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Mathematical Modelling and Experimental Investigation of Gas Flow in Minichannels and Microchannels

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Journal of Thermal Science 2010年第4期19卷 289-294页

作者： Jan Vimmr Hynek Klterka Marek Hajzman martin luxa Rudolf Dvork University of West Bohemia Faculty of Applied SciencesDepartment of MechanicsUniverzitni 22CZ-306 14 Pilsen Czech Republic University of West Bohemia Faculty of Mechanical EngineeringDepartment of Power System EngineeringUniverzitni 22CZ-306 14 PilsenCzech Republic Institute of Thermomechanics of Academy of Sciences of the Czech Republic Department of Fluid Dynamics Dolejskova 5CZ-182 00 PragueCzech Republic

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 *** simulations of the clearance flow are performed with the help of the in-house compressible Navier-Stokes *** measurements based on the Schlieren method in Toepler configuration are carried *** objective of the second part of the study is to derive the analytical solution of gas microflow development in a gap between two parallel *** microflow is assumed to be laminar,incompressible and the velocity slip boundary conditions are considered at the *** constant velocity profile is prescribed at the *** the mathematical description of the problem,the Oseen equation is *** analytical results are compared with the numerical ones obtained using the developed incompressible Navier-Stokes solver including the slip flow boundary conditions.

关键词： clearance gap transonic flow compressible Navier-Stokes solver mieroflow development Oseen flow model analytical solution incompressible Navier-Stokes solver

Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade

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Journal of Thermal Science 2018年第2期27卷 95-102页

作者： Jindrich Hala martin luxa David Simurda marek Bobcik Ondrej Novak Bartolomej Rudas Jaroslav Synac Institute of Thermomechanics of The Czech Academy of Sciences Prague Czech Republic Doosan Skoda Power Ltd Pilsen Czech Republic Faculty of Mechanical Engineering University of West Bohemia Pilsen Czech Republic

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 Math 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）.

关键词： steam turbine blade cascade root section

Near-Wall Flow in the Blade Cascades Representing Last Rotor Root Sections of Large Output Steam Turbines

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Journal of Thermal Science 2021年第1期30卷 220-230页

作者： ŠIMURDA David FÜRST Jiří HÁLA Jindřich luxa martin BOBČÍK Marek NOVÁK Ondřej SYNÁČJaroslav Institute of Thermomechanics of the Czech Academy of Sciences Prague 18200Czech Republic Dpt.of Technical Mathematics Faculty of Mechanical EngineeringCTU in PraguePrague 12000Czech Republic Doosan Skoda Power Pilsen 30100Czech Republic

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 *** were drawn based on RANS numerical simulations of both variants and on the experimental data obtained by the 3 D traversing in the exit flow field of one of the *** of 3 D structures at two different regimes and its influence on aerodynamic characteristics of the blade cascades was *** distributions of Mach number along the profiles were compared with 2 D optical measurements and its distortion due to the presence of the sidewall was *** interaction between main vortical structures was described and its influence on the loading of the blades,mechanical energy losses and exit flow angle was *** results showed that for a front loaded blade the vortical structures appeared earlier and at a larger extent than for an aft loaded ***,due to different Mach number distribution,contribution of end wall flow to the energy losses was lower in the case of the aft loaded *** 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.

关键词： turbine blade cascade secondary flow near wall flow supersonic flow CFD experiment

Investigation of the Compressible Flow through the Tip-Section Turbine Blade Cascade with Supersonic Inlet

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Journal of Thermal Science 2016年第2期25卷 138-144页

作者： martin luxa Jaromír Príhoda David Simurda Petr Straka Jaroslav Synác Institute of Thermomechanics AS CR v.v.i. Dolejskova 1402/5 18200 Prague Czech Republic Aerospace Research and Test Establishment Plc Beranovych 130 19905 Prague Czech Republic Doosan Skoda Power Co. Ltd. Tylova 1/57 30128 Pilsen Czech Republic

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. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and P?íhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.

关键词： long turbine rotor blade supersonic tip section optical methods transition modelling CFD