Wyniki wyszukiwania - BazTech

1

Identification of the liquid turbulent flow based on experimental methods

Talaga Jan, Duda Piotr

Archives of Thermodynamics

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2020

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Vol. 41, no 3

91--102

EN

This paper presents the results of experimental testing of parameters of the flow of an agitated liquid in a stirred tank with an eccentrically positioned shaft and with a Rushton turbine. The investigations were focused on the impact of the stirrer shaft shift in relation to the stirred tank vertical axis on the agitated liquid mean velocities and the liquid turbulent velocity fluctuations, as well as on the turbulence intensity in the tank. All the experiments were carried out in a stirred tank with the inner diameter of 286 mm and a flat bottom. The adopted values of the shaft eccentricity were zero (central position) and half the tank radius. The liquid flow instantaneous velocities were measured using laser Doppler anemometry.

2

Numeryczno-doświadczalna weryfikacja projektu analitycznego wentylatora osiowego

Majcher Maciej, Wrzesień Stanisław, Frant Michał

Mechanik

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2019

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R. 92, nr 8-9

591--593

PL

Porównano podstawowe charakterystyki wentylatora osiowego uzyskane za pomocą trzech metod badawczych: analitycznej, doświadczalnej i numerycznej. Przeanalizowano charakterystyki przyrostu ciśnienia całkowitego, sprawności i mocy. Omówiono wpływ odchylenia geometrii wyprodukowanego wieńca wirnikowego od założeń wynikających z projektu analitycznego. Potwierdzono poprawność zastosowanego schematu projektowania wentylatora osiowego opartego na metodach analitycznych, numerycznych i doświadczalnych.

EN

The paper presents a comparison of basic axial fan characteristics obtained by three research methods: analytical, experimental and numerical. Characteristics of the total pressure, efficiency and power were analyzed. The influence of the geometry deviation of the manufactured rotor rim from the assumptions resulting from the analytical design was discussed. The correctness of the axial fan designing scheme based on analytical, numerical and experimental methods was confirmed.

3

A Numerical Investigation into the Effect of Blade Trailing-Edge Thickness on the Performance of Axial Fans

Majcher M., Wrzesień S., Frant M., Omen Ł.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2018

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Vol. 9, Nr 4 (34)

71--84

EN

This paper presents the results of a numerical investigation into the effect of blade trailing-edge thickness and shape on the performance of a rotor ring model of axial fan. The numerical simulations carried out under this investigation provided the performance characteristics of efficiency, working medium power, and total pressure increase in the function of the volumetric flow rate of the rotor ring. The investigated blade trailing-edge thickness values were 1 mm, 2 mm, and 3 mm. The models for the simulation series were developed with rounded and sharp blade trailing edges, for all thickness values thereof. The rounded trailing blade edges were modelled in the form of an arc over which the conditions of tangency with the upper and lower contours of the airfoil were imposed. The blades of the modelled blade fan were designed with the NACA 65-810 airfoil. To verify the applied turbulence model and mesh settings, experimental tests of the model rotor ring were performed on an axial fan test bed. The obtained experimental data was compared with numerical results. The results showed a significant impact of the thickness and shape of the blade trailing edge on the performance characteristics of axial fans.

PL

W niniejszej pracy przedstawiono wyniki numerycznego badania wpływu grubości i kształtu krawędzi spływu łopatki wirnikowej na charakterystyki pracy modelowego wieńca wirnikowego wentylatora osiowego. W toku symulacji numerycznych uzyskiwano charakterystykę sprawności, mocy oraz przyrostu ciśnienia całkowitego w funkcji objętościowego natężenia przepływu przez wieniec wirnikowy. Przyjęte do analizy grubości krawędzi spływu łopatki wynosiły 1 mm, 2 mm, 3 mm. Modele do serii symulacji numerycznych wykonano dla zaokrąglonych i niezaokrąglonych krawędzi spływu o podanych wyżej grubościach. Zaokrąglone krawędzie spływu odwzorowywano w postaci łuku, na który narzucono warunki styczności do górnego i dolnego obrysu profilu definiującego kształt łopatki. Łopatki modelowego wieńca wirnikowego zbudowano w oparciu o profil NACA 65-810. Na potrzeby sprawdzenia poprawności przyjętego modelu turbulencji oraz ustawień siatki przeprowadzono badania doświadczalne modelowego wieńca wirnikowego na stanowisku do badań wentylatorów osiowych. Uzyskane dane eksperymentalne zestawiono z wynikami numerycznymi. Przedstawione wyniki wykazały istotny wpływ grubości i kształtu krawędzi spływu łopatki wirnikowej na charakterystyki pracy wentylatora osiowego.

4

Zastosowanie nowoczesnych tworzyw sztucznych do budowy wysokoobrotowych maszyn przepływowych

Żywica G., Kaczmarczyk T.Z., Ihnatowicz E.

Mechanik

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2018

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R. 91, nr 7

508--510

PL

Omówiono zagadnienia związane z doborem tworzyw sztucznych na wybrane elementy wysokoobrotowych maszyn przepływowych. Oprócz kryteriów stosowanych przy doborze materiału przedstawiono przykład analizy wytrzymałościowej tarczy wirnikowej z tworzywa sztucznego. Celem tych prac było zastąpienie powszechnie stosowanych stopów metali nowoczesnymi tworzywami sztucznymi, co może się przełożyć na skrócenie czasu produkcji i obniżenie kosztów.

EN

Discussed are issues related to the selection of plastics for manufacturing chosen components of high-speed fluid-flow machinery. In addition to discussing the criteria used for material selection, an exemplary strength analysis of a rotor disk made of plastic was presented. The work carried out was aimed at replacing commonly used metallic alloys with modern plastics, which in turn may shorten production time and reduce costs.

5

Test stand for the experimental investigation of turbochargers with 3d printed components

Andrearczyk A., Bagiński P., Żywica G.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 2

397--404

EN

The paper discusses the universal test stand which allows determining the characteristics of turbochargers. Currently, there are works carried out in the world aimed to develop innovative fluid-flow machines, made partly with the use of rapid prototyping technology. This type of manufacturing technology allows reducing production time and costs in comparison to conventional methods of prototyping. This article also discusses start-up tests of the experimental test stand using a commercial turbocharger and the comparison between calculated and experimental results. In this paper, there are also described some modifications of the test stand, made prior to the start-up test, which were necessary to get more accurate characteristics of turbochargers. This work is an introduction to the investigation on turbomachines, whose elements were manufactured using the rapid prototyping technology.

6

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

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2017

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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.

7

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.

8

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.

9

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

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2013

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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.

10

Calculation of labyrinth seals with extraction

Joachimiak D., Krzyślak P.

International Journal of Applied Mechanics and Engineering

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2011

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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.

11

Diagnostyka zniszczeń erozyjnych wirnika sprężarki gazów NOx, ułożyskowanego ślizgowo, metodą komputerowej analizy nieliniowej

Banaszek S., Łuczak M.

Problemy Eksploatacji

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1999

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nr 2

21-30

PL

W niniejszym artykule przedstawiono wyniki komputerowej analizy wpływu erozji wału na stan dynamiczny trzystopniowej sprężarki gazów NOX. Z przyczyn technologicznych oraz z powodu warunków termodynamicznych, wewnątrz sprężarki tworzy się kwas azotowy, który kontaktując się z materiałem wału za pierwszym stopniem sprężarki powoduje jego erozję. Celem pracy było znalezienie na drodze obliczeń teoretycznych głębokości wżeru erozyjnego, przy której następuje zadziałanie systemu monitorującego (sygnalizacja i wyłączenie). Obliczenia prowadzono za pomocą opracowanych w Instytucie Maszyn Przepływowych PAN w Gdańsku programów komputerowych systemu MESWIR w oparciu o model MES wirnika sprężarki oraz nieliniowe modele łożysk ślizgowych.

EN

An article presents results of computer analysis of an erosion influence on the three-stage NOx compressor dynamic state. Because of technological regimes and thermodynamic conditions the nitric acid was formed behind the first stage. It was leaking under the preventive bush, inducing an erosion of the shaft. The aim of the analysis was to find the depth of the erosion pit inducing the distress signal and alarm (cut-out) of the vibration monitoring system. The computer analysis was using the computer code system called MESWIR, originally invented in the Institute of Fluid-Flow Machinery in Gdansk. This system requires a finite elements model of rotor and allows to analyse a non linear dynamic problems using an elastodiathermic slide bearings model. The results of computations show us that even the erosion pit depth equal to 25% reduction of shaft diameter does not induce the increase of vibrations. A dangerous escalation of vibrations occurs when the shaft diameter reduction is greater than 30-35%.