Wyniki wyszukiwania - BazTech

1

Experimental research and CFD calculations based investigations into gas flow in a short segment of a heavily worn straight through labyrinth seal

Joachimiak D., Krzyślak P.

Polish Maritime Research

|

2017

|

nr 2

83--88

EN

Steam turbines are used as propulsion components in not only power plants but also on merchant and naval ships. The geometry of the steam turbine seals changes throughout the machine life cycle. The rate of deterioration of these seals, in turn, affects heavily the efficiency of the thermal machine. However, the literature overview does not provide any research reports on flow phenomena occurring in heavily deteriorated seals. The paper describes the course and results of investigations into a model straight through labyrinth seal composed of 4 discs, each with the slot height of 2 mm. The investigations have been conducted with air as the working medium. Changes of gas flow parameters due to wear were analysed. Based on the experimental data, more intensive leakage was observed as the result of the increased slot height. The static pressure distribution along the examined segment was measured. The experimentally recorded distribution differed remarkably from the theoretical assumptions. Another part of the experimental research focused on comparing the gas velocities at points situated upstream of the first and second seal disc. The velocity measurements were carried out using a constant temperature wire probe. This part of the investigations provided opportunities for analysing the influence of seal wear on gas flow conditions in the seal segment. The paper compares the results of the experimental research with those obtained using the CFX software. The presented results of velocity distributions provide a clear picture of the nature of the gas flow in the seal, which enables its analysis.

2

Method of modeling gas turbine performance

Wasik P., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2017

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Vol. 69, No. 1

61--79

EN

The basis of a combined cycle gas turbine mass and energy balance, carried at the concept stage, preliminary design or during analysis, is the calculation of the gas turbine design point. This article presents a gas turbine unit mathematical modelling process intended for implementation of the model in a computer program. The aim of the development was a relatively simple, practical from engineer’s point of view, and universal gas turbine model with a classic, open system design: compressor – combustion chamber – turbine. Attempts have been made to maintain the accuracy of modelling and to keep the ability for extension of the model so to be able to simulate the operation of the turbine at off-design conditions, in particular at part load. Stationary operation of the unit at nominal load is assumed. Thermodynamic system modelling methods, on the level of its global structure, have been submitted. Problems related to the aforementioned issues are discussed and ways to resolve them proposed. The developed model has been implemented in a dynamic link library written in C++ language with usage of C/C++ Minpack numerical library [Keating 2007, Razak 2007].

PL

Zwiększający się w światowym bilansie produkcji energii elektrycznej udział energii wytwarzanej z gazu ziemnego warunkuje tempo przyrostu ilości elektrowni i elektrociepłowni gazowo parowych. Pomimo wysokich cen gazu ziemnego, bloki gazowo parowe są atrakcyjne dla inwestorów z uwagi na: najwyższą sprawność wśród stosowanych na szeroką skalę instalacji energetycznych zasilanych paliwami kopalnymi, dopracowaną technologię skutkującą wysoką niezawodnością, wysoką elastyczność eksploatacyjną, słabe oddziaływanie na środowisko (niskie emisje dzięki wysokiej sprawności i opalaniu gazem ziemnym). Podstawą obliczeń układu kombinowanego na etapie koncepcjonowania/projektowania wstępnego lub podczas jego analizowania są obliczenia turbozespołu gazowego pracującego w punkcie konstrukcyjnym. W artykule przedstawiono krok po kroku proces modelowania matematycznego zespołu turbiny gazowej pod kątem implementacji modelu w programie obliczeniowym. Założono stacjonarną pracę układu przy pełnym obciążeniu. Przewidywanym zastosowaniem modelu jest przede wszystkim symulacja turbiny gazowej skojarzonej z parowym kotłem odzyskowym, tym samym działającej w kombibloku. Omówiono problemy związane z poruszanym zagadnieniem oraz zaproponowano sposoby ich rozwiązania.

3

Description of a test stand and measurement equipment for labyrinth seal testing

Joachimiak D., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2017

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Vol. 69, No. 3

21--35

EN

The paper presents a test stand for testing segments of single sided and double-sided labyrinth seals. The geometry of the test stand has been designed and constructed by the authors of the paper. The elements and the design of the test stand allow investigations of the seal for a variety of initial pressures with the measurement of the mass flow in the inlet and outlet channels. The design of the test stand enables testing seal segments with a turbulent flow. The geometry of the mating pairs of single and double-sided seals allows a measurement of the pressure in selected chambers of the seal chambers.

PL

W artykule przedstawiono stanowisko do badań segmentów uszczelnień labiryntowych jednostronnych i dwustronnych. Geometria stanowiska została zaprojektowana i wykonana przez autorów. Elementy i konstrukcja stanowiska umożliwiają przeprowadzenie badań uszczelnienia z uwzględnieniem różnych zakresów ciśnienia początkowego z pomiarem strumienia masy w kanale dopływowym i kanałach wypływowych. Konstrukcja stanowiska umożliwia badanie segmentów uszczelnień z zaburzonym przepływem. Geometria korpusu i wsadu uszczelnień jednostronnego i dwustronnego umożliwia pomiar ciśnienia w wybranych komorach uszczelnienia.

4

Analysis of heat flow in a tube bank of a condenser considering the influence of air

Joachimiak M., Joachimiak D., Krzyślak P.

Archives of Thermodynamics

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2017

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Vol. 38, no. 3

119--134

EN

The pressure of wet water vapor inside a condenser has a great impact on the efficiency of thermal cycle. The value of this pressure depends on the mass share of inert gases (air). The knowledge of the spots where the air accumulates allows its effective extraction from the condenser, thus improving the conditions of condensation. The condensation of water vapor with the share of inert gas in a model tube bank of a condenser has been analyzed in this paper. The models include a static pressure loss of the water vapor/air mixture and the resultant changes in the water vapor parameters. The mass share of air in water vapor was calculated using the Dalton’s law. The model includes changes of flow and thermodynamic parameters based on the partial pressure of water vapor utilizing programmed water vapor tables. In the description of the conditions of condensation the Nusselts theory was applied. The model allows for a deterioration of the heat flow conditions resulting from the presence of air. The paper contains calculations of the water vapor flow with the initial mass share of air in the range 0.2 to 1%. The results of calculations clearly show a great impact of the share of air on the flow conditions and the deterioration of the conditions of condensation. The data obtained through the model for a given air/water vapor mixture velocity upstream of the tube bank allow for identification of the spots where the air accumulates.

5

A model of gas flow with friction in a slotted seal

Joachimiak D., Krzyślak P.

Archives of Thermodynamics

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2016

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Vol. 37, no. 3

95--108

EN

The paper discusses thermodynamic phenomena accompanying the flow of gas in a slotted seal. The analysis of the gas flow has been described based on an irreversible adiabatic transformation. A model based on the equation of total enthalpy balance has been proposed. The iterative process of the model aims at obtaining such a gas temperature distribution that will fulfill the continuity equation. The model allows for dissipation of the kinetic energy into friction heat by making use of the Blasius equation to determine the friction coefficient. Within the works, experimental research has been performed of the gas flow in a slotted seal of slot height 2 mm. Based on the experimental data, the equation of local friction coefficient was modified with a correction parameter. This parameter was described with the function of pressure ratio to obtain a mass flow of the value from the experiment. The reason for taking up of this problem is the absence of high accuracy models for calculating the gas flow in slotted seals. The proposed model allows an accurate determination of the mass flow in a slotted seal based on the geometry and gas initial and final parameters.

6

Comparison of results of experimental research with numerical calculations of a model one-sided seal

Joachimiak D., Krzyślak P.

Archives of Thermodynamics

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2015

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Vol. 36, no. 2

61--74

EN

Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.

7

Analiza rozkładu prędkości w komorze uszczelnienia labiryntowego na podstawie badań eksperymentalnych i obliczeń numerycznych

Joachimiak D., Krzyślak P.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2014

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z. 86 [290], nr 2

215--224

PL

W pracy przedstawiono wyniki badań eksperymentalnych i numerycznych badania rozkładu prędkości w dziesiątej komorze modelowego segmentu uszczelnienia labiryntowego składającego się z dwudziestu tarcz. Pomiar ciśnienia dynamicznego wykonano sondą Pito i sondą ciśnienia statycznego. Badania eksperymentalne przeprowadzono w trzech płaszczyznach komory. W obliczeniach numerycznych założono warunki termodynamiczne i przepływowe występujące w warunkach pomiaru. Praca zawiera porównanie prędkości osiowych powietrza w wymienionych płaszczyznach uzyskanych z eksperymentu i obliczeń.

EN

The paper presents the results of the experimental and numerical studies of the velocity distribution in the tenth chamber of labyrinth seal of model segment consisting of twenty discs. The measurement of the dynamic pressure was carried out by using both Pito and static pressure probes. Experimental tests were carried out at three planes of the chamber. In numerical calculations thermodynamic and flow conditions occurring during the measurement were assumed. The work includes a comparison between the experimental and calculated values of axial air velocities at above mentioned planes.

8

The analyzis of the stream-air mixture during a flow through a tube bank inside a condenser

Krzyślak P., Joachimiak M.

Transactions of the Institute of Fluid-Flow Machinery

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2014

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nr 126

131--140

EN

The paper presents the results of calculations related to the flow analysis of a tube bank taking into account the partial pressures of gases flowing through the condenser. Different mass share of the gas not condensing in the heat exchanger upstream to the first row of tubes and the partial pressures of water vapor and air have been taken into account. The value of the partial pressures of gases, pressures drop, temperature, velocity, Reynolds number, and air share in the subsequent rows of tubes have been calculated. This study is a basis for the analysis of heat exchange in the condenser considering the influence of the noncondensing gas. The increase in the share of air in the following rows of tubes results in an increase in the thermal resistance and condensation of increasingly lower mass of water vapor.

9

The theory of graphs as a potential tool for modeling of combined heat and power plant network elements

Semkło Ł., Ciałkowski M., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2014

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Vol. 66, No. 4

57--70

EN

The following article provides a brief introduction to the graph theory. It shows two types of models which have been developed using the graph theory. Additionally presented are conservation equations of mass, momentum and energy. The article covers the three elements of the network such as the they are straight pipe and change of the flow direction and a circular arc. These elements are described by the rules of behavior. Identified and described the patterns of loss coefficients.

PL

Artykuł stanowi krótkie wprowadzenie do teorii grafów. Przedstawiono w nim dwa rodzaje modeli utworzonych za pomocą teorii grafów. Dodatkowo opisano zasady zachowania masy, pędu i energii. Uwzględniono podstawowe elementy sieci, takie jak rura prosta oraz łuk kołowy i zmiana kierunku przepływu. Elementy te opisano za pomocą zasad zachowania masy, pędu i energii. Określono i opisano wzory na współczynniki strat.

10

Calculations of labyrinth seals with and without diagnostic extraction in fluid-flow machines

Kaszowski P., Dzida M., Krzyślak P.

Polish Maritime Research

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2013

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nr 4

34--38

EN

Labyrinth seals are essential components of steam turbine unit constructions. Two types of labyrinth seals can be named, the first of which is the seal without diagnostic steam extraction, and the second – with extraction. The distribution of flow parameters along the packing is affected remarkably by the average seal clearance. The presence of diagnostic extraction leads to the equation system which is determinable and can be inversed to calculate the average seal clearance Si. Analysing the obtained results leads to the conclusion that the information about this parameter provides opportunities to monitor the current state of the packing in real time. The applied calculation procedure bases on the de Saint - Venant equation. The article also includes a brief description of both types of seals.

11

The analysis of the changes in the partial pressure of gases and the share of air during a flow through a tube bank inside a condenser

Joachimiak M., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2013

|

Vol. 65, No. 4

13--21

EN

The paper presents the results of calculations related to the flow analysis of gases in a model tube bank of a condenser. Different mass share of the gas not condensing in the heat exchanger upstream of the first row of tubes and the partial pressures of water vapor and air have been taken into account. The value of the partial pressures of gases, pressure drop, temperature, velocity, Reynolds number, and air share in the subsequent rows of tubes have been calculated. This study is a basis for the analysis of heat exchange in the condenser considering the influence of the non-condensing gas.

PL

W pracy przedstawiono wyniki obliczeń dotyczących analizy przepływowej gazów w modelowym pęczku rurowym skraplacza. Uwzględniono różny udział masowy gazu nieskraplającego się w wymienniku ciepła przed pierwszym rzędem rur oraz ciśnienia składnikowe pary wodnej i powietrza. Obliczono wartości ciśnień składnikowych obu gazów, spadku ciśnienia, temperatury, prędkości, liczby Reynoldsa, udziału powietrza w kolejnych rzędach rur. Praca ta stanowi podstawę do analizy wymiany ciepła w skraplaczu z uwzględnieniem wpływu gazu nieskraplającego się.

12

Opis programu Dławnica służącego do obliczeń uszczelnień labiryntowych

Joachimiak D., Joachimiak M., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2013

|

Vol. 65, No. 1

25--35

PL

W artykule przedstawiono algorytm programu DŁAWNICA, który służy do obliczeń uszczelnień labiryntowych. W programie przepływ jednowymiarowy gazu przez kryzę opisano za pomocą parabolicznego równania de Saint-Venanta-Wanzela. W kodzie programu, napisanym w języku Fortran 90, założono przepływ izentalpowy i stałe ciepło właściwe gazu. Pominięto wymianę ciepła pomiędzy gazem a ściankami uszczelnienia. DŁAWNICA umożliwia obliczanie uszczelnień o dowolnej liczbie kryz i dowolnej stałej geometrii, którą określa się współczynnikiem kontrakcji przepływu μ. Program pozwala na wykonywanie obliczeń dławnic z upustem czynnika roboczego, którego posadowienie i wielkość są definiowane. W celu uniknięcia błędów numerycznych w trakcie obliczeń iteracyjnych algorytm sprawdza osobliwość głównej macierzy.

EN

The program builds on the linearized system of n equations based on a formula deSaint-Venant-Wanzel. Iteration operations performed on the matrix equations allow theapproximation to the desired pressure distribution in the spaces between the flanges. On the basis of the calculated pressure distribution determined mass flow flowing through the seal. With the decomposition of the matrix C on triangular matrices L and U significantly minimized the number of algebraic operations necessary to obtain the result. This effect is achieved by skipping the algebraic operations on zero elements, whose number was considerable. The program performs calculations iterations until the assumed accuracy of calculations ε. The design program allows its extension to calculate the additional parameters of gas in the gland which can be: speed and gas flow Mach number. Although minimizing the number of operations and to achieve significant computational accuracy of the sensitivity matrix C should be identified by calculating the parameter cond (C), which is a measure of relative error.

13

Określenie minimalnego poziomu paliwa w zasobniku przykotłowym

Kłosowiak R., Krzyślak P., Bartoszewicz J.

Journal of Mechanical and Transport Engineering

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2013

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Vol. 65, No. 2

17--26

PL

W artykule przedstawiono wyniki badań eksperymentalnych mających na celu określe¬nie minimalnego poziomu paliwa w zasobniku, od czego zależy ilość pyłów wydostających się ponad paliwo w trakcie przejścia fali ciśnieniowej będącej skutkiem detonacji w przewodach pomiędzy zasobnikiem a młynem węglowym. Badania prowadzono w komorze fluidyzacyjnej z mniejszymi niż krytyczne prędkościami przepływu gazu. Wyniki pozwoliły na określenie wysokości złoża paliwowego w zasobniku przykotłowym, przy której jest emitowana najmniejsza porcja pyłu w strefie występowania utleniacza po przejściu fali ciśnieniowej. Zaprezentowana analiza pozwala na opracowanie skutecznej pasywnej metody zabezpieczania przeciwwybuchowego instalacji do mielenia i magazynowania pyłów.

EN

This paper presents the results of experimental investigations to determine the maximum level of fuel in the tank. The fuel level in the tank determines the amount of dust escaping over fuel during the transition fail a class effect of detonation pressure in the pipes between the container and coal mill. The study was conducted in a fluidized bed chamber to less than the critical speed of the gas flow. The results allowed us to determine the amount of fuel in the storage of coal for which the crossing of the pressure wave is emitted smallest unit of dust in the presence of oxidant. The presented analysis allows to develop an effective passive methods of explosion protection and storage of dust.

14

Analiza zmian udziału powietrza w przepływie przez pęczek rurowy skraplacza

Joachimiak M., Krzyślak P.

Journal of Mechanical and Transport Engineering

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2013

|

Vol. 65, No. 1

37--52

PL

Niniejszy artykuł jest poświęcony analizie zmian udziału masowego powietrza w przepływie przez pęczek rurowy skraplacza. Analizie poddano modelowy pęczek rurowy złożony z dwudziestu rzędów szeregowo umieszczonych rur o średnicach 28 mm. Obliczenia iteracyjne wykonano przy założeniu, że gazy wpływające do skraplacza mają ciśnienie 5000 Pa i prędkość 50 m/s. Założono również, że powietrze stanowi 1% masowy gazów wpływających do skraplacza i na każdym rzędzie rur wymieniana jest taka sama ilość ciepła. Wyznaczono udział masowy powietrza w kolejnych rzędach rur, a także wartości ciśnienia, temperatury, strat ciśnienia, współczynnika strat, prędkości, liczby Reynoldsa, gęstości gazów, strumienia masy gazów i ciepła parowania pary wodnej. Zauważono, że w ostatnich rzędach następuje znaczny wzrost udziału masowego powietrza w gazach przepływających przez skraplacz.

EN

This paper is devoted to the analysis of participation in the flow of air through the condenser tube bundle. The model tube bundle composed of twenty rows of serially arranged pipes with a diameter of 28 mm was analyzed. Iterative calculation was made on the understanding that the gas flowing into the condenser has pressure equal 5000 Pa and the speed equal 50 m/s. It was assumed that the air averages 1% by mass of gases flowing into the condenser and the same amount of heat is exchanged for each row of tubes. The mass fraction of air, the value of pressure, temperature, loss of pressure, loss factor, velocity, Reynolds number, gas density, mass flow of gas and the heat of vaporization of steam in the subsequent rows tubes were calculated. It was noted that in the last rows a significant increase of the mass fraction of air in gases flowing through the condenser.

15

The analysis of the calculation process related to labyrinth sealing with extraction

Joachimiak D., Joachimiak M., Krzyślak P.

International Journal of Applied Mechanics and Engineering

|

2013

|

Vol. 18, no. 4

1057--1066

EN

The work presents a calculation process enabling one-dimensional numerical calculations of labyrinth sealing. A DSV program determines the thermodynamic parameters of gas in the sealing chambers with extraction. The influence of the sealing length upon the stability of a matrix solution of the system of equations with the use of Cond(C) parameter is analysed. Next, the operation of the software extended with a module that enables determination of the initial pressure p0, to which the assumed mass flow for a set geometry and sealing length would correspond is discussed. The work analyzes Cond(C) and initial pressure values for various sealing lengths with an assumed leak value. The work also compares the values of static pressures on the extraction plane, as obtained from the measurements, to theoretically calculated values. The calculations and comparisons were made for various heights of incomplete sealing fissures.

16

Porównanie jednowymiarowych modeli obliczeniowych przepływu ściśliwego i nieściśliwego płynu w dławicy labiryntowej

Joachimiak D., Krzyślak P.

Zeszyty Naukowe Politechniki Poznańskiej. Maszyny Robocze i Transport

|

2011

|

Nr 64

51-67

PL

W artykule przedstawiono istotę działania uszczelnień labiryntowych oraz niektóre aspekty stosowania różnych wariantów ich konstrukcji. Publikacja zawiera opis modeli obliczeniowych, w których zakłożono przepływ izentalpowy. Pierwszy model uwzględnia przepływ ściśliwy, a drugi nieściśliwy. Dla założonego rodzaju gazu, jego parametrów termodynamicznych, zdefiniowanej geometrii i typu uszczelnienia za pomocą modeli wyznacza się początkowo rozkład liniowy spadku ciśnienia, a następnie rzeczywisty rozkład ciśnienia i wartości pozostałych parametrów termodynamicznych gazu. Określa się również prędkość i liczbę Macha w poszczególnych przewężeniach. W obliczeniach nie uwzględnia się lepkości płynu, pomijana jest również wymiana ciepła pomiędzy gazem a ściankami uszczelnienia.

EN

In the results of calculations of compressible model in article were compared was and incompressible for flow by labirynth seals. Near put the same the value of pressures before and for clearence seal: the course of fall of pressure, speed on length the seal as well as value of leakage differ considerably. Summing up it is possible to show apication considered computational models calculation. Incompressible model has first of all use in seal which liquid swims. From simplifying it can be applied to labirynth gas seals analysis near low differences of pressures. It is possible one dimensional compressible model apply to all labirynt seals in which it swims gauzes and we have the large differences of pressures. Introduced models make possible determination parameters thermodynamic flows through for defined seal geometry. The practically introduced computational tools will to be of service to designing to the stand project for the research of labirynth seals, as well as the foreseeing of measured thermodynamical values in definite points the designed seals on measuring position.

17

Performance analysis of small power plants with a backpressure or extraction-condensing steam turbines

Krzyślak P., Lampart P.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

|

2011

|

nr 140

123-130

EN

Two cogeneration steam turbine cycles for a biomass station are investigated - a cycle with a backpressure and an extraction-condensing turbine. The operation of these turbines is scrutinized for a given yearly distribution of heat demand from the healing network. The methodology employed here may serve as a model for broadened economic analysis and selection of an energy and economy effective variant of installation.

18

Calculation of labyrinth seals with extraction

Joachimiak D., Krzyślak P.

International Journal of Applied Mechanics and Engineering

|

2011

|

Vol. 16, no 1

5-14

EN

The paper presents a method for calculation of labyrinth seals with extraction. It involves a disorder of movement by interfering with the flow and bringing some irrelevant value of the mass stream out of a specific point of the labyrinth packing and outside the seal. It is described how to detect changes in the seal geometry by introducing a diagnostic parameter. The results of calculations are determined by an algorithm based on linearizations of de Saint - Venant equations.

19

Comparing N3-60 cascade exit angles obtained from tunnel measurements and numerical simulations

Biernacki R., Krzyślak P.

Polish Maritime Research

|

2010

|

nr 1

51-56

EN

The article compares the results of the measurements performed in the aerodynamic tunnel owned by the Czestochowa University of Technology and the numerical simulation done using the code FLUENT for a plane cascade of N3-60 profiles. The comparison study aims at assessing differences between the exit angles measured experimentally and those obtained from numerical calculations. Variable parameters in the measurements and the calculations were the relative pitch and the profile stagger angle. The measurements were performed in the flow of air. The same medium and having the same inlet parameters was assumed in the calculations. The calculations were performed in two dimensions for the compressible flow. The k-ĺ RNG turbulence model was used to complete the equation system. Comparing the measured and calculated results provides opportunities for assessing the range of differences between the experiment and the simulation. The obtained results and formulated conclusions will find the application not only in the power industry, but also in the shipbuilding industry for analysing the operation of steam and gas turbines used as main and auxiliary propulsion systems on both merchant vessels and battle ships.

20

Comparative analysis of energy potential of three ways of configuration of a condenser power plant thermal cycle

Chmielniak T., Krzyślak P.

Polish Maritime Research

|

2008

|

nr 4

30-36

EN

A theoretical, comparative analysis of three configuration ways of a condenser power plant thermal cycle is shown in the work. A new regeneration & separation preheater and its application in a thermal cycle is presented. Results obtained allow to compare all three analysed configurations efficiencies.