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Solution of parameters of compressible viscous fluid flow through a minichannel
Hála, Jindřich ; Šafařík, Pavel ; Luxa, Martin
In this paper the results of the experiment of the choked air flow through channel with characteristic dimensions: height 2mm, width 100mm, length 100mm will be presented. On the bases of the both pneumatic and optical measurements the development of the flow properties along the channel and the influence of the dissipative processes will be described. The results of the experiment will be compared to the theoretical results and to the results of the numerical simulation. At the end the comparison will be thoroughly discussed.
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Notes to Aerodynamic Testing of Supersonic Blade Cascades
Šimurda, David ; Luxa, Martin ; Šafařík, Pavel
Relatively narrow space for aerodynamic design of long rotor blades applied at last stages of large output steam turbines often results in blades with tips operating at supersonic regimes. This brings number of problems. Main of these are additional sources of loss and rather thin border between sections operating under turbine and compressor regimes one adding to performance and the other deteriorating it. Therefore, aerodynamic cascade data on turbine blading for a range of supersonic inlet and outlet conditions are needed. However, ensuring specified supersonic conditions in a high-speed wind tunnel for blade cascade tests is not an easy task and thus it deserves attention.
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Oblique Shock Wawes in Saturated Steam
Šimurda, David ; Nový, A. ; Šafařík, Pavel
The paper deals with modeling of oblique shock waves in saturated steam. A theoretical model is based on balance of mass, momentum and energy taking in account shock wave geometry. Numerical solution of steam parameters is performed using the IAPWS-IF97 steam thermodynamic properties. The aerodynamic calculation problem is formulated to solve oblique shock wave parameters for saturated steam upstream of the oblique shock. Achieved results are presented by means of hodograph shock polars and pressure-deflection shock polars and they are analyzed and discussed.
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Modelling Flow Processes in Turbomachines using Wind Tunnels
Šafařík, Pavel ; Luxa, Martin ; Šimurda, David
The contribution is concerned with process of preparing and executing high speed aerodynamic research on models of turbomachinery flow parts. Results of research on flow past blade cascades representing sections of turbomachinery bladings are discussed. Employed optical methods of measurement provide basis for descriptions of high speed flow field structures and also for quantification of flowfield parameters. Traversing with five hole conical probe in exit flow field provide aerodynamic parameters important for design and further development of turbomachinery. Presented results have been selected from large database containing data on modelling flow parts of large output steam turbine last stages, radial compressor inducer and research on flow past compressor cascade. Results of research on flow past turbomachinery flow parts at off design conditions of operation are also presented and discussed.
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On Parameters of Shock Waves in Saturated Steam
Nový, A. ; Jícha, D. ; Šafařík, Pavel ; Hajšman, M.
The paper deals with theoretical and numerical study of shock wave parameters in saturated steam. Theoretical approach is based on mass, momentum and energy balance equations. An iterative procedure for solution of state parameters is derived. Numerical solution of steam parameters is performed by means of the iterative procedure using the IAPWS-IF97 water and steam thermodynamic properties. Results are presented and compared with results obtained from ideal gas theory.
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Aerodynamics tests of a transonic turbine blade cascade model consisting of low number of blades
Šimurda, David ; Luxa, Martin ; Šafařík, Pavel ; Synáč, J.
Contribution is concerned with experimental investigation of the transonic turbine blade cascade aerodynamic characteristics. Due to specific geometry of the blade cascade, the blade cascade model consists of six blades only. Therefore, special experimental setup is adopted and its influence on the resultant blade cascade aerodynamic characteristics is discussed. Experimental data are obtained applying both optical (interferometry, schlieren technique) and pneumatic methods (mainly traversing with a five-hole conical probe). Special attention is paid to flow structures, which significantly contribute to the increase of kinetic energy loss coefficient. Results of current investigation are compared to former results obtained at usual experimental set-up.
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Annular Jets and Annular Impinging Jets
Turek, Tomáš ; Trávníček, Zdeněk ; Šafařík, Pavel ; Tesař, Václav
A near field of annular jets and annular impinging jets is experimentally investigated at three inner/outer diameter ratios 0.84, 0.90 and 0.95. Time-mean velocity profiles are evaluated, and three main flow field zones are distinguished – in agreement with the literature, namely the initial merging zone, the intermediate one, and the fully merged one. A distribution of the pressure on the impingement wall is measured for various nozzle-to-wall distances. Two basic annular impinging jet regimes are clearly distinguished, with either small or large recirculation bubbles. Moreover, a hysteretic behavior has been identified under specific parameters.
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