Temat: tip - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Experimental study on dynamic structure of propeller tip vortex
Autorzy:: Li, Guangnian
Chen, Qingren
Liu, Yue
Powiązania:: https://bibliotekanauki.pl/articles/260305.pdf
Data publikacji:: 2020
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: propeller
blade tip
tip vortex
PIV
Opis:: Propeller cavitation is a main source of fluctuating pressure and noise induced by propellers, and the tip vortex cavitation is the principal source. The present study measures the flow fields near the blade tip using the 2D-PIV technique. The experimental setup and scheme are introduced. We monitor the process of generation and shedding of the propeller tip vortex in real time and analyse the dynamic structure of the tip vortex by testing the propeller wake field under different phases of the axial plane. The distribution characteristics of radial and axial velocity are also analysed. The influence range and the vorticity of the tip vortex and trailing vortex are obtained. All of the measured quantitative data are useful for future propeller design.
Źródło:: Polish Maritime Research; 2020, 2; 11-18
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: The unsteadiness of tip clearance flow and its effect to stability of transonic axial compressor
Nieustaloność przepływu w szczelinie wierzchołkowej i jej wpływ na stabilność pracy przydźwiękowej sprężarki osiowej
Autorzy:: Hu, J. F.
Zhu, X. C.
Ou-Yang, H.
Tian, J.
Wu, Y. D.
Qiang, X. Q.
Zhao, G.
Du, Z. H.
Powiązania:: https://bibliotekanauki.pl/articles/281445.pdf
Data publikacji:: 2013
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: tip leakage flow
compressor
stability
Opis:: The steady and unsteady RANS simulations of a transonic compressor rotor (NASA rotor 37) are performed to investigate the tip clearance flow characteristic and correlations between tip leakage flow and compressor stability. For steady simulations, the results are compared with the aerodynamic probe and laser anemometer data. The speed lines and span-wise aerodynamic parameters agree well with the experimental data. On the other hand, the tip clearance flow of unsteady simulations are analysed clearly at a near stall condition. The results show that there is a mass flow rate boundary. The tip clearance flow oscillates substantially with a frequency about 50% BPF when the mass is less than that, which is caused by tip clearance flow, shock, and the interaction between them and the oncoming flow. The interface between the oncoming flow and clearance flow shifts forward, and the tip clearance flow may spill over into the adjacent blade passage as the mass flow decreases, which may results in the spike stall inception.
W pracy przedstawiono symulacje stanu ustalonego i nieustalonego przydźwiękowej sprężarki osiowej (turbina NASA 37) z zastosowaniem metody Reynoldsa uśredniania równań Naviera-Stokesa (RANS) w celu zbadania charakterystyki przepływu w szczelinie wierzchołkowej oraz określenia zależności pomiędzy stratami związanymi z upływem w tej szczelinie a stabilnością pracy sprężarki. Wyniki symulacji stanu ustalonego porównano z danymi doświadczalnymi uzyskanymi za pomocą sondy aerodynamicznej i laserowego wiatromierza. Wyznaczone wzdłuż rozpiętości sprężarki linie prędkości przepływu i jego parametry aerodynamiczne okazały się zgodne z danymi doświadczalnymi. W przypadku symulacji stanu nieustalonego, analizę przepływu w szczelinie wierzchołkowej przeprowadzono dla warunków bliskich oderwania, tj. utraty wydajności sprężarki, wyznaczając graniczny wydatek przepływu dla takiej sytuacji. Poniżej tej granicznej wartości, zmiany przepływu w szczelinie oscylują z częstotliwością sięgającą 50% częstotliwości przejścia łopatek (tzw. BPF), co jest konsekwencją interakcji wywołanej zderzeniem przepływu z falą napływową w szczelinie wierzchołkowej. Powierzchnia tej interakcji przesuwa się do przodu, a sam przepływ może rozpaść się na fragmenty znajdujące ujście w kanałach przyległych łopatek. Zjawisko to zachodzi przy malejącym wydatku, a to z kolei może indukować oderwanie przepływu skokowymi zmianami mocy współpracującego silnika.
Źródło:: Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 431-438
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Nano-hardness of the material of thin layers of the injector tip depending on the depth under the precisly finished co-operating surfaces
Autorzy:: Miszczak, A.
Kuznetsova, T.
Czaban, A.
Powiązania:: https://bibliotekanauki.pl/articles/243108.pdf
Data publikacji:: 2015
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: nanohardness
Young's modulus
nano-identer
injector tip nozzle
injector spray pattern
injector tip needle
Opis:: In this paper, the authors present the results of experimental studies of the nano-hardness and Young's modulus of the injector spray pattern body and needle (the tip of the injector). The nano-hardness of a thin-layer of precisely finished co-operating surfaces was tested according to the depth below the surface of the sample (deep into the material). The quality of precisely finished surfaces of a fuel infector has a very large impact on the proper operation of a diesel engine. Both, the needle and the body of the injector spray pattern, are individually adjusted and lapped to maintain the proper gap between them. The gap between the needle and the injector tip body affects the proper dosage and quality of the sprayed fuel. Impurities in the fuel are of the same order of magnitude or even greater than this gap. Hard particles that penetrate between the side surfaces of the needle and body of the injector tip could result in scratching, which generate leaks and drops of injection pressure, increased fuel consumption, poor spraying of fuel, leaking of fuel to the lubricating oil and reduction of its operating properties. The hardness of the precisely finished surfaces of the injector is essential in the process of wear of these surfaces. The aim of the study was to determine the hardness and Young's modulus of thin layers of precisely finished co-operating surfaces of injector tip and estimation of the thickness of these layers. The nano-hardness measurements were made with the Hysitron TI 950 TriboIdenter, where the test is conducted using a nano-indenter with a mechanical method. The device allows selecting from several to several dozen of measurement points and performs automatic measurement of nano-hardness and Young's modulus in the indicated locations. The study concerns the tip (body and needle) of the non-used Bosch DLLA 160 S 1305 injector. The presented results can be used to develop some new methods of coating the co-operating surfaces with the hard thin layers, e.g. the use of titanium in order to decrease wear and increase scratching resistance.
Źródło:: Journal of KONES; 2015, 22, 3; 155-160
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Two dimensional model of CMM probing system
Autorzy:: Ali, Salah H.R.
Powiązania:: https://bibliotekanauki.pl/articles/950738.pdf
Data publikacji:: 2010
Wydawca:: Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:: CMM
trigger probe
stylus tip
tip root errors
and two-dimensional-model (2DM)
Opis:: A coordinate measuring machine (CMM) as an automation technology is playing the key role in the modern industry to improve the measurement accuracy. Accurate probing that is computer controlled is the current trend for the next generation of coordinate metrology. However, the CMM probing system is limited by its dynamic root errors that may markedly affect its response characteristics. In this paper, dynamic response errors of CMM measurements have been analyzed. The adopted probe stylus sizes throughout the course of measurements are found to cause some waviness errors during CMM operations due to each of the prescribed angle of the probe tip contact point with the specimen surface and the radius of the stylus tip. Variations in the geometry of the stylus have their consequent effects on its inherent intrinsic dynamic characteristics that in turn would cause relevant systematic root errors in the resulted measurements. Unforeseeable geometrical errors of a CMM using a ductile touch-trigger probing system have been characterized theoretically. These results are analyzed in order to investigate the effect of the dynamic root errors in the light of six probe stylus tip of the situation into account when assessing the accuracy of the CMM measurements. Analytical approaches have been applied on a developed two dimensional model (2DM) of stylus tip to demonstrate the capability of such approaches of emphasizing the root error concept using the strategy of CMM ductile trigger type of probe.
Źródło:: Journal of Automation Mobile Robotics and Intelligent Systems; 2010, 4, 2; 3-7
1897-8649
2080-2145
Pojawia się w:: Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Development of an on-line damage detection, discrimination and tracking system for the spin rig facility
Autorzy:: Przysowa, R.
Bereś, W.
Carnegie, C.
Powiązania:: https://bibliotekanauki.pl/articles/241879.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: disc crack
disc health monitoring
vacuum spin testing
tip timing
tip clearance
low cycle fatigue
Opis:: The main goal of the work reported here was to expand the capability of the NRC-Aerospace spin rig by adding an on-line damage detection, discrimination and tracking system, and to develop necessary expertise that will allow for optimizing the NDE inspection periods of gas turbine engine components in this facility and minimizing undetected crack nucleation and growth and possibility of catastrophic failures. Passive eddy-current sensors and a data acquisition system able to simultaneously measure blade deflection and tip clearance were selected to monitor health of rotating components. Before application of the system in the spin rig, the system was tested with a rotor rig to check sensor responses to deliberately induced changes in blade tip positions in both radial and circumferential directions. The monitored disc had 12 bolts simulating aerofoils that could be turned into threaded holes to extend or shorten the protruding parts of the bolts. On the other hand, bolt vibration was not excited and analysed during the experiment. Lessons learned on the rotor rig are used to prepare and plan spin tests in vacuum chamber.
Źródło:: Journal of KONES; 2017, 24, 2; 197-209
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Uyghurs of Syria: Significance for the Syrian Conflict and International Implications
Ujgurzy w Syrii – znaczenie dla konfliktu syryjskiego i implikacje międzynarodowe
Autorzy:: Mazur, Przemysław
Powiązania:: https://bibliotekanauki.pl/articles/22435850.pdf
Data publikacji:: 2023-09-30
Wydawca:: Wydawnictwo Adam Marszałek
Tematy:: Uyghurs
Syria
terrorism
Turkey
China
ISIS
Turkistan Islamic Party (TIP)
Ujgurzy
TIP
terroryzm
Turcja
Chiny
Opis:: The main objective of the article was to determine whether the Uyghurs were a relevant group in the Syrian conflict, i.e., whether they were numerous, well-organized and determined enough to take the fight to the Syrian army or other non-state actors or cooperate with them. Several levels of analysis were carried out in this article. Firstly, article aimed to show where the Uyghurs in Syria came from. Secondly, the following section assessed their importance to the Syrian conflict, as well as who they worked with and fought against. Thirdly, it analysed whether their military and political involvement could have an impact on the international situation. Last but not least, the fate of Uyghurs, especially those who left for Syria, was discussed. The latter issue is also a question about Syria, its fate and place in the politics of other countries.
Głównym celem artykułu było ustalenie, czy Ujgurzy byli istotną grupą w konflikcie syryjskim, innymi słowy – czy byli na tyle liczni, dobrze zorganizowani i zdeterminowani, by podjąć walkę z wojskami syryjskimi czy innymi aktorami niepaństwowymi lub z nimi współpracować. W artykule przeprowadzono analizę na kilku poziomach. Po pierwsze, artykuł miał na celu ustalenie, z jakich przyczyn Ujgurzy wyemigrowali do Syrii. Po drugie, oceniono ich znaczenie dla konfliktu syryjskiego, a także to, z kim współpracowali i z kim walczyli. Po trzecie, przeanalizowano, czy ich militarne i polityczne zaangażowanie może mieć wpływ na sytuację międzynarodową. Na koniec omówiono losy Ujgurów, zwłaszcza tych, którzy wyjechali do Syrii. To ostatnie zagadnienie stanowi też pytanie o Syrię, jej dalsze losy i miejsce w polityce innych państw.
Źródło:: Athenaeum. Polskie Studia Politologiczne; 2023, 79; 194-214
1505-2192
Pojawia się w:: Athenaeum. Polskie Studia Politologiczne
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Numerical study of stall inception in a transonic axial compressor rotor based on the throttle model
Autorzy:: Zhu, X.
Liu, B.
Hu, J.
Shen, X.
Powiązania:: https://bibliotekanauki.pl/articles/280516.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: stall
axial compressor
throttle
tip clearance flow
Opis:: The goal of the current paper is to investigate inner flow behavior on stall inception in a transonic compressor rotor. The stall inception process is numerically carried out by unsteady 3-D simulations based on the throttle model. The current study shows that stall starts from the tip of the blade, and stall cell extends to the axial, circumferential and radial directions. Through the comparison of flow transition characteristics at different flow rate conditions, the interface between the incoming flow and tip clearance flow shifts forward to the upstream as the mass flow decreases. Eventually, the shock detaches from the blade leading edge, and tip clearance flow spills into the adjacent blade passage, thus stall happens in the affected blade passages.
Źródło:: Journal of Theoretical and Applied Mechanics; 2015, 53, 2; 307-316
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Dynamic interaction of the cavitating propeller tip vortex with the rudder
Autorzy:: Szantyr, J. A.
Powiązania:: https://bibliotekanauki.pl/articles/260364.pdf
Data publikacji:: 2007
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: propeller blades
rudder
cavitating
tip vortex shed
Opis:: The hydrodynamic interaction between the ship propeller and the rudder has many aspects. One of the most interesting is the interaction between the cavitating tip vortex shed from the propeller blades and the rudder. This interaction leads to strongly dynamic behaviour of the cavitating vortex, which in turn generates unusually high pressure pulses in its vicinity. Possibly accurate prediction of these pulses is one of the most important problems in the hydrodynamic design of a new ship. The paper presents a relatively simple computational model of the propeller cavitating tip vortex behaviour close to the rudder leading edge. The model is based on the traditional Rankine vortex and on the potential solution of the dynamics of the cylindrical sections of the cavitating kernel passing through the strongly variable pressure field in the vicinity of the rudder leading edge. The model reproduces numerically the experimentally observed process of initial compression of the vortex kernel in the high pressure region near the stagnation point at the rudder leading edge and subsequent explosive growth of the kernel in the low pressure region further downstream. Numerical simulation of this process enables computation of the additional pressure pulses generated due to this phenomenon and transmitted onto the hull surface. This new numerical model of the cavitating tip vortex is incorporated in the modified unsteady lifting surface program for prediction of propeller cavitation, which has been successfully used in the process of propeller design for several years and which recently has been extended to include the effects of propeller – rudder interaction. The results of calculations are compared with the experimental measurements and they demonstrate reasonable agreement between theory and physical reality.
Źródło:: Polish Maritime Research; 2007, 4; 10-14
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Optimization of tip seal with honeycomb land in LP counter rotating gas turbine engine
Autorzy:: Wróblewski, W.
Dykas, S.
Bochon, K.
Rulik, S.
Powiązania:: https://bibliotekanauki.pl/articles/1943216.pdf
Data publikacji:: 2010
Wydawca:: Politechnika Gdańska
Tematy:: tip seal
LP turbine
honeycomb land
optimization
Opis:: The goal of the presented work is an optimization of the geometrical configuration of the tip seal with a honeycomb land, to reduce the leakage flow in the counter-rotating LP turbine of a contra-rotating open rotor aero-engine. This goal was achieved with the use of the Ansys-CFX commercial code and an in-house optimization procedure. The detailed studies including the mesh influence, the stages of the computational domain simplification, and geometry variants are discussed. The optimization process is based on a single objective genetic algorithm (SOGA). The automatic grid generation process and the CFD calculations are based on scripts prepared under the Ansys-ICEM and Ansys-CFX software. The whole procedure is written in the Visual Basic for Applications language (VBA), which allows a direct access to the CAD software with the use of macros and allows a proper connection between the CAD environment and the CFD software. The described algorithm allows parallel computing. In addition to the optimization studies, a sensitivity analysis was also performed. For this purpose, the Elementary Effects Method (EEM) was used. This paper was written within the DREAM European project (Validation of Radical Engine Architecture Systems) of the 7th Framework Program of the European Union.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 3; 189-207
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Study of topology and vortex structure in turbine cascades with tip clearance under different incidence angles
Badania topologii i struktury wirów palisady turbiny z luzem wierzchołkowym przy różnych kątach natarcia
Autorzy:: Yan, P. G.
Qiang, X. Q.
Teng, J. F.
Han, W. J.
Powiązania:: https://bibliotekanauki.pl/articles/279519.pdf
Data publikacji:: 2013
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: turbine cascade
tip clearance
topological rules
experimental study
Opis:: Three sets of conventional straight, positive curved and negative curved turbine cascades with tip clearance were tested with experimental measurement. The impact of incidence angles and blade bending on the tip leakage was studied under larger clearance (0.036 of span). An ink trace visualization of the wall flow and topology theory was adopted and thus the topological structures of the blade surface, the upper and lower end wall were analyzed in this paper. It was found that, compared with the same cascade under the zero incidence angle, the saddle points all move to the upstream, the scope of the separation expands along the flow and span direction, and the separation line of the upper and lower passage vortex climb to the middle span of the blade when the flow incidence angle increased from zero to 20º. Under the condition of zero and 20º incidence angle, the positive curved blade will eliminate the upper passage vortex. The numbers of singular points are reduced and the interaction loss between the passage vortex and the leakage vortex is greatly reduced too. On the other hand, it also strengthens the blocking effect of the end wall cross flow on the leakage flow, thereby reduces the relative leakage flow rate.
W pracy zaprezentowano wyniki pomiarów eksperymentalnych trzech zestawów konwencjonalnych palisad turbin o prostym, dodatnio i ujemnie zakrzywionym profilu. Zbadano wpływ kąta natarcia oraz efekt zginania łopatek na straty wskutek upływu przy luzie wierzchołkowym sięgającym 3.6% rozpiętości łopatek. Do analizy zastosowano wizualizację śladów pozostawianych barwnikiem oraz teorię topologii, tj. struktur topologicznych reprezentujących powierzchnię łopatki oraz górnej i dolnej ściany krańcowej. Zaobserwowano, że w porównaniu do analogicznej palisady o zerowym kącie natarcia wszystkie punkty siodłowe przesuwają się w gorę przepływu, a obszar oderwania strugi rozszerza się wzdłuż promienia łopatki. Jednocześnie granica oderwania górnego i dolnego wiru przemieszcza się ku środkowi łopatki, gdy kąt natarcia narasta od zera do 20◦. Przy tych granicznych wartościach kąta natarcia łopatki o dodatniej krzywiźnie profilu eliminują górny wir podczas przejścia. Ponadto okazało się, że liczba punktów osobliwych zmniejszyła się podobnie, jak osłabiła się interakcja pomiędzy wirami przejścia i wirami upływu. Stwierdzono, że wzmacnia to efekt blokowania upływu poprzecznym przepływem na krańcowej ścianie łopatki, co ostatecznie redukuje straty indukowane upływem.
Źródło:: Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 363-373
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: Measuring fan speed using the impeller tip pressure method
Pomiar prędkości obrotowej wentylatora metodą oznaczania ciśnienia na końcówce wirnika
Autorzy:: Li, Y. M.
Chen, K. Y.
Powiązania:: https://bibliotekanauki.pl/articles/348569.pdf
Data publikacji:: 2012
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:: końcówka wirnika
ciśnienie na końcówce wirnika
zmiany ciśnienia
prędkość obrotowa wentylatora
impeller tip
tip-pressure
pressure pulsation
fan speed
Opis:: The accurate measurement of fan speed is impact in the fan performance test experiments. As there is some relationship between the impeller tip pressure pulse frequency and speed of the impeller, the paper proposed a new impeller tip speed measurement method through counter-rotating fan speed measurement studies. The use of pressure sensors, data acquisition cards and programming technologies to measure the speed of reading directly integrated into the previous fan performance automated test systems was also presented. This proves that this is an effective method by comparing the results of the field tests.
Aby wykonać dokładny pomiar prędkości obrotowej wiatraka należy przeprowadzić test jego osiągów. Ponieważ istnieje związek pomiędzy częstotliwością zmian ciśnienia na końcówce wirnika i prędkością obracania wirnika, w niniejszym artykule zaproponowano nową metodę pomiaru prędkości obrotowej końcówki wirnika poprzez badanie pomiaru prędkości obrotowej wentylatora przeciwbieżnego. Przedstawiono również zastosowanie czujników ciśnienia, kart rejestracji danych oraz technologii programistycznych do pomiaru prędkości wskazań zawartych w poprzednich systemach automatycznego testowania osiągów wentylatora. Porównanie wyników prób terenowych dowodzi skuteczności tej metody.
Źródło:: AGH Journal of Mining and Geoengineering; 2012, 36, 3; 209-215
1732-6702
Pojawia się w:: AGH Journal of Mining and Geoengineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Analysis of residual strength of a helicopter tail boom
Autorzy:: Reymer, P.
Leski, A.
Powiązania:: https://bibliotekanauki.pl/articles/246055.pdf
Data publikacji:: 2010
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: residual strength
tail boom
crack tip opening angle
Opis:: The aim of this work is to determine the residual strength of a Mi-24 helicopter's tail boom with a structural damage. The idea of this work has come from the fact that these helicopters are operated on a battlefleld and often suffer such damages. It may be crucial to make a quick estimation whether any particular damage can cause a critical failure to the whole structure. The scope of this work covers static loading of the structure during landing. The analysis has been based on a numerical model that makes use of the Finite Element Method. The model has been developed using reverse engineering techniques. Structural discontinuities have been modelled in characteristic sections where stress concentrations occur. Boundary conditions and loads applied have been chosen to simulate normal and hard landings. Two failure criteria have been chosen: one based on the Crack Tip Opening Angle (CTOA) method that enables very efficient verification, and the second concerning the tail boom tip dislocation, taken from the helicopter,s alignment manual. The specific load history has been designed to enable detection of tail boom tip dislocation due to plastic strain in the vicinity of damage tips after the hard landing.
Źródło:: Journal of KONES; 2010, 17, 1; 343-349
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Rotor blade vibration simulator of steam turbine with aliasing frequencies up to 25 Hz
Autorzy:: Piechowski, L.
Rządkowski, R.
Troka, P.
Piechowski, P.
Szczepanik, R.
Powiązania:: https://bibliotekanauki.pl/articles/175409.pdf
Data publikacji:: 2016
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: tip-timing
rotor blade vibration
blade vibration simulator
Opis:: The tip-timing measurement of rotor blade vibration of a real turbine is very expensive. An electronic simulator of unshrouded steam turbine rotor blade vibrations for aliasing frequencies up to 25 Hz is presented in this paper. The results of the simulated blade vibrations were compared with ones carried out on a real steam turbine. The simulator can be also used to: calibrate the measurement channels, help in the designing and manufacturing new tip-timing systems, and check the reliability of other tip-timing systems.
Źródło:: Transactions of the Institute of Fluid-Flow Machinery; 2016, 134; 121-129
0079-3205
Pojawia się w:: Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Effect of circumferential grooves casing treatment on tip leakage flow and loss in a transonic mixed-flow compressor
Autorzy:: Qiang, X. Q.
Zhu, M. M.
Teng, J. F.
Powiązania:: https://bibliotekanauki.pl/articles/279263.pdf
Data publikacji:: 2013
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: compressor
casing treatment
tip leakage
flow loss
numerical simulation
Opis:: A numerical simulation of a single stage transonic mixed-flow compressor is presented. The simulation is run with a multi-passage grid that models the 3D, viscous, steady and unsteady flow field. The effect of circumferential grooves casing treatment on the compressor overall performance, tip leakage flow and loss has been studied. The results show that the narrow operating range has been significantly broaden by the casing treatment grooves, while the mismatching between the rotor and stator still exists and becomes even worse. Detailed analysis indicates that the fluid from circumferential grooves is injected into the blade passage near the suction surface and re-energizes the leakage flow, which makes mainly contribution to manipulation of the tip leakage flow and stall margin improvement. Since the pressure difference across the blade tip section has a great impact on the effectiveness of circumferential grooves, the positions of shock wave and tip leakage flow as well as where the interaction takes place ought to be taken into account through the casing treatment design procedure.
Źródło:: Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 903-913
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Tip leakage flows in turbines
Autorzy:: Lampart, P.
Powiązania:: https://bibliotekanauki.pl/articles/1955214.pdf
Data publikacji:: 2006
Wydawca:: Politechnika Gdańska
Tematy:: axial flow turbine
shrouded/unshrouded blades
tip leakage
CFD
Opis:: Mechanisms of formation of the tir leakage over shrouded and unshrouded rotor blades are described in the paper. The loss diagrams for these two types of leakage in a wide range of cascade inlet and outlet flow angles are also plotted. They are obtained in a theoretical way from a model of stream mixing with the help of simplifying assumptions concerning the load of the rotor profile. Results of numerical investigations based on a 3D RANS solver FlowER are also presented in the paper. They extend on the effects of geometrical and flow parameters of the cascade (stage or stage group) on the development of flow losses in the leakage-dominated region as well as on the interaction of tip leakage flow with secondary flows. The tip clearance size, the level of flow turning in the cascade, incidence angle and the effect of relative motion of the blades and endwall are considered here in the case of unshrouded free-tip blades. In the case of shrouded rotor blades the tip leakage mass flow rate and its direction on the re-entry to the blade-to-blade passage. Since the tip leakage non-uniformities are hardly dissipated within the blade row where they originate, the interaction of the tip leakage with the flow in the downstream stator is considered. Same investigations also take into account the effect of relative motion of the stator and rotor blades.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 139-175
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 16.

Tytuł:: Numerical analysis of the tip vortex in an air-conditioners propeller fan
Autorzy:: Wang, J.
Wu, K.
Powiązania:: https://bibliotekanauki.pl/articles/1955218.pdf
Data publikacji:: 2006
Wydawca:: Politechnika Gdańska
Tematy:: tip vortex
internal flow field
propeller fan
numerical simulation
Opis:: A steady, incompressible, turbulent flow field inside a propeller fan used in an air conditioner has been analyzed numerically using the single-equation Spalart-Allmaras turbulence model. It has been found that the formation of tip vortex starts from the blade tip's suction side at about one third of the axial chord's length aft of the rotor's leading edge. It is due to the rolling-up of the intense shear layer flow between the main axial flow and the suck-in inward flow caused by the large pressure difference between the pressure and the suction sides. The tip vortex passes through the blade passage in a curve reversed towards the direction of the blade's rotation. Its trace is partial to the tangential direction as it goes into the aft part of the blade passage covered by the shroud and, simultaneously, its trace in the radial direction is turned from the outward direction to the inward direction. The operating flow rates have an important effect on the axial position of the tip vor-tex's trace, while its effect on the radial position is negligible. At law flow rates, the vortex disappears at a location closer to the leading edge. The effect of the shroud's width on the tip vortex's trajectory is notable. For a fan with a wide shroud, the trace of the tip vortex moves upstream with a smaller radial influence region than that of a fan with a narrower shroud.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 101-112
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 17.

Tytuł:: Microstructural study of failure phenomena in WC 94%-Co 6% hard metal alloy tips of radial picks
Autorzy:: Nahak, S.
Chattopadhyaya, S.
Dewangan, S.
Hloch, S.
Krolczyk, G.
Legutko, S.
Powiązania:: https://bibliotekanauki.pl/articles/102813.pdf
Data publikacji:: 2017
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:: radial picks
WC-Co tip
FESEM
EDS
failure behaviour
Opis:: An excellent combination of hardness, strength, stiffness and high melting point has proved the WC-Co as an ideal material for tools that are used for metal cutting, coal mining, oil drilling, etc. The ongoing research in WC-Co is focussed on enhancing its wear resistant properties as much as possible. For the purpose, many attempts have been made to study the tribological behaviour of WC-Co for a long time. Researchers have used various grades of WC-Co in different working environments and accordingly they have characterized the wear phenomena involved there within. In this direction of research, the present paper makes an attempt to understand various wear behaviours in WC 94%-Co 6% hard metal alloy. WC-Co was used as a tip of the coal cutting tool named radial pick. Two radial picks have been taken for critical analysis through field emission scanning electron microscopy (FESEM) attached with energy dispersive X-ray spectroscopy (EDS). In this work, the failure behaviours in the tools have been divided into five categories: (1) Abrasion on individual grain; (2) Corrosion in carbide grains; (3) Fragmentation and removal of WC grains; (4) Pores in WC grains; and (5) Coal and rock embedding. The most possible reasons behind each failure phenomenon have been explained comprehensively with the help of high-resolution microscopic images. However, it is usually observed that, initially, the tool gets minor cracks due to sudden impact. These cracks provide a path to the rock and coal particles to get entrenched inside the microstructure of cemented carbide. Finally, the intermixed external elements degrade the binder content (i.e. cobalt) and the tool becomes useless.
Źródło:: Advances in Science and Technology. Research Journal; 2017, 11, 1; 36-47
2299-8624
Pojawia się w:: Advances in Science and Technology. Research Journal
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 18.

Tytuł:: Numerical analysis on the influence of the twisted blade on the aerodynamic performance of turbine
Autorzy:: Jin, J.
Wang, Z.
Cao, L.
Powiązania:: https://bibliotekanauki.pl/articles/258444.pdf
Data publikacji:: 2016
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: turbine
twisted blade
leakage vortex
pressure gradient
tip clearance
Opis:: With the gradual increase of the thermal power unit capacity, the inlet steam parameters and flow of the turbine also increase gradually, which causes considerable secondary flow loss. Therefore, studying the causes and distribution of secondary flow loss within the level is of great significance to effectively improve the stage internal efficiency of turbine. Take high-pressure stage moving blade of a turbine as the research object, and adopt the k-ωSST model, the SIMPLEC algorithm to numerically simulate the formation and development process of leakage vortex between the tip clearance of the positive bending twisted blade and its effect on the secondary flow of cascade passage. Results show that relative to the conventional twisted blade, the scope of influence of leakage vortex which the steam flow formed near the suction surface of positive bending twisted blade and the disturbance to passage mainstream become smaller, and the increase of tip clearance has weakened the „C” type pressure gradient of suction surface of the positive bending twisted blade, increased the thickness of the boundary layer at both ends of blades and the loss of the blade end.
Źródło:: Polish Maritime Research; 2016, S 1; 86-90
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 19.

Tytuł:: Importance of explant size and origin for cryopreservation of Rosa pomifera “Karpatia” shoot tips by a droplet vitrification method
Autorzy:: Kwasniewska, E.
Dziedzic, E.
Pawlowska, B.
Powiązania:: https://bibliotekanauki.pl/articles/951284.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: cryopreservation
Rosa pomifera
shoot tip
droplet vitrification
axenic culture
Źródło:: BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796
Pojawia się w:: BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 20.

Tytuł:: Experimental Study on the Half Flat Tip Serrated Trailing Edge for Stand Fan
Autorzy:: Lee, Hsiao Mun
Lim, Kian Meng
Xie, Jinlong
Lee, Heow Pueh
Powiązania:: https://bibliotekanauki.pl/articles/177337.pdf
Data publikacji:: 2020
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:: trailing edge noise
half flat tip
serration
stand fan
Opis:: The effectiveness of half flat tip serrations on reducing fan blade trailing edge noise was investigated using experimental methods. The experiments were conducted at an anechoic chamber under different rotating fan speeds. Numerical simulations were performed to investigate the mass flow rate generated by the serrated fan and compared with that by the baseline fan. The experimental results showed that the overall amount of noise reduction decreased with the increasing of the distance away from the fan. It was found that the effectiveness of the serrations was not proportional with the rotating speed of the fan where it was most effective at 263 rpm and 2041 rpm with noise reductions about 3.1 dBA and 3.5 dBA, respectively. This phenomenon might be depended on how trailing edge vortex would interact with the serrations at different speeds of the fan. The reduction of mass flow rate reduced with the increasing of the rotating speed and the highest reduction was found at 263 rpm which was about 18% and this reduction was accompanied by overall noise reduction of 3.1 dBA.
Źródło:: Archives of Acoustics; 2020, 45, 2; 359-365
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 21.

Tytuł:: Probe radius correction methods - review and comparison of existing methods
Autorzy:: Rak, A.
Woźniak, A.
Powiązania:: https://bibliotekanauki.pl/articles/385250.pdf
Data publikacji:: 2009
Wydawca:: Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:: coordinate measuring machine (CMM)
scanning probe
probe tip radius correction
Opis:: Scanning technology has been becoming more common then ever. Scanning offers new and effective possibilities of measurement. Nowadays planning, production and assembling without high accurate metrology is impossible. Measurement of small, curved elements became much easier with great development of mechanical components of measure machines, such as: guideways, transducers, bearings, servomechanisms. All this improvement made possible to collect with good accuracy points in high density. Algorithms, and computer software were greatly improved as well. Especially, many efforts were put on probe radius correction algorithms development. In this paper a review and a comparison of probe radius correction methods are shown.
Źródło:: Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 169-171
1897-8649
2080-2145
Pojawia się w:: Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 22.

Tytuł:: Multiple spike stall cells in low speed axial compressor rotor blade row
Autorzy:: Taghavi-Zenouz, R
Abbasi, S.
Powiązania:: https://bibliotekanauki.pl/articles/279770.pdf
Data publikacji:: 2015
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: axial compressor
spike stall inception
tip leakage flow
frequency spectrum
Opis:: Inception and development of multiple stall cells of short length scales are numerically investigated in an axial compressor rotor blade row. The method of investigation is based on time accurate three-dimensional full annulus simulations. Time dependent flow structure results revealed that there are two criteria responsible for inception of a special kind of stall, introduced as spike stall in the literature. These criteria are defined as leading edge spillage and trailing edge backflow, which occur at specific mass flow rates near to stall conditions. The numerical results revealed that once the spike stall cells appear, they cover roughly two blade passages in the circumferential direction and cover about 25% of the blade height. By further revolution of the blade row, the number of cells tends to increase. For the present case study, the number of stall cells increased to three after 8.5 rotor revolutions from the moment of the initial spike stall occurrence. Even at this moment, both of the above mentioned criteria for the spike stall inception have been observed within the blades passages. These events caused the inlet relative flow angle to the blade rows, and therefore the flow incidence angle and consequent blockage to the main flow, to increase. The tip leakage flow frequency spectrum has been studied through surveying instantaneous static pressure signals imposed on pressure side of the blades and also on the casing walls. These latter results showed that any further revolving of the rotor blade row, exceeding 8.5 revolutions, causes the spike stall to disturb the flow structure significantly.
Źródło:: Journal of Theoretical and Applied Mechanics; 2015, 53, 1; 47-57
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 23.

Tytuł:: Research on Changes in Microstructures and Mechanical Properties of Welding Caps as a Result of their Usage During Resistance Spot Welding Process
Autorzy:: Rdzawski, Zbigniew
Kwaśniewski, Paweł
Głuchowski, Wojciech
Łagoda, Marek
Maleta, Marcin
Boczkal, Sonia
Franczak, Krystian
Powiązania:: https://bibliotekanauki.pl/articles/2203749.pdf
Data publikacji:: 2023
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: CuCrZr alloy
resistance spot welding
mechanical properties
microanalysis
tip electrodes
Opis:: Mating electrodes made of copper alloys are commonly used for welding galvanized steel sheets used in the production of car bodies. These alloys are characterized by high mechanical properties, a high level of electrical and thermal conductivity as well as the stability of these properties under changing conditions of current, thermal and mechanical load. Much careful attention was paid to the essence of the ongoing structural changes as well as to the mechanical properties in the welding process (RSW - Resistant Spot Welding) of steel sheets, including high-strength ones. There is a lack of research on structural changes and the related mechanical properties occurring in welding electrodes made of copper alloys caused by the welding process. This study is devoted to these issues and contains a critical review of the research results enabling a better understanding of the relationships between the structure and properties of welding electrodes caused by the cyclic welding process. In order to illustrate the phenomena occurring during the welding process, both in the material to be welded and in the tip electrodes, hardness and structural tests were carried out on electrode samples before and after their exploitation. The data collected in the article supplements a certain lack of information in the literature regarding the microstructural aspects of the welding process of galvanized steel sheets for the production of car bodies. The conducted research may be the starting point for the search for more effective materials for the tip electrodes.
Źródło:: Archives of Metallurgy and Materials; 2023, 68, 1; 295--306
1733-3490
Pojawia się w:: Archives of Metallurgy and Materials
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 24.

Tytuł:: Effects of boundary layer control method on hydrodynamic characteristics and tip vortex creation of a hydrofoil
Autorzy:: Ghadimi, P.
Araz-Tanha, A.
Nemati-Kourabbasloo, N.
Tavakoli, S.
Powiązania:: https://bibliotekanauki.pl/articles/259965.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:: steady water injection
boundary layer control
hydrofoil
NACA 0015
tip vortex
Opis:: There is currently a significant focus on using boundary layer control (BLC) approach for controlling the flow around bodies, especially the foil sections. In marine engineering this is done with the hope of increasing the lift – to – drag ratio and efficiency of the hydrofoils. In this paper, effects of the method on hydrodynamic characteristics and tip vortex formation of a hydrofoil are studied. Steady water injection at the tip of the hydrofoil is simulated in different conditions by using ANSYS-CFX commercial software. Validity of the proposed simulations is verified by comparing the obtained results against available experimental data. Effects of the injection on the lift, drag, and lift – to – drag ratio are studied and the ranges within which the injection has the most positive or negative effects, are determined. Furthermore, flow pattern and pressure variation are studied upon the water injection to determine the most positive and negative case and to ascertain the main reasons triggering these phenomena.
Źródło:: Polish Maritime Research; 2017, 2; 27-39
1233-2585
Pojawia się w:: Polish Maritime Research
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 25.

Tytuł:: A simple model of the scanning near-field optical microscopy probe tip for electric field enhancement
Autorzy:: Wang, Y.
Cai, W.
Yang, M.
Liu, Z.
Shang, G.
Powiązania:: https://bibliotekanauki.pl/articles/174091.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: near-field tip
electromagnetic field enhancement
finite-difference time-domain
FDTD
Opis:: In this paper, we present a simple near-field probe model that is composed of an elongated ellipsoid and a finite metal truncated cone. The elongated ellipsoid has been shown to act as a protrusion or separate particle near a truncated cone apex with strong near-field enhancement under laser excitation. By controllably varying the length of the ellipsoid protrusion from the truncated cone, the truncated cone-ellipsoid probes can be adapted to the suitability of near-field probes. The effects of substrate material and excitation wavelength on the near field enhancement for different tip apexes are also discussed. In addition, we compared the properties of the truncated cone-ellipsoid probe with the widely used hemisphere conical tip by launching surface plasmon polaritons on plasmonic waveguides to prove the suitability of the truncated cone-ellipsoid probes as high performance near-field probes. The present simple model would provide a theoretical basis for the actual construction of probes.
Źródło:: Optica Applicata; 2017, 47, 1; 119-130
0078-5466
1899-7015
Pojawia się w:: Optica Applicata
Dostawca treści:: Biblioteka Nauki

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