completely different. Therefore, not only the tolerance within 0.1% was confirmed but also the shape produced through simulation and 3D CMM scan data. The main parameters for the comparison are an inlet Mach number, an axial velocity density ratio (AVDR) and the kind of thickness distribution. Results of tests and CFD blade to blade analysis using MISES 2.70 are compared. The flow field was visualized using schlieren technique and parameters of the suction side boundary layer were evaluated at several locations based on Pitot probe traverses. The results confirm that a suction peak at the round leading edge disappears in the case of the new thickness type distribution with tailored leading edge. This confirms that the profile shaping without jump in curvature in the leading edge region leads to smooth acceleration without peaks. Nevertheless, results show that the new thickness distribution type is not absolutely good in comparison with the polynomial thickness distribution type with respect to the total pressure loss coefficient. Moreover, bucket range (operating range) is also almost the same. Results of the suction side boundary layer traversing suggest that the transition of the boundary layer takes place beyond the location x/cax > 0.088. The MISES results show that a shock location and the boundary layer parameters are similar to test results. However, values of the loss coefficient show some difference. Therefore, a new correlation in particular transonic flow condition was developed.
- Published
- 2021
15. REGARDING CERTAIN AERODYNAMIC SOURCES OF NON-STATIONARY FORCE LOADS ON TURBINE PROFILES
- Author
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Martin Luxa, David Šimurda, and Tomáš Radnic
- Subjects
Rotor (electric) ,Flow (psychology) ,Aerodynamics ,Mechanics ,Turbine ,law.invention ,turbine blade cascade, unstarted supersonic flow, swirl line, off design conditions ,lcsh:TA1-2040 ,law ,Steam turbine ,Cascade ,General Earth and Planetary Sciences ,Trailing edge ,lcsh:Engineering (General). Civil engineering (General) ,Choked flow ,Geology ,General Environmental Science - Abstract
The paper deals with selected phenomena present in a blade cascade flow field. The presented research was performed on prismatic blade cascades composed mostly of the tip and root sections of the last stage rotor blade of a large output steam turbine. The unstarted supersonic flow on the cascade inlet, the separation of the flow and the swirl line behind the trailing edge have been identified as the possible sources of the unsteady force effects.
- Published
- 2018
16. Comparison of Transonic Flows Through Two Tip-Section Turbine Blade Cascades with Different Flat Profiles
- Author
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Martin Luxa, Josef Musil, David Šimurda, Jiří Fürst, and Jaromír Příhoda
- Subjects
Turbine blade ,Section (archaeology) ,law ,Mechanics ,Transonic ,Geology ,law.invention - Published
- 2021
17. Numerical investigation of 3-D flow phenomena in interblade channel with tie-boss
- Author
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Tomáš Radnic, Šimurda David, Martin Luxa, and Jindřich Hála
- Subjects
Physics ,Boss ,Rotor (electric) ,law ,Steam turbine ,Cascade ,Flow (psychology) ,Trailing edge ,Mechanics ,Aerodynamics ,law.invention ,Vortex - Abstract
The paper is concerned with numerical investigation of 3-D flow field in a last stage rotor blading in a steam turbine of large power output. The mid-span section of 1220 mm long blade is equipped with a stabilization device called tie-boss, two variants of which have been investigated. The tie-boss presents considerable disruption to the flow field and is a reason of loss of efficiency and origin of vortices. The investigation has been conducted in Ansys CFX. Detailed investigation determined origins of vorticial structures and identified separations, which have non-negligible effect on the aerodynamic parameters of the blade cascade. The research allows comparison of the quality of the flow field of both tie-boss variants. The results show that the tie-boss with round trailing edge causes lower loss coefficient increase and higher exit flow angle change than the variant with tailored trailing edge.
- Published
- 2021
18. New test facility for forced blade flutter research
- Author
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Martin Luxa, Jan Lepicovsky, David Šimurda, Martin Štěpán, and Petr Šidlof
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Engineering ,Test facility ,Blade (geometry) ,Aeronautics ,business.industry ,Flutter ,Thrust ,Aerodynamics ,business ,Transonic - Abstract
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 the Czech Academy of Sciences (IT CAS) was awarded a grant to initiate a blade flutter research program. The main thrust of the IT CAS role in this program is to pursue advancements in experimental technique applications and to establish a reliable experimental database of blade mutual aerodynamic interactions during the blade flutter onset for the sonic and transonic flow regimes in particular. A new sophisticated test section for transonic blade flutter research was designed and being manufactured to fulfill such requirements. Experience gained while working with the NASA Transonic Flutter Cascade facility resulted in new innovative features included in the new design. The new facility will be delivered to the High-Speed Laboratory in Novy Knin by the end of September 2020.
- Published
- 2021
19. Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System
- Author
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Jindrich Hala, Bartolomej Rudas, Václav Sláma, David Šimurda, Martin Luxa, and Lukáš Mrózek
- Subjects
Pipeline transport ,Flow instability ,Reliability (semiconductor) ,Steam turbine ,Nozzle ,Flow (psychology) ,Computer software ,Environmental science ,Relief valve ,Marine engineering - Abstract
Aerodynamic measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for nozzle governing of a turbine with 135MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field. It is an important task since undesirable flow fluctuations can lead to operational reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences (IT) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operating points. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve’s strainers, which were historically used in order to stabilize the flow, and without them. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From measured pressure fluctuations, it was found out where and for which conditions a danger of flow instabilities occurs. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve’s strainers are used or not. Therefore, the areas of safe and danger operational reliability can be predicted. The influence of the control valve’s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are highly overloaded. For normal operating conditions, there is no difference. As a result, the control valve’s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid with similar valve assemblies.
- Published
- 2020
20. Pressure losses reduction in a steam turbine compact valve
- Author
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Vaclav Slama, David Simurda, Ladislav Tajc, Bartolomej Rudas, Jindrich Hala, Martin Luxa, and Tomas Radnic
- Abstract
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 guaranteed operation conditions. This paper is concerned with investigation of pressure losses in the compact valve, which is used as a valve for the intermediate-pressure turbine part, and its geometry modification to lower overall pressure losses. The investigation is based on results of numerical simulations which were carried out in the Doosan Skoda Power Company using a package of ANSYS software tools. Source of increased pressure losses in the compact valve is identified and a way of its reduction is proposed based on the comparison of the current results with data from a typical control valve model. Data analysis is provided in the paper.
- Published
- 2022
21. CFD Simulation of Transonic Flow Through the Tip-Section Turbine Blade Cascade Intended for the Long Turbine Blade
- Author
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Pavlo Kosiak, Jindřich Hála, Martin Luxa, and Jaromír Příhoda
- Abstract
The paper deals with numerical simulations of transonic flow through the turbine blade cascade consisting of flat profiles. The cascade is one of variants of the tip section of ultra-long blades, which were designed for the last stage of the steam turbine. CFD simulations were realized by means of the ANSYS CFX commercial software using the γ-Reθ bypass transition model completed by the two-equation SST turbulence model. Some simulations were made only by the SST turbulence model for comparison. Numerical results were compared with experimental data. Calculations performed for two nominal regimes and two computational domains. In addition to the standard computational domain, the calculation was performed for a domain with an extended output part for the suppression of reflected shock waves. The interaction of the inner branch of the exit shock wave with the boundary layer on the blade suction side leads in the both flow regimes to the flow separation followed by the transition to turbulence. The flow structure in the blade cascade obtained for the extended domain corresponds well to experimental results.
- Published
- 2022
22. Optical and Hot-Film Measurements of the Boundary Layer Transition on a Naca Airfoil
- Author
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David Šimurda, Jindřich Hála, Martin Luxa, and Tomáš Radnic
- Abstract
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 a NACA 0010-64 airfoil with varying leading edge surface quality corresponding to smooth surface and rough surface with Ra ~ 50 and Ra ~ 100. Measurements are performed at several subsonic regimes and a transonic regime. Despite several shortcomings of the experimental setup, the method proved to be useful in providing information on the boundary layer transition. Measurements show that in the case of smooth leading edge, the onset of the boundary layer transition shifts upstream with increasing inlet Mach number and the major portion of the boundary layer is transitional. This is in accordance with other published results on the boundary layer transition on this kind of airfoils [1]. In all cases with the rough leading edge, the complete transition takes place on the rough portion of the surface already.
- Published
- 2022
23. Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade
- Author
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David Šimurda, Martin Luxa, Bartoloměj Rudas, Ondřej Novák, Jaroslav Synáč, Jindřich Hála, and Marek Bobcik
- Subjects
business.industry ,Rotor (electric) ,020209 energy ,030206 dentistry ,02 engineering and technology ,Aerodynamics ,Structural engineering ,Condensed Matter Physics ,Dovetail joint ,law.invention ,03 medical and health sciences ,symbols.namesake ,0302 clinical medicine ,Mach number ,law ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Trailing edge ,Limit load ,Supersonic speed ,business ,Transonic ,Mathematics - Abstract
This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Mach number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements (optical and pneumatic).
- Published
- 2018
24. Numerical simulation of flow through cascade in wind tunnel test section and stand-alone configurations
- Author
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J. Fořt, David Šimurda, Martin Luxa, Petr Louda, Vladimír Hric, Jiří Fürst, and Jan Halama
- Subjects
Physics ,Finite volume method ,Shock (fluid dynamics) ,Turbulence ,Applied Mathematics ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Physics::Fluid Dynamics ,Computational Mathematics ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Cascade ,Hypersonic wind tunnel ,Supersonic speed ,0210 nano-technology ,Transonic ,Simulation ,Wind tunnel - Abstract
The paper deals with the numerical simulation of the flow field in a turbine cascade, which corresponds to the tip section of a last low-pressure steam turbine rotor. Considered cascade consists of very thin profiles with high stagger angle. The resulting flow field is complex with interactions of strong shock waves, shear layers and shock reflections. The paper proposes a proper numerical approximation of boundary conditions suitable for cases with supersonic inlet and outlet flow velocities and compares the flow field for two cascade configurations: the first one corresponding to real experiment (cascade with finite number of blades located in the wind tunnel test section) and the second one corresponding to annular cascade. The experimental configuration includes the complicated geometry of wind tunnel. The annular configuration leads to blade to blade periodicity, which is not guaranteed for the experimental configuration. Numerical simulations are based on the Favre-averaged Navier–Stokes equations with SST k – ω turbulence model and the in-house implicit finite volume solver with AUSM-type discretization. This method considers structured multi-block grid. Results are compared with experimental data.
- Published
- 2018
25. Development of Highly Efficient and Robust Ultra-Long Last Stage Blade for High Backpressure
- Author
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Ales Macalka, Jiri Ira, Antonin Zivny, David Šimurda, Bartolomej Rudas, Jan Hlous, Ondrej Novak, Martin Luxa, Vaclav Slama, Marek Bobcik, Zdenek Simka, Petr Mestanek, and Josef Kellner
- Subjects
Blade (geometry) ,Computer science ,Mechanical engineering ,Stage (hydrology) - Abstract
For modern steam turbines with large operating range and enhanced efficiency an ultra-long last stage rotor blade in a low pressure turbine part for high backpressure and 50 Hz fixed speed operation have been developed. An advanced design approach was used to create the blade shape with a high thermodynamic efficiency, high natural frequencies and a very high safety factor of average radial static stress in the blade span. Furthermore, the tip section of the bucket was improved to decrease a static tension and the hub section was refined to simplify the assembly. Tip and hub airfoils were experimentally validated in a supersonic wind tunnel. An advanced in-house procedure using numerical analysis to predict a potential danger of unstalled flutter was carried out for wide range of operating conditions.
- Published
- 2019
26. Nominal regimes of supersonic profile cascade
- Author
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Bartoloměj Rudas, Martin Luxa, Jiří Fürst, and Jaroslav Synáč
- Subjects
Physics ,Cascade ,Back pressure ,Technical university ,Mechanical engineering ,Supersonic speed ,Aerodynamics ,Ansys fluent ,Power (physics) ,Wind tunnel - Abstract
This article is concerned with the new design of supersonic profile cascade, marked TR-U-8, for ultra-long bucket tip area. The profile cascade represents a geometrical variant of the ultra-long bucket tip section which was designed in Doosan Skoda Power in Pilsen. There were found out outputs of two aerodynamic regimes marked OP1 India 800 MW for higher back-pressure and OP4 Temelin 1200 MW for lower back pressure. Outputs for nominal incidence cascade angle are presented in this paper. The design of cascades by aerodynamic calculations were investigated and validation by evaluation of optical and pneumatic measurements on wind tunnel tests was done. Two dimensional cascade calculations were carried out by commercial code Ansys Fluent 16.0 in Doosan Skoda Power (DSPW) and by non-commercial software developed in Czech Technical University (CTU). An aerodynamic high speed wind tunnel is located in Institute of Thermomechanics the Czech Academy of Science (AS CR).
- Published
- 2019
27. Investigation of the compressible flow through the tip-section turbine blade cascade with supersonic inlet
- Author
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Jaromír Příhoda, Martin Luxa, Petr Straka, Jaroslav Synáč, and David Šimurda
- Subjects
010302 applied physics ,geography ,Materials science ,geography.geographical_feature_category ,Blade (geometry) ,Turbine blade ,business.industry ,02 engineering and technology ,Mechanics ,Computational fluid dynamics ,Condensed Matter Physics ,Inlet ,01 natural sciences ,Compressible flow ,law.invention ,Cascade ,law ,Schlieren ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Supersonic speed ,business - Abstract
The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical (interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field.
- Published
- 2016
28. Aerodynamic Effects of Tie-Boss in Extremely Long Turbine Blades
- Author
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David Šimurda, Dan Hasnedl, Jiří Fürst, Jindřich Hála, Josef Kellner, Martin Luxa, and Tomáš Radnic
- Subjects
Turbine blade ,business.industry ,Mechanical Engineering ,Energy Engineering and Power Technology ,Aerospace Engineering ,Mechanical engineering ,Aerodynamics ,Computational fluid dynamics ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Fuel Technology ,Nuclear Energy and Engineering ,Boss ,law ,0103 physical sciences ,010306 general physics ,business ,Geology - Abstract
Focus of this paper is aerodynamic investigation of tie-boss stabilization devices for extremely long rotor blades. This investigation covered measurements on multiple blade cascades and computational fluid dynamics (CFD) simulation of the flow past these cascades. Conclusions were drawn from results of the measurements and CFD and from the knowledge of prior investigation of the used blade cascade. Main focus of this paper is to describe influence of a tie-boss stabilization device on flow field in interblade channel. Tie-boss with more massive shape proved to cause lesser losses, while tie-boss with a tailored trailing edge showed lesser influence on flow turning.
- Published
- 2018
29. The Sonic Surface in the Inter-Blade Channel of the Last Stage Rotor Wheel in the Steam Turbine of Large Output
- Author
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Martin Luxa
- Subjects
Chord (geometry) ,geography ,geography.geographical_feature_category ,Rotor (electric) ,Acoustics ,Root (chord) ,Inlet ,Span (engineering) ,law.invention ,law ,Steam turbine ,lcsh:TA1-2040 ,Supersonic speed ,lcsh:Engineering (General). Civil engineering (General) ,Communication channel - Abstract
The paper deals with sonic surface in a modern turbine wheel consisting of non-prismatic ultra long blades. The whole inter-blade channel is choked. Different positions and shapes of the sonic line in particular cross-sections along the span are observed. The sensitivity of sonic line formation to small changes of effective shape of the inter-blade channel in the root section and the influence of inlet angle, stagger angle and pitch/chord ratio in the tip section are discussed. The problematic of sonic line development in the case of supersonic inlet flow filed is also described. The presented work is based on results of theoretical, experimental and numerical approaches.
- Published
- 2018
30. Investigation of transonic and supersonic flow in the rotor tip section of the last LP steam turbine stage under different turbulence levels
- Author
-
Petr Louda, Jan Halama, Martin Luxa, Vladimír Hric, Jiri Furst, David Šimurda, Marek Bobcik, Jaroslav Synáč, Jaroslav Fort, and Bartolomej Rudas
- Subjects
Materials science ,Rotor (electric) ,law ,Turbulence ,Nozzle ,Supersonic speed ,Mechanics ,Reynolds-averaged Navier–Stokes equations ,Choked flow ,Transonic ,law.invention ,Wind tunnel - Abstract
Design of a new generation of the large power steam turbines leads to very long last rotor blades with tip sections operating often in supersonic region. The flow field in such tip sections is not fully explored and it is believed to be fairly complex and very sensitive even on minute changes of flow parameters. This stimulated the study of the performance of profiles suitable for rotor tip sections. Numerical simulations have been carried out using TU Prague’s code based on the solution of the RANS equations and SST turbulence model by implicit finite volume method with AUSMPW+ scheme in high resolution formulation. Experimental data have been gathered in the intermittent high-speed wind tunnel of IT CAS CR for 2D cascade measurements equipped by an adjustable supersonic inlet nozzle, perforated inserts at side walls and adjustable perforated tailboard.
- Published
- 2017
31. 3D flow past transonic turbine cascade SE 1050 — Experiment and numerical simulations
- Author
-
David Šimurda, Jiří Fürst, and Martin Luxa
- Subjects
Physics ,Meteorology ,business.industry ,Flow (psychology) ,Experimental data ,Conical surface ,Mechanics ,Computational fluid dynamics ,Condensed Matter Physics ,Kinetic energy ,Vortex ,Cascade ,business ,Transonic - Abstract
This paper is concerned with experimental and numerical research on 3D flow past prismatic turbine cascade SE1050 (known in QNET network as open test case SE1050). The primary goal was to assess the influence of the inlet velocity profile on the flow structures in the interblade channel and on the flow field parameters at the cascade exit and to compare these findings to results of numerical simulations. Investigations of 3D flow past the cascade with non-uniform inlet velocity profile were carried out both experimentally and numerically at subsonic (M2is = 0.8) and at transonic (M2is = 1.2) regime at design angle of incidence. Experimental data was obtained using a traversing device with a five-hole conical probe. Numerically, the 3D flow was simulated by open source code OpenFOAM and in-house code. Analyses of experimental data and CFD simulations have revealed the development of distinctive vortex structures resulting from non-uniform inlet velocity profile. Origin of these structures results in increased loss of kinetic energy and spanwise shift of kinetic energy loss coefficient distribution. Differences found between the subsonic and the transonic case confirm earlier findings available in the literature. Results of CFD and experiments agree reasonably well.
- Published
- 2013
32. Clearance gap flow: extended pneumatic measurements and simulations by discontinuous Galerkin finite element method
- Author
-
Helena Prausová, Jan Vimmr, Martin Luxa, Jindřich Hála, and Ondřej Bublík
- Subjects
Discretization ,Computer science ,Turbulence ,Physics ,QC1-999 ,Static pressure ,Aerodynamics ,Mechanics ,Finite element method ,Physics::Fluid Dynamics ,Discontinuous Galerkin method ,Compressibility ,Range (statistics) ,Statistical physics - Abstract
In the present paper, new results of measurements of the compressible viscous fluid flow in narrow channels with parallel walls under the conditions of aerodynamic choking are presented. Investigation was carried out using the improved test section with enhanced capability to accurately set the parallelism of the channel walls. The measurements were performed for the channels of the dimensions: length 100 mm, width 100 mm and for various heights in the range from 0.5 mm to 4 mm. The results in the form of distribution of the static pressure along the channel axis including the detailed study of the influence of the deviation from parallelism of the channel walls are compared with previous measurements and with numerical simulations performed using an in-house code based on Favre averaged system of Navier-Stokes equations completed with turbulence model of Spalart and Allmaras and a modification of production term according to Langtry and Sjolander. The spatial discretization of the governing equations is performed using the discontinuous Galerkin finite element method which ensures high order spatial accuracy of the numerical solution.
- Published
- 2016
33. SHOCK WAVE BOUNDARY LAYER INTERACTION IN PROFILE CASCADES REPRESENTING ROTOR BLADINGS OF THE LAST STAGE OF LARGE OUTPUT STEAM TURBINES
- Author
-
Jaromir Prihoda, Jana Vachova, Martin Luxa, and David Šimurda
- Subjects
Shock wave ,Engineering ,Boundary layer ,business.industry ,Rotor (electric) ,law ,Steam turbine ,Mechanical engineering ,Stage (hydrology) ,Aerospace engineering ,business ,law.invention - Published
- 2016
34. Mathematical modelling and experimental investigation of gas flow in minichannels and microchannels
- Author
-
Martin Luxa, Rudolf Dvořák, Marek Hajžman, Hynek Klášterka, and Jan Vimmr
- Subjects
Materials science ,Mathematics::Analysis of PDEs ,Laminar flow ,Mechanics ,Solver ,Condensed Matter Physics ,Physics::Fluid Dynamics ,Classical mechanics ,Flow (mathematics) ,Schlieren ,Compressibility ,Boundary value problem ,Gas compressor ,Transonic - Abstract
The first part of this study is focused on the numerical modelling and experimental investigation of transonic flow through a 2D model of the male rotor-housing gap in a dry screw compressor. Numerical simulations of the clearance flow are performed with the help of the in-house compressible Navier-Stokes solver. Experimental measurements based on the Schlieren method in Toepler configuration are carried out. The objective of the second part of the study is to derive the analytical solution of gas microflow development in a gap between two parallel plates. The microflow is assumed to be laminar, incompressible and the velocity slip boundary conditions are considered at the walls. The constant velocity profile is prescribed at the inlet. For the mathematical description of the problem, the Oseen equation is used. The analytical results are compared with the numerical ones obtained using the developed incompressible Navier-Stokes solver including the slip flow boundary conditions.
- Published
- 2010
35. Pneumatic measurements downstream of a radial turbine nozzle cascade
- Author
-
Martin Luxa, David Šimurda, Jan Vimmr, and Rudolf Dvorak
- Subjects
Mechanism (engineering) ,Physics ,Traverse ,Downstream (manufacturing) ,Cascade ,Radial turbine ,Nozzle ,Mechanics ,Conical surface ,Condensed Matter Physics ,Aspect ratio (image) - Abstract
This paper deals mainly with pneumatic measurements on a radial turbine nozzle cascade. The full radial cascade guarantees the exit flow field periodicity downstream of it. A special traversing mechanism with a five — hole conical probe moving along a circular path behind the cascade was used for flow field investigation in this type of cascade with very low aspect ratio. The analyses of results of 2D and 3D pneumatic measurements including loss coefficient values are presented.
- Published
- 2010
36. Clearance gap flow: simulations by discontinuous Galerkin method and experiments
- Author
-
Jindřich Hála, Martin Luxa, Ondřej Bublík, Helena Prausová, and Jan Vimmr
- Subjects
Computer science ,Turbulence ,Physics ,QC1-999 ,Laminar flow ,Mechanics ,Finite element method ,Physics::Fluid Dynamics ,Theoretical physics ,Flow (mathematics) ,Discontinuous Galerkin method ,Compressibility ,Fluid dynamics ,Stagnation pressure - Abstract
Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simu- lation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ − Reθt transition model.
- Published
- 2015
37. Wind Tunnel Measurements of Flow-Induced Vibration of a NACA0015 Airfoil Model
- Author
-
Jan Kozánek, David Šimurda, Martin Luxa, Martin Štěpán, Jaromír Horáček, Petr Šidlof, and Václav Vlček
- Subjects
Physics::Fluid Dynamics ,Vibration ,Airfoil ,Aerodynamic force ,Engineering ,business.industry ,Vortex-induced vibration ,Acoustics ,Flutter ,Dynamic pressure ,business ,Relative wind ,Wind tunnel - Abstract
The paper reports on interferometric measurements of flow over a NACA0015 airfoil model during flutter limit cycle oscillations. The airfoil model is fixed on an elastic support allowing motion with two degrees of freedom — pitch and plunge. The structural mass and stiffness matrices can be tuned to certain extent, so that the eigenfrequencies of the two modes approach as needed. The model is equipped with dynamic pressure probes and sensors measuring the airfoil vertical position. The flow field around the airfoil was measured by Mach-Zehnder interferometer and registered using a high-speed camera synchronously with the mechanical vibration and pressure measurements. The Mach number of the incident airflow was gradually increased and the response of the aeroelastic system to initial impulse measured, until the flutter instability onset occurred. Flutter boundaries were evaluated for various additional masses attached (i.e., for various plunging mode eigenfrequencies), and post-critical behavior of the system investigated. The interferograms recorded by the high-speed camera were postprocessed, yielding pressure distribution around the airfoil during its vibration and an estimate of the total aerodynamic force and energy transfer from the airflow to the structure.Copyright © 2014 by ASME
- Published
- 2014
38. Optimizing the Tip Section Profiles of a Steam Turbine Blading
- Author
-
Rudolf Dvořák, David Šimurda, Pavel Šafařík, and Martin Luxa
- Subjects
Turbine blade ,Steam turbine ,law ,Section (archaeology) ,Mechanical engineering ,Geology ,law.invention - Abstract
Though there is not much freedom in shape modification of profiles for tip sections of steam turbines of large output, there is still enough space for optimizing these profiles. The constraints are already in the thermodynamic design of the last stage blading. The layout of the tip cascade indicates that the optimizing strategy should primarily concern the leading edge region and the trailing edge. Proper design can cut down both the front and exit shock wave intensities and the shock wave direct and indirect losses, as well as attenuate the interacting shock waves. This “partial optimization” method has been experimentally verified and is presented in this paper.
- Published
- 2013
39. Aerodynamic Investigations of Root Sections of Long Rotor Blades Applied at the Last Stages of Steam Turbines
- Author
-
David Šimurda, Pavel Šafařík, Miroslav Šťastný, Martin Luxa, and Jaroslav Synáč
- Subjects
Engineering ,Turbine blade ,business.industry ,Rotor (electric) ,Flow (psychology) ,Structural engineering ,Aerodynamics ,Turbine ,law.invention ,symbols.namesake ,Mach number ,law ,Steam turbine ,symbols ,business ,Transonic - Abstract
The aerodynamics of root sections appears to be a crucial problem in the design and operation of the last stages of large output steam turbines. The reasons are transonic flow, high flow turning, and difficulties with keeping their design aerodynamic conditions during operation. Investigations were performed on planar blade cascades representing root sections of 1085mm and 1220mm long rotor blades. The basic conception of the two root sections differs. The aerodynamic loading of the 1220mm blade root section is lowered in order to ensure that the design parameters are kept during turbine stage operation. We present the results of optical and pneumatic measurements i.e. dependencies of the kinetic energy loss coefficient and exit flow angle on the exit isoentropic Mach number and the angle of incidence, as well as images of the flow fields. The experimental data is analyzed in order to assess and document the difference between the two root section designs.
- Published
- 2012
40. Loss Coefficient Dependence of Turbine Blade Cascade
- Author
-
Milan Mateˇjka, Jaroslav Syna´c´, David Sˇimurda, Martin Luxa, and Pavel Sˇafarˇi´k
- Subjects
Engineering ,Turbine blade ,business.industry ,Rotor (electric) ,Mechanical engineering ,Aerodynamics ,Mechanics ,law.invention ,symbols.namesake ,Mach number ,law ,Steam turbine ,Cascade ,Schlieren ,symbols ,Supersonic speed ,business - Abstract
This paper presents the experimental results of aerodynamic research performed on a blade cascade representing the midsection of 1220 mm long rotor blades of the last stage of a large output steam turbine. The operational regime of the blade cascade is characterized by supersonic exit velocity. Isentropic exit Mach number M2is = 1.323. The experimental data analysis concerns pneumatic measurements to calculate the total pressure and the kinetic energy loss coefficients, and to evaluate them mainly with respect to the aperiodicity of the flow field. The flow structure is also studied on the basis of results obtained by means of optical methods, such as schlieren and interferometric methods.Copyright © 2010 by ASME
- Published
- 2010
41. Aerodynamic Research on the MCA-Type Compressor Blade Cascade
- Author
-
Pavel Sˇafarˇi´k, David Sˇimurda, and Martin Luxa
- Subjects
Engineering ,Boundary layer ,Flow separation ,business.industry ,Cascade ,Structural engineering ,Mechanics ,Aerodynamics ,Subsonic and transonic wind tunnel ,business ,Transonic ,Gas compressor ,Wind tunnel - Abstract
This paper deals with an analysis of the flow through a high cambered compressor blade cascade. The profiles of the blade cascade have been designed to be of MCA-type. The geometric and aerodynamic parameters of the cascade are presented here. The aerodynamic research was performed in a transonic wind tunnel. Optical methods were applied to obtain information on the flow structures taking place in the interblade channels when operating in a range of subsonic and transonic velocities and at various angles of incidence. The internal shock waves and the flow separation in the rear part of the cascade channel were observed and studied. Their influence on the loss coefficient and exit flow angle at subsonic and low transonic region was assessed. The thickness of the sidewall boundary layer in the interblade channel was measured in order to investigate the development of the axial velocity density ratio (AVDR), which plays an important role in the interpretation of the results.Copyright © 2010 by ASME
- Published
- 2010
42. Research on the Tip Sections of a Long Turbine Blade
- Author
-
Martin Luxa, Jaroslav Syna´cˇ, David Sˇimurda, and Pavel Sˇafarˇik
- Subjects
Engineering ,Turbine blade ,business.industry ,Rotor (electric) ,Structural engineering ,Mechanics ,Aerodynamics ,law.invention ,law ,Steam turbine ,Cascade ,Schlieren ,Supersonic speed ,business ,Transonic - Abstract
This paper reports on the results of high-speed aerodynamic research on a blade cascade. The blade cascade represents the tip section of the last stage rotor blades of a large output steam turbine. The aerodynamic characteristics of the blade cascade are presented together with flow field photographs in a range of transonic and supersonic velocities. Pictures of the flow field were obtained by means of interferometry and the schlieren method. The pressure distribution over the profiles was also evaluated using interferometry. Finally, the data for evaluating the losses and other integral characteristics of the flow exiting from the cascade were measured pneumatically with the use of a traversing device. The results are analyzed and discussed.
- Published
- 2008
43. Transonic Flow Past Plane Cascades: Experimental Data Analysis
- Author
-
Pavel Šafařík and Martin Luxa
- Subjects
Shock wave ,Boundary layer ,Plane (geometry) ,Flow (psychology) ,Trailing edge ,Supersonic speed ,Aerodynamics ,Mechanics ,Transonic ,Geology - Abstract
The paper presents results from an aerodynamic investigation of transonic flow past profile cascades. The analysis following the experimental data is aimed at transonic effects namely expansion over sonic conditions, aerodynamic choking, supersonic compression accompanying transonic expansion on the suction side, boundary layer development, the flow past a trailing edge, exit shock waves, interaction of shock wave with boundary layer, wakes, etc.
- Published
- 2003
44. Numerical and experimental investigations of supersonic turbine cascade flow
- Author
-
Synac, J., Rudas, B., Stastny, M., Martin Luxa, Simurda, D., and Safarik, P.
45. AERODYNAMIC DATA FOR TWO VARIANTS OF ROOT TURBINE BLADE SECTIONS FOR A 54' TURBINE ROTOR BLADE
- Author
-
David Šimurda, Martin Luxa, Pavel Šafařík, Bartoloměj Rudas, and Jaroslav Synáč
- Subjects
Pressure drop ,Engineering ,Turbine blade ,business.industry ,Rotor (electric) ,Aerodynamics ,Mechanics ,Structural engineering ,law.invention ,Angle of incidence (aerodynamics) ,symbols.namesake ,Mach number ,law ,Cascade ,symbols ,Limit load ,business - Abstract
Aerodynamic investigations were performed on planar blade cascades representing two alternative root sections of rotor blades 54″ in length with straight fir-tree root. Each of the variants was designed for different number of blades in the rotor. This paper presents the results of measurements showing the dependency of the kinetic energy loss coefficient and the exit flow angle on the exit isoentropic Mach number and the angle of incidence. Images of the flow fields are also presented. The experimental data is analyzed to assess and document the difference between the two root section designs. Results show that requirement of straight fir tree root leading to high design incidence angles significantly limit operation range. Also in case of root sections with high exit Mach numbers a limit load conditions are an issue. In order to utilize available pressure drop blade cascade throat/pitch ratios should be kept as high as possible which favorites variant with lower number of blades and higher outlet metal angle (relative to axial direction).
46. Aerodynamic investigation of the tip section for titanium blade 54'
- Author
-
Martin Luxa, Šimurda, D., Fořt, J., Fürst, J., Šafařík, P., Synáč, J., and Rudas, B.
47. Turbine cascades of last stage blades for wide range of operating conditions
- Author
-
Jan Halama, Marek Bobcik, Jaromir Prihoda, David Šimurda, Zdenek Simka, Jaroslav Fort, Martin Luxa, Jiri Furst, Jaroslav Synáč, Vladimír Hric, Ondrej Novak, and Bartolomej Rudas
- Subjects
Combined cycle ,lcsh:Mechanical engineering and machinery ,Mechanical Engineering ,turbine ,Nozzle ,Energy Engineering and Power Technology ,Aerospace Engineering ,Mechanical engineering ,Turbine ,cascade ,law.invention ,symbols.namesake ,Mach number ,experimental validation ,Cascade ,Steam turbine ,law ,symbols ,Environmental science ,lcsh:TJ1-1570 ,Supersonic speed ,CFD ,last stage blade ,Wind tunnel - Abstract
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 surrounding the steam turbine last stage blades. Therefore, the enlargement of operating range for last stage blades presents new challenges in design of turbine cascades. Several turbine cascades were designed and analyzed by commercial and in-house software of CTU Prague. Selected profiles were experimentally validated in the high-speed wind tunnel for 2D cascade measurements of the Institute of Thermomechanics of the Czech Academy of Sciences which is equipped by an adjustable supersonic inlet nozzle, perforated inserts at side walls and adjustable perforated tailboard. Comparisons are presented of numerical results with optical and pneumatic measurements for a wide range of inlet and outlet Mach numbers for optimized hub and tip profile cascades.
48. Tip cascade aerodynamics of turbine stage blades 48
- Author
-
Synac, J., Rudas, B., Stastny, M., Martin Luxa, Simurda, D., and Safarik, P.
49. CAuses and solution of periodicity of supersonic flow field downstream of a profile cascade
- Author
-
Martin Luxa, Synac, J., Safarik, P., and Simurda, D.
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