Vol. 6, No 4, 2002 < Volumes
(ISSN 1428-6394)

Contents:

  • Ryszard Chodkiewicz, Krzysztof Sobczak, Adam Papierski and Tomasz Borz/ecki CFD Code — a Useful Tool for the Turbomachinery Designer   abstract | full text
  • Andrzej Gardzilewicz, Michał Karcz, Stanisław Marcinkowski, Marcin Bielecki, Janusz Badur, Aleksander Malec and Mariusz Banaszkiewicz Proposal of Modernisation of a Steam Turbine Stage before Extraction, CFD and CSD Analysis   abstract | full text
  • Andrey V. Rusanov, Sergey V. Yershov, Piotr Lampart, Jerzy Świrydczuk and Andrzej Gardzilewicz 3D Multistage Computations of Turbine Flows Using Different State Equations   abstract | full text
  • Maciej Kaniecki Modernization of the Outflow System of Cross-flow Turbines   abstract | full text
  • Frank Kenyery, Robert Rey and Ricardo Noguera Dimensioning and Performance Analysis of an Axial Hydraulic Turbine of High Power//Weight Ratio   abstract | full text
  • Krzysztof Kosowski Application of 3D Flow Solver in Education of Students   abstract | full text
  • Jarosław S. Walijewski and Zenon A. Sosnowski Genetic Tuning Fuzzy Dempster-Shafer Decision Rules   abstract | full text
  • Eugeniusz Zieniuk \nu-Spline Curves for Boundary Geometry Modeling in Two-dimensional Potential Boundary Value Problems with Singular Corner Points   abstract | full text
  • Eugeniusz Zieniuk and Wiesław Gabrel The Identification of the Boundary Geometry with Corner Points in Inverse Two-dimensional Potential Problems   abstract | full text
  • Marian Gryciuk and Jerzy Górecki On Calculations of the Dipole Moment from the Electron Density Data   abstract | full text
  • Maciej Wołoszyn and Andrzej Z. Maksymowicz Coherent Potential Approximation Technique in a Simple Example of Resistivity Calculations for Binary Alloys   abstract | full text

Abstracts:

hRyszard Chodkiewicz, Krzysztof Sobczak, Adam Papierski and Tomasz Borz/ecki CFD Code — a Useful Tool for the Turbomachinery Designer

The presentation of CFX-TASCflow code possibilities for the turbomachinery design is the main aim of this study. In the first part of the work the compressor redesign process is presented. Next, CFX-TASCflow possibilities in predicting unstable operating conditions (surge) are shown. The one-stage, radial blower installed in the Institute of Turbomachinery TU of Lodz has been chosen owing to the available numerous experimental data. The pump calculations discussed in the third part concern a comparison of different turbulence models with the experimental results. In the last part devoted to the turbine redesign, the code usefulness is proved on the examples of the last stage design process.

 

hAndrzej Gardzilewicz, Michał Karcz, Stanisław Marcinkowski, Marcin Bielecki, Janusz Badur, Aleksander Malec and Mariusz Banaszkiewicz Proposal of Modernisation of a Steam Turbine Stage before Extraction, CFD and CSD Analysis

The paper presents an idea and analysis of application of a new solution of a stage before extraction in the modernised LP part of 200MW turbines with ND37 exhaust. The idea of the patent is to introduce to the turbine steam path a ring directing high energy tip leakage steam from the stage to the regenerative extraction. Owing to this it is possible to cheaply achieve some energy benefits from the operation of first heat exchanger which in the modernised 200MW turbine is continuously underheated. Ring design has been checked using CFD and CSD numerical codes.

 

hAndrey V. Rusanov, Sergey V. Yershov, Piotr Lampart, Jerzy Świrydczuk and Andrzej Gardzilewicz 3D Multistage Computations of Turbine Flows Using Different State Equations

The paper describes the implementation of a modified state equation for perfect gas and Tammann equation into a 3D rans solver FlowER. In the modification the specific heats are assumed as linear functions of temperature. A 5-stage LP (low pressure) steam turbine is calculated, and the comparison of results for constant and variable specific heats is illustrated. The modification significantly improves the correctness of determination of thermodynamic parameters in the entire flow region, especially in the exit stage.

 

hMaciej Kaniecki Modernization of the Outflow System of Cross-flow Turbines

The presented article brings general overview of CFD analysis of two cross-flow turbine types (a classical impulse turbine and a reaction turbine). The author focuses his attention mainly on the discussion of differences in flow patterns in the outflow section of these turbines, because this element exerts significant impact on performance properties of the turbine. The article presents a comparison of computations and experimental results of the cross-flow turbine manufactured by IMP PAN. The analysis was performed by means of a computer program Fluent 5.0TM for a twodimensional example.

 

hFrank Kenyery, Robert Rey and Ricardo Noguera Dimensioning and Performance Analysis of an Axial Hydraulic Turbine of High Power//Weight Ratio

The purpose of this research is to develop a methodology for dimensioning and performance analysis of a stage of Hydraulic Axial-Flow Turbines of High Power to Weight Ratio (HAFT-HPWR). The HAFT-HPWR consists of two rows (stator and rotor) with non-twisted blades. The axial flow turbine of higher power to weight ratio is that with a degree of reaction equal to zero. The experimental results on a single stage 50% reaction turbine show a big influence of Reynolds number on the turbine performance. The zone of operation at the best efficiency point varies strongly with the rotation speed. The performance analysis of HAFT-HPWR requires the precise assessment of the influence of the Reynolds number on deflection and the hydraulic losses. Due to complexity of the flow in an axial turbine, such assessment should be based on 3D numerical simulation, in order to compute the hydraulic losses present in a stage of HAFT-HPWR, without using models and correlations.

 

hKrzysztof Kosowski Application of 3D Flow Solver in Education of Students

The development of 3D numerical methods enables the estimation of flow parameters in any section of the channels and in this way the complex phenomenon of generation of losses can be investigated. Application of 3D solver helps in better understanding of flow behaviour in turbine stages, while basing on the results of calculations of stages of different geometries, it is possible to show the effect of different design parameters on the turbine stage output and its efficiency. The paper presents the examples of application of modern computer programs for teaching turbomachinery problems, for research flows in turbine stages and for solving design tasks. Some examples of students' projects are also included.

 

hJarosław S. Walijewski and Zenon A. Sosnowski Genetic Tuning Fuzzy Dempster-Shafer Decision Rules

The objective of this paper is to employ the Dempster-Shafer theory (DST) as a vehicle supporting the generation of fuzzy decision rules. The concept of fuzzy granulation realized via fuzzy clustering is aimed at the discretization of continuous attributes. Next we use Genetic for tuning fuzzy decision rules. Detailed experimental studies are presented concerning well-known medical data sets available on the Web.

 

hEugeniusz Zieniuk \nu-Spline Curves for Boundary Geometry Modeling in Two-dimensional Potential Boundary Value Problems with Singular Corner Points

The paper presents a new modeling method of boundary geometry in boundary valueproblems by ν-spline curves. To define a smooth boundary geometry both Bézier and B-spline curves are applied. At the segment join points Bézier curves ensure continuity C 1 , and B-spline curves allow us to maintain C 2 continuity. However, the curves hinder boundary modeling with corner points. In order to weaken the continuity at segment join points ν-spline curves are proposed. These curves are combined analytically with the Green formula, thus yielding the Parametric Integral Equation System (PIES). To solve the PIES a pseudospectral method is used. The results obtained for the domains with singular corner points are compared with the corresponding non-singular ones as defined by the ν-spline curves.

 

hEugeniusz Zieniuk and Wiesław Gabrel The Identification of the Boundary Geometry with Corner Points in Inverse Two-dimensional Potential Problems

The paper presents fragment of a larger study concerning the effective methods of solving the inverse boundary value problems. The boundary value problem described here is formulated as a problem of the identification of a boundary geometry with corner points. A method using a parametric integral equations system (PIES) is proposed. PIES used in the method makes the easy modelling of the geometry with corner points possible. This effect is obtained by the application of modified splines. An evolution algorithm is used for the effective control of modifications of the boundary geometry. Some experimental tests of the efficiency of the discussed method were performed for two-dimensional inverse potential problems.

 

hMarian Gryciuk and Jerzy Górecki On Calculations of the Dipole Moment from the Electron Density Data

In the paper we discuss how to calculate the dipole moment using the electron density data. A few numerical methods are compared. We have found that usually the interpolation of electron density gives the most accurate results.

 

hMaciej Wołoszyn and Andrzej Z. Maksymowicz Coherent Potential Approximation Technique in a Simple Example of Resistivity Calculations for Binary Alloys

Technique of the Coherent Potential Approximation applied for calculations of the density of states in binary alloys Ax B1−x is presented. Results of the calculations are also used to find the residual resistivity of the system versus concentration x.

 

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