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1
Content available Quantitative visualisation of compressible flows
Stryczniewicz W.
Prace Instytutu Lotnictwa
|
2018
|
Nr 1 (250)
132--141
EN
The paper demonstrates the feasibility of quantitative flow visualisation methods for investigation of transonic and supersonic flows. Two methods and their application for retrieving compressible flow field properties has been described: Background Oriented Schlieren (BOS) and Particle Image Velocimetry (PIV). Recently introduced BOS technique extends the capabilities of classical Schlieren technique by use of digital image processing and allow to measure density gradients field. In the presented paper a review of applications of BOS technique has been presented. The PIV is well established technique for whole field velocity measurements. This paper presents application of PIV for determination of the shock wave position above airfoil in transonic flow regime. The study showed that application of quantitative flow visualisation techniques allows to gain new insights on the complex phenomenon of supersonic and transonic flow over airfoils like shock-boundary layer interaction and shock induced flow separation.
PL
Artykuł przedstawia możliwości zastosowania jakościowych metod wizualizacji przepływu do badań przepływów ściśliwych. Przedstawiono dwie metody umożliwiające pomiar parametrów pola przepływającego płynu: anemometrię obrazową oraz technikę fotografii smugowej opartej na obrazowaniu tła. Ostatnio opracowana nowa metodyka pozwala na rozwinięcie klasycznej techniki Schlierena, dzięki wykorzystaniu cyfrowej analizy obrazu umożliwia jakościowy pomiar gradientów gęstości. W publikacji przedstawiono przegląd zastosowań techniki fotografii smugowej wykorzystującego obrazowanie tła do jakościowego pomiaru zmian gęstości przepływów ściśliwych. Anemometrii obrazowa jest techniką wizualizacyjną, umożliwiającą bezinwazyjny pomiar pola prędkości przepływającego płynu. W publikacji przedstawiono zastosowanie anemometrii obrazowej do wyznaczenia pozycji fali uderzeniowej ponad powierzchnią profilu dla okołodzwiękowych prędkości przepływu. Przedstawione wyniki wykazały, iż zastosowanie technik jakościowej wizualizacji przepływu umożliwia pogłębienie analizy badanych zjawisk w warunkach przepływu okołodźwiękowego i naddźwiękowego, takich jak oddziaływanie fali uderzeniowej z warstwą przyścienną oraz oderwania przepływu spowodowanego falą uderzeniową.
2
Content available Water tunnel visualisation and numerical analysis of flow around TS-11 Iskra wing with flow control surfaces
Szczepaniak R., Walusiak S., Bąbel R., Mazurek Ł, Stryczniewicz W., Kowaleczko G.
Journal of KONES
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2017
|
Vol. 24, No. 2
253--261
EN
The article presents investigation of flow around wing of TS-11 Iskra airplane. The flow visualization around 3D printed model of wing with flow control surfaces was performed in a water tunnel. Two configurations were investigated: first with a flap and second with an aileron. The flow visualisation was performed with a use of a dye. The geometry of model was prepared with use Computer Aided Design (CAD) software basing on scans of real object and technical documentation. The model was built with use of additive manufacturing technology. Movement of the flow control surfaces was remotely controlled with servomechanisms incorporated in channels inside the model. In order to perform qualitative validation of the results the investigated flow was simulated with use of CFD commercial software. The article presents visualisation results of flow around wing section of TS-11 Iskra airplane and water tunnel model preparation. In order to perform qualitative validation of the results the investigated flow was simulated with use of CFD commercial software. The goal of the research was to investigate the complex flow field in the vicinity of flow control surfaces and provide aerodynamic characteristics at various deployment angles via numerical simulations. The results can be used for verification of water tunnel testing procedures and training.
3
Koncepcja badań wizualizacji przepływu cieczy newtonowskich i nienewtonwoskich
Zgolak P.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2013
|
z. 102
191-194
EN
Research aims at carry out flows of Newtonian and non-Newtonian fluids. It can be using device models and methods of flow visualization computer processing of flow images. Preparation of the measuring stand to carry out research visualization.
4
Content available Eksperymentalne pomiary geometrii kawitującego jądra wiru oraz pola prędkości w jego otoczeniu
Suchecki W., Alabrudziński S.
Inżynieria i Aparatura Chemiczna
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2013
|
Nr 6
563--565
PL
W pracy przedstawiono eksperymentalną metodę pomiaru kawitującego jądra wiru generowanego przez model płata przy dużych prędkościach względnych. Przeprowadzone badania eksperymentalne polegały na rejestracji fotograficznej geometrii wiru generowanego przez model płata w tunelu kawitacyjnym oraz na pomiarach pola prędkości przepływu w sąsiedztwie kawitującego jądra wirowego metodą DPIV. Układ pomiarowy obejmował laser New Wave 120XT-15Hz, dual-Nd:YAG oraz kamerę pco.l200hs z synchronizerem ILA. Zastosowana w pracy tzw. maska kalibracji, pozwoliła na usunięcie zniekształceń obrazu, jednak nie pozwoliła na jednoznaczne określenie położenia obszaru pomiarowego względem ścian kanału. Stwierdzono przydatność zastosowanych metod wizualizacyjnych do badania przepływów, w których występuje kawitacja.
EN
The paper presents the experimental method for measurements of cavitating tip vortex generated by the hydrofoil model at high relative velocities. The experimental procedure included the image acquisition of cavitating tip vortex geometry and DPIV measurements of surrounding liquid velocity field. The measuring system included the New Wave 120XT-15Hz laser, dual- Nd: YAG laser and the camera pco,1200hs with Synchronizer ILA. The socalled calibration mask used during experiments made it possible to remove the image distortion, however, did not allow for the clear identification of the measurement area position with respect to canal walls. The usefulness of applied methods in the study of flow visualization in the presence of cavitation was demonstrated.
5
Content available remote Visualisation of Granular Material Concentration Changes, During Silo Discharging Process, Using ECT Large Scale Sensor
Grudzień K., Chaniecki Z., Matusiak B., Romanowski A., Rybak G., Sankowski D.
Image Processing & Communications
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2012
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Vol. 17, no. 4
327--338
EN
Measuring changes of bulk materials concentration during gravitational flow, a silo emptying is essential information for the assessment of the behaviour and condition of the material during the emptying of the silo. Parameters obtained during this process are important both in terms of process economics and safety, are the basis for monitoring and diagnostics of the process. Affect the current process, but primarily are the result of their filling the silo, and the process of storing the material. Previous studies, conducted by a team of authors, the laboratory-scale silos and numerical calculations and simulations of its increase, helped build the ECT sensor on a large scale. Results related to the change of scale of the sensor and the actual measurements will be discussed in the article. Proposed by the authors of the paper, the method of visualization, performed in the measuring process, helps to ask about the process and suggests a methodology for dealing with the material stored in the silo.
6
Content available remote Pneumatic actuators with "bouncing" air-jet - part 2: Flow field in the cascade
Tesar V., Peszyński K.
International Journal of Applied Mechanics and Engineering
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2010
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Vol. 15, no 3
867-874
EN
Unusual actuators generating a fluid force action on a small body by issuing an air jet "reflecting" or "bounding back" from an impact on a wall were described in previous publication (Tesar and Peszynski, 2010). The seemingly impossible return from the wall is based on the unusual effect of the wall provided with perforations that allow a part of the jet to pass through. Upon the impingement, the jet is split in two parts, both having to change their directions. It is the part that remains above the wall, the "reflected" jet, that is of interest for the actuation. In particular, the phenomenon was used in shuttle-less loom to prevent the inserted weft from contact with the reed. The details of the flowfield inside the reed - or cascade of foils with passages between them play a critical role in the phenomenon. This was investigated by flow visualisation discussed in the second part of the paper.
7
Content available remote Pneumatic actuators with "bouncing" air-jet - part 1: Numerical solutions
Tesar V., Peszyński K.
International Journal of Applied Mechanics and Engineering
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2010
|
Vol. 15, no 3
855-865
EN
An actuator generating a force action on a small body by an issuing air jet is based on the unusual, little known and seemingly impossible mechanism of the jet "reflecting" or "bouncing back" from an impact on a solid wall. Under usual conditions the bouncing back from the wall is not possible - the trick is the wall is provided with perforations that allow a part of the jet to pass through. On doing so it has to change its direction and this has to be compensated by the remaining part changing its direction too, into the opposite side as seen from the jet axis. This part forms the "reflected" jet. The phenomenon is investigated by flow visualisation and detailed flowfield computations presented in this paper - the first part of which discusses the computed results.
8
Application of the pressure sensitive paint method for transonic flow measurements
Szumski J. A., Doerffer P.
Turbulence : international journal
|
2005
|
Vol. 11
55-63
EN
Traditional measurements of the pressure distribution are conducted with use of pressure taps. Those pressure taps require model surface to be drilled through. In case of such intrusive pressure measurements the instrumentation and model mounting become a problem, especially in case of rotating compressor or turbine blades. The new optical method based on pressure (oxygen concentration) sensitive paints allow to obtain a continuous pressure distribution on the model surface in essentially non-intrusive way. The PSP technology helps understanding of the flow around the model and provides quantitative flow data for further processing. PSP method treated in this paper proved to be a very good solution for complex flows. The scope of this paper is to present the basics of the PSP method. It covers only the basic equations, general idea of the method, typical system set up and some of the approaches to PSP paint application. Typical PSP system is explained as well as the formulation of the PSP paint. The physical phenomena of the excitation, emission and oxygen quenching is explained. Deployment of the system at IFFM PAS is in the final stage, and preliminary calibration results are available. At the end of this paper the IFFM PAS plans for future, current PSP development challenges, actions to be taken, and some of the expected results are discussed.
9
Content available remote Experimental investigation of the convective heat transfer around a perpendicular plate by means of flow visualization techniques
Błaszczuk A., Mirek P.
Archives of Thermodynamics
|
2004
|
Vol. 25, no. 3
73-86
EN
The subject of the study is presentation of optical techniques for the measurement of local values of overall heat transfer coefficient. Measuring systems based on Schlieren and interference systems, built either in classical versions or modified by the authors of the present study, were used in the research. The recording of the distribution of optical density of the information carrier around the object under analysis was carried out using a CCD matrix with the image acquisition card. The role of the information carrier in the experimental research was performed, alternatively, by the collimated beam of a 25 mW-power He-Ne laser or a slotted white light source in the form of a halogen lamp, type H3. The modifications introduced to the optical measuring range along with a reduction in the susceptibility of the systems to misalignment.
10
Metoda korekty wykresów pól prędkości w cyfrowej anemometrii obrazowej
Suchecki W., Alabrudziński S.
Inżynieria i Aparatura Chemiczna
|
2003
|
Nr 3
14-20
PL
Zrealizowana praca miała na celu opracowanie i opanowanie metody korekty wykresów pól prędkości otrzymanych dzięki cyfrowej anemometrii obrazowej. Opracowano algorytm mający na celu identyfikację wektorów błędnych oraz zastąpienie ich wektorami uśrednionymi. Na podstawie algorytmu napisano program komputerowy (dla systemu Linux) oraz przeprowadzono szereg obliczeń celem weryfikacji. Uzyskane wyniki pozwoliły stwierdzić przydatność zastosowanych metod oraz dostarczyły wiele istotnych i cennych informacji mogących znacznie udoskonalić metodę dla przepływów ustalonych i quasi-ustalonych
EN
The aim of this work was to elaborate and acquire proficiency in the correction method of velocity fields diagrams obtained by digital image anemometry. The algorithm for false vectors identification and their replacement by average vectors was determined. On the basis of this algorithm the software (for the Linux system) was written and a number of verifying calculations were carried out. The results obtained enabled one to confirm usability of the method. They were also a source of valuable information how to improve the method for steady state and quasi—steady state flows.
11
Content available remote Instability of the interface between fluids of different densities flowing through a complex vertical hydraulic system
Grygoriev A., Jeżowiecka-Kabsch K., Szewczyk H.
International Journal of Applied Mechanics and Engineering
|
2003
|
Vol. 8, no 3
403-411
EN
The impact of the gas density difference on formation of flow patterns of fluids of different density was analysed. Physical modelling of a non-isothermal laminar flow of a gas mixture in a vertical epitaxial reactor chamber was carried out and the model flow was visualised. Visualisation studies, performed using a smoke method, confirmed that the stability of a gas interface determines the flow pattern in the chamber. The Rayleigh-Taylor instability occurs in the flow through a reactor, which, together with the Kelvin-Helmholtz instability and with the superposition of convection flows on the principal flow, shapes the flow pattern in the whole reactor chamber. On the basis of results of visualisation studies, the possibility of making the flow through a vertical reactor stable was indicated if the inlet guide apparatus is applied and the flow direction is reversed.
12
On some implications of the network arrangement of pore channels
Cieślicki K., Lasowska A.
Bulletin of the Polish Academy of Sciences. Earth Sciences
|
1999
|
Vol. 47, nr 2-3
103-111
EN
This work presents a certain network model of porous medium. The model consists of capillaries, with the range of sizes distributed randomly in 2D regular networks of constant topological structures. The variety of the tube radii models the variety of dimensions, shapes and tortuousity of real pore channels. The influence of pore size distribution and the value of coordination number of network nodes on overall resistance to flow have been considered. Special attention has been paid to the possibility of appearance in a strongly non-homogeneous network of preferential flow paths. It was also demonstrated that in the case of homogeneous network even small disturbance propagates far away to its surroundings. The observation of expanding disturbance was qualitatively confirmed by detection of flow pattern in a porous medium composed of identical spheres in cubic arrangement. CECC
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