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1
Content available Experimental and numerical validation of the improved vortex method applied to CP745 marine propeller model
Król P., Tesch K.
Polish Maritime Research
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2018
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nr 2
57--65
EN
The article presents a numerical analysis of the CP745 marine propeller model by means of the improved vortex method and CFD simulations. Both numerical approaches are validated experimentally by comparing with open water characteristics of the propeller. The introduced modification of the vortex method couples the lifting surface approach for the propeller blades and the boundary element method for the hub. What is more, a simple algorithm for determination of the propeller induced advance angles is established. The proposed modifications provide better results than the original version of the vortex method. The accuracy of the improved method becomes comparable to CFD predictions, being at the same time a few hundred times faster than CFD.
2
Content available Minimum drag shape bodies moving in inviscid fluid – revisite
Tesch K., Kaczorowska K.
Transactions of the Institute of Fluid-Flow Machinery
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2017
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nr 135
73--85
EN
This paper presents the classic approach to minimum drag shape body problem, moving at hypersonic speeds, leading to famous power law shapes with value of the exponent of 3 4. Twoand three-dimensional cases are considered. Furthermore, an exact pseudo solution is given and its uselessness is discussed. Two new solutions are introduced, namely an approximate solution due to form of the functional and solution by means of optimisation of a Bézier curve. The former transforms the variational problem to the classic problem of function optimisation by assuming certain class of functions, whereas the latter by means of discretised functional.
3
Content available A short review of blood flow modelling methods: from macro- to microscales
Kaczorowska K., Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2017
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Vol. 21, No 1
5--16
EN
The aim of this paper it to review various scale approaches to the blood flow modelling. Blood motion may be described by three types of mathematical models according to the observed scales or resolutions, namely microscopic, mesoscopic and macroscopic descriptions. The above approaches are discussed together with their advantages and disadvantages. Several results of mesoscopic simulations are presented with particular attention paid to mesoscale semi-continuum models suitable for real-time blood flow visualisation.
4
Content available remote On invariants of fluid mechanics tensors
Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2013
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Vol. 17, No 3-4
223--230
EN
This paper presents physical interpretations of the first and second invariants of tensors of fluid mechanics. Some examples of elementary applications and meanings are also given.
5
Content available remote Generalised Herschel model applied to blood flow modelling
Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2012
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Vol. 16, No 3-4
253--262
EN
This paper introduces a new rheological model of blood as a certain generalization of the standard Herschel-Bulkley model (Herschel W H and Bulkley R 1926 Kolloid-Zeitschnft 39 (4) 291). This model is a rheological constitutive equation and belongs to the group of the so-called generalised Newtonian fluids. Experimental data (Yeleswarapu K K et al. 1998 Mech. Res. Comm. 25 (3) 257) is compared with the results obtained from the new model, to demonstrate that it allows obtaining the best agreement together with the Luo-Kuang model (Luo X and Kuang Z B 1992 J. Biomechanics 25 (8) 929; Easthope P L and Brooks D E 1980 Biorheology 17 235). The new model may be easily implemented into commercial CFD codes, which is not that obvious for more complicated models such as differential, integral and rate type fluids (Astarita G and Marrucci G 1974 Principles of non-Newtonian Fluid Mechanics London, McGraw-Hill; Tesch K 2012 Selected Topics of Blood Flows and Microclimate Modelling in Protective Suits Gdansk. Gdansk University of Technology Press). What is more, it allows modelling of such phenomena as shear thinning, yield stress and constant viscosity values at high shear rates.
6
Content available Numerical prediction of steady and unsteady tip vortex cavitation on hydrofoils
Flaszyński P., Szantyr J. A., Tesch K.
Polish Maritime Research
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2012
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nr 3
3-15
EN
The article presents the numerical method for prediction of tip vortex cavitation generated on hydrofoils. This method has been developed in the course of numerical and experimental research described in earlier publications. The objective of the research was to design the optimum discrete grid structure for this specific computational task and to select the best turbulence model for such an application The article includes a short description of the method and a computational example demonstrating its performance. In this example the results of numerical prediction of the cavitating tip vortex obtained from two commercial CFD codes are compared with experimental photographs taken in the cavitation tunnel in the corresponding flow conditions. Altogether nine different flow conditions are tested and analyzed, but only selected results are included. The accuracy of the numerical predictions is discussed and the reasons for minor existing discrepancies are identified. The unsteady tip vortex calculations are also presented, showing the fluctuations of the transverse velocity components predicted for three cross-sections of the cavitating vortex kernel.
7
Content available remote On a method of efficiency increasing in Kaplan turbine
Banaszek M., Tesch K.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2011
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nr 140
29-38
EN
This paper presents a method of increasing efficiency in Kaplan-type turbine. The method is based on blade profile optimisation together with modeling the interaction between rotor and stator blades. Loss coefficient was chosen as the optimisation criterion, which is related directly to efficiency. Global optimum was found by means of Genetic Algorithms, and Artificial Neural Networks were utilized for approximations to reduce long calculation time.
8
Content available remote Variational Method of Finding Streamlines in Ring Cascades for Creeping Flows
Tesch K., Banaszek M.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2011
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Vol. 15, No 1
71-84
EN
This paper presents a new analytical method of finding streamlines for creeping flows in a ring cascade composed of an infinite number of infinitely thin blades. An analytical solution was obtained by minimizing the dissipation functional by means of the variational calculus. The necessary condition for the optimum of the functional yields the Stokes equation after certain additional assumptions are introduced. We considered different variants of fixing of the inlet and outlet of the cascade.
9
Content available remote Experimental validation of numerical model within a flow configuration of the model Kaplan turbine
Krzemianowski Z., Banaszek M., Tesch K.
Mechanics and Mechanical Engineering
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2011
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Vol. 15, nr 3
297-307
EN
This paper investigates validations of flow within a model Kaplan turbine. This includes comparison of various turbulence models and their influence on torque and power generated by the turbine. Numerical were compared with experimental data.
10
Content available remote Rotor Blade Geometry Optimization in Kaplan Turbine
Banaszek M., Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2010
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Vol. 14, No 3
209-225
EN
This paper presents a description of the method and results of rotor blade shape optimization. The rotor blading constitutes a part of a turbine’s flow path. The optimization consists in selecting a shape that minimizes the polytrophic loss ratio [1]. The shape of the blade is defined by the mean camber line and thickness of the airfoil. The thickness is distributed around the camber line based on the ratio of distribution. A global optimization was done by means of Genetic Algorithms (GA) with the help of Artificial Neural Networks (ANN) for approximations. For the numerical simulation of a flow through the model Kaplan turbine, the geometry employed in the model was based on the actual geometry of the existing test stage. The fluid parameters and the boundary conditions for the model were based on experimental measurements which were carried out at the test stand at the Department of Turbomachinery and Fluid Mechanics at the Gdansk University of Technology. The shape of the blading was optimized for the operational point with a maximum efficiency.
11
Content available remote On Some Extensions of Murray's Law
Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2010
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Vol. 14, No 3
227-235
EN
This paper cites the original Murray’s law about optimal radii. Extensions to some class of non-Newtonian flows that are described by the Ostwald-de Waele model and the Newtonian flows for elliptical cross-sections. A generalisation of Murray’s law for multi-objective formulation is also given. It is shown that the original formulation of the optimal condition is a particular case of the multi-objective formulation.
12
Content available remote 1D Model Calibration Based on 3D Calculations for Tesla Turbine
Puzyrewski R., Tesch K.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2010
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Vol. 14, No 3
237-248
EN
This paper presents a system of equations for an axisymmetric laminar flow, after averaging, through the width of the interdisk slit of a Tesla turbine. Coefficients improving the efficiency of a 1D model were introduced as a result of averaging. The minimal number of such coefficients was determined. The 1D model makes it possible to attain analytical solutions to an accuracy limited by these coefficients. The calibration of a 1D model depends on finding the numerical values of coefficients that yield a sufficient accuracy compared with 3D calculations. A definition of the efficiency coefficient for the Tesla turbine is also given. This definition relies on the 1D model results. Example values of this coefficient are described after the 1D model calibration.
13
Określenie intensywności procesu dyssypacyjnego w przepływie pełzającym przez wybrane palisady łopatkowe
Tesch K.
Zeszyty Naukowe Instytutu Maszyn Przepływowych Polskiej Akademii Nauk w Gdańsku
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2000
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nr 516/1475
1--15
14
Content available remote Optymalizowanie kształtu kanału palisadowego w ramach przepływów pełzających
Tesch K.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2000
|
nr 117, vol. 1
273-278
PL
W referacie pokazano sposób znajdowania optymalnego kształtu kanału palisadowego przy przepływach pełzających czynnika nieściśliwego. Optymalność rozumiana jest przez minimalizowanie mocy dyssypowanej energii.
EN
The paper presents a method for optimizing the shapes of a cascade flow channel under creeping flow conditions of an incompressible medium. Optimization is here understood in the sense of minimizing the dissipated power.
15
Content available remote Sweep, lean, taper and twist of nozzle blading in 2D model. Inverse problem.
Puzyrewski R., Tesch K.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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1999
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nr 115
327--336
EN
The paper objectives is to show how different factors named here as sweep, lean, taper and twist appears in the solution of the inverse problem within the frame of 2D model. The skeletons of the channels or profiles are the results of the solution of the in verse problem. They can be converted into the shapes of blading.
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