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1
Content available remote Reconstruction of turbomachines on the basis of the flow structure visual diagnostics
Arsiri V., Kravchenko O.
Mechanics and Mechanical Engineering
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2018
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Vol. 22, nr 2
405--414
EN
The indicator of the quality of modern turbomachines is only the coefficient of efficiency, which characterizes the ratio of the useful work of compressors or fans to the energy expended on the drive. For the analysis of the quality of the motion, processes in flow parts, the values of resistances are used which are difficult to be considered as an indicator of the efficiency of dynamic processes. The report presents the results of visual diagnostics of the structure of flows during the movement in the elements of turbomachines, as well as options for improving the geometry of the flow parts - in the inlet pipes, impellers. For the analysis of the efficiency of the motion of liquids and gases in flowing parts, a calculated index is proposed - the coefficient of hydraulic efficiency of dynamic processes. The joint use of two indicators - the efficiency of transformation of different types of energy (efficiency of turbomachines) and the efficiency of dynamic processes in flowing parts allows us to develop and to analyze the results of reconstruction of turbomachines. Reconstruction of turbomachines with the purpose of improving the geometry of the flow parts provides an increase in productivity of turbines, compressors, fans and pumps, while reducing the specific energy consumption for the processes of compression and transport of liquids and gases. Optimization of turbomachines flow parts based of flow structure visual diagnostics allows to reduce noise and vibration, as well as to solve other problems.
2
Content available 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.
3
Content available 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.
4
Content available Comparative analysis of the results of gas flow in a labyrinth seal for a numerical and theoretical model
Kaszowski P., Dzida M.
Journal of Polish CIMAC
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2014
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Vol. 9, no 2
117--125
EN
Labyrinth seals are an important component of gas and steam turbines design. Many calculation models are available in order to determine the thermodynamic parameters of gas along the seal length: starting with models based on an analytical solution to the problem of gas flow through a seal to numerical models resulting in numerical data and visualizations of conditions inside the seal. In this article the results of calculations made using the Fanno model and the Saint-Venant's Principle with the k-epsilon model in Ansys Fluent are compared.
5
Content available 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.
6
Content available remote Non-linear singular integral equations analysis for unsteady cascade aeroelasticity applied in turbomachines
Ladopoulos E. G.
Archives of Mechanics
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2013
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Vol. 65, nr 1
45-53
EN
A two-dimensional unsteady cascade aeroelasticity is introduced for the investigation of flow fields of turbomachines (gas or steam). Especially, the velocity field around a cascade of airfoils is determined, while such a problem is reduced to the solution of a non-linear multidimensional singular integral equation when considering harmonic time dependence between the motions of adjacent blades of the turbine. Consequently, a general non-linear model is investigated by proposing an “innovative” and “groundbreaking” method. An application is finally presented by considering a special description of the velocity field and therefore such a field is determined for arbitrary geometry and arbitrary interblade phase angle.
7
Content available remote 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.
8
Content available Historia i tendencje rozwojowe napędów lotniczych
Opara T.
Silniki Spalinowe
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2006
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R. 45, nr 4
3-18
PL
W opracowaniu przedstawiono etapy rozwoju napędów lotniczych, począwszy od silników tłokowych do trójwirnikowych silników turbinowych. Ograniczenia w zakresie prędkości i wysokości lotu, jakie wynikały z zastosowania klasycznego układu silnik tłokowy-śmigło, stały się impulsem do podjęcia prac badawczych nad napędem odrzutowym. Odzwierciedleniem rywalizacji w tym zakresie były dokonania twórców pierwszych silników odrzutowych: F. Whitlea i H. von Ohaina. Napęd turbinowy (odrzutowy, śmigłowy i śmigłowcowy) zdominował lotnictwo wojskowe i cywilne już w drugiej połowie XX wieku. W 1960 r. rozpoczęła się era silników dwuprzepływowych o korzystniejszych parametrach eksploatacyjnych z elektronicznymi i cyfrowymi układami automatycznej regulacji. Dalszy rozwój silników turbinowych wiąże się z zastosowaniem jakościowo nowych materiałów (zwłaszcza zaś kompozytów), optymalizowaniem kształtów łopatek sprężarki i turbiny oraz technologii ich wytwarzania. W artykule przedstawiono zmiany konstrukcyjne prowadzące do ograniczenia destrukcyjnych skutków zasysania ciał obcych. Wskazano na możliwość zwiększenia manewrowości samolotów przez zastosowanie wektorowania ciągu. Omówiono perspektywy rozwoju turbinowych napędów lotniczych.
EN
This paper discusses stages of development of air propulsion from piston engines up to three-rotor turbine ones. Limitations in speed and altitude of flight, caused by traditional system of a piston engine and an airscrew, became an impulse to conduct research on jet propulsion. Accomplishments of the designers of the first jet-propelled engines: F. Whitle and H. von Ohain are a reflection of rivalry in this field. In the second half of the 20th century turbine propulsion (turbojet, turboprop and helicopter engines) dominated air force and civil aviation. In 1960 the age of turbofans began, owing to better operating properties and electronic and digital systems of automatic regulation. Further development of turbine engines is connected with application of qualitatively new materials (particularly composites), optimization of the shape of compressor and turbine blades and technologies of their production. The paper discusses design changes decreasing the destructive effects of foreign matter suction and indicates the possibility of increasing the maneuverability of airplanes by thrust vectoring. Finally, development prospects of turbine propulsion are analyzed.
9
Content available remote Numerical analysis of turbine blading vibrations
Vorobyev Yu. S., Tyshkovets O. V., Janecki S.
Transactions of the Institute of Fluid-Flow Machinery
|
2003
|
nr 114
229-236
EN
Turbomachine blading vibrations are one of the most important problems. They are the reason for turbine damages. Numerical methods of vibration analysis are useful in prediction of the frequencies, the distribution and localisation of stress in blades. Accordingly, in this work numerical methods and results of computations are performed for various types of blading.
10
Konstrukcyjno-technologiczne aspekty spawalności stali typu 17-4PH w maszynach przepływowych
Nowacki J., Łukojć A.
Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika
|
2000
|
Z. 72
171-177
PL
W wyniku analizy konstrukcji i technologii spawania kół wirników sprężarek promieniowych wykazano możliwość zastosowania stali 17-4PH na elementy spawane tych kół. Nowy materiał został zastosowany w przemyśle z dobrym skutkiem. Spawanie przeprowadzono dwiema metodami: ręczne elektrodą otuloną (111) i półautomatycznie drutem proszkowym (114), następnie złącza poddano wybranym zabiegom obróbki cieplnej. Rozważano wpływ obróbki cieplnej złączy na ich właściwości wytrzymałościowe i przeciwkorozyjne. Najlepsze właściwości wytrzymałościowe i przeciwkorozyjne wykazały złącza poddane przesycaniu w temperaturze 1040 stopni C/2h i starzeniu w temperaturze 620 stopni C/2h i złącza poddane odprężeniu w temperaturze 620 stopni C/2h. Z punku widzenia ekonomicznego i właściwości mechanicznych oraz przeciwkorozyjnych najkorzystniejszym warunkiem obróbki cieplnej spawanego koła wirnika sprężarki promieniowej jest odprężanie po spawaniu.
EN
Welding tests were carried out on the age-hardened steel of the 17-4 PH type. The ininvestigation was related to possibilities of joining centrifugal compressor impeller parts as important elements of turbo machines. The method has been applied in industry. Two means of welding (111) and (114) as well as following heat treatment have been considered. The best results: high tensile strength and high corrosion resistance were obtained for over saturating of the welded wheel in temperature 1040 degrees C/2h followed by ageing in 620 degrees C/2h or only annealing after welding.
11
Expectation of the brazed joint application to the turbomachines.
Nowacki J., Wysiecki M.
Postępy Technologii Maszyn i Urządzeń
|
1999
|
Vol. 23, nr 3
103-112
EN
Vacuum brazing tests were carried out on the age-hardened steel of the 14-5 PH type using the 82Au 18Ni solder. The investigation was related to possibilities joining centrifugal compressor impeller parts as an important example of turbomachines. The obtained joint has multilayer structure and it consists of two kinds of Au-Ni solid solutions: one is rich in gold and the other - rich in nickel. The influence of roughness of the surfaces to be joined and the distance between them on the joint strength have been determined. The maximum tensile strength (Rm=1260 MN/m2) was obtained for the joints of polished (Ra=0,04) surface without any distatnces elements, brazed in the temperature 1293 K for 2 hours and then aged in the temperature 723 K for 2 hours. Satisfactory result of brazing of high dimensional impeller parts is possible by a careful design, material and the brazing cycle selection. It is possible to control the joint thickness by roughness of surfaces to be joint. It allows to resign of distance elements what facilitates preparation machine elements to the brazing.
PL
Próby lutowania próżniowego przeprowadzono na stali utwardzanej wydzieleniowo typu 14-5 PH z zastosowaniem lutu 82Au 18Ni. Badania dotyczyły części wirnika sprężarki promieniowej jako ważnego przykładu maszyny przepływowej. Wytworzone połącznia mają wielowarstwową strukturę składającą sie z dwóch rodzajów roztworów stałych Au-Ni, jednego bogatego z złoto, drugiego bogatego w nikiel. Określono wpływ chropowatości i odległości powierzchni łączonych na właściwości mechaniczne. maksymalną wytrzymałość na rozciąganie spojenia (Rm=1260 MN/m2) otrzymano dla powierzchni polerowanych (Ra=0,04) łączonych na styk, lutowanych w temperaturze 723 K przez 2 h. Satysfakcjonujące rezultaty lutowania części wirników dużych rozmiarów są możliwe przez staranny dobór konstrukcji, materiału i cyklu lutowania. Jest możliwa kontrola grubości połączenia za pomocą chropowatości powierzchni łączonych, co pozwala na rezygnację z elementów dystansujących.
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