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1

Analysis of measurement methods for fuel injection spray parameters from marine engine injector

Lewińska J.

Journal of KONES

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2016

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Vol. 23, No. 4

275--282

EN

One of the main factors influencing on the optimal combustion process in a marine diesel engine’s cylinder is the fuel injection spray and the fuel atomization. The complexity of mentioned phenomena in the marine diesel engine’s cylinder may cause difficulties in their analysis. Measurement methods, allowing obtaining information about the process of fuel injection and evaporation in the diesel engine’s cylinder are qualified as optical visualization methods. It provides non-invasive measurement of parameters of fuel injection spray. The article presents the analysis of various aspects of optical measurement methods application that allow specifying parameters of fuel injection spray in the diesel engine’s cylinder. Initial studies were carried out using Mie scattering method. In addition, visualization obtained by shadowgraphy method was presented also. The constant volume chamber was used as a working area. The conventional light source was used in case of Mie scattering and a laser light source in shadowgraphy. For the lighting test was used a double-pulse Nd:YAG laser. The wavelength laser 532 nm was used. A course of the injection process was recorded by high-speed camera. The Mie scattering method allows analysing the fuel injection phenomena in macro scale. Specified geometric parameters. The shadowgraphy method allows to asses parameters of diesel fuel injection from marine diesel engine’s injector in the micro scale.

2

Laser based diagnostic system for spray measurements

Kapusta Ł. J., Jaworski P., Teodorczyk A., Kowalski J.

Journal of KONES

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2015

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Vol. 22, No. 3

91--98

EN

The paper discusses the capabilities of the laser diagnostic system for dispersed multiphase flows measurements, which was recently commissioned at the Institute of Heat Engineering (ITC) at Warsaw University of Technology. The system presented in the paper is multifunctional and is capable to use different measurements techniques such as shadowgraphy, Mie scattering (scattering on the gas-liquid interface) and LIF (laser induced fluorescence). It provides possibility of switching from one technique to another depending on the characteristics of the observed combustion/injection mixing process. The operational features are discussed in-detail. The study presents the required and possible system setups. Special attention was focused on the system components, which are needed for relevant measurement techniques. Moreover, the limitations of the measurement techniques are discussed and the example measurements are presented. The study shows that using different techniques extends the measurement capabilities of the system with minimum investment costs. This results from the fact that certain system components for different techniques are the same. Moreover, one can conclude that the system design allows certain measurement methods to be applied simultaneously, which results in synergy by making possible drawing more advanced conclusions on observed phenomena

3

Dynamic fragmentation of laser shock-melted metals: some experimental advances

Resseguier T. de, Loison D., Lescoute E., Signor L., Dragon A.

Journal of Theoretical and Applied Mechanics

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2010

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Vol. 48 nr 4

957-972

EN

While spall damage in solid materials has been one of the most widely studied shock-driven phenomena, very little data can be found yet about spallation in liquid metals. In recent papers, some of present authors have reported on exploratory investigations of liquid spall – sometimes called "microspall" – in tin samples melted upon laser shocks of high intensities. Modelling approaches have also been discussed and compared with experimental observations. In particular, theoretical fragment size distributions have been compared with experimental distributions inferred from image analyses on fragment-impacted recovery polymer shields. While the curves representing the number per unit area vs. size of fragments present a similar aspect, the numbers predicted by an energy-based model are significantly greater than those observed experimentally. This is due predominantly to the characterisation technique, limited to surface examination, while a number of fragments penetrate the polymer shield and lay below its surface. This is why a new fragment recovery technique is being tested in this paper. This technique, based on a highly transparent low density gel, allows soft recovery and easier observation (compared e.g. with foams or aerogels) of the fragments size, shape and penetration depth, with improved spatial resolution. Coupled with shadowgraphy, scanning electron micrography and optical micrography, this recovery technique progress allows for an advanced insight into the henomenology of microspall related fragmentation. To show it, laser shocks upon a tin target and an aluminium target are investigated, leading to different scenarios regarding melting conditions and fragmentation processes.

PL

O ile problem łuszczenia i wykruszania się materiałów pod wpływem obciążeń udarowych został bardzo szeroko przeanalizowany, bardzo niewiele informacji spotyka się odnośnie odpryskiwania metali w stanie płynnym. Niektórzy z autorów obecnej pracy przeprowadzili badania nad odpryskiem płynnym, czasem zwanego mikroodpryskiem, polegającym na dezintegracji materiału stopionego impulsami laserowymi o dużej mocy. Zaproponowali oni także sposób modelowania tego zjawiska, weryfikując go z wynikami eksperymentalnymi. W szczególności, rozkłady teoretyczne rozmiaru odprysku porównano z wynikami doświadczeń, gdzie metodami analizy obrazu zmierzono rozmiar odpryśniętych cząstek uwięzionych w specjalnych ekranach polimerowych umieszczonych za próbką. Zauważono, że analityczne krzywe rozkładu reprezentujące liczbę odłamków na jednostkę powierzchni w funkcji wielkości tych odłamków pozostają w zgodzie z eksperymentem, jednak już sama ilość zdefragmentowanego materiału wynikającego z modelu energetycznego znacznie przewyższa rezultat doświadczalny. Ta nadwyżka wynika głównie ze stosowanej metody zliczania ilości odprysku, ograniczającej się jedynie do badań powierzchniowych, tymczasem część odprysku penetruje ekran polimerowy znacznie głębiej. Z tego powodu w niniejszej pracy zaproponowano i przetestowano nową metodę jakościowego i ilościowego określania odprysku oraz przedyskutowano jej skuteczność. Nowa metoda bazuje na zastosowaniu zamiast ekranów polimerowych przezroczystego żelu o małej gęstości, umożliwiającego łatwą obserwację (w porównaniu do pianek i aerożeli) wielkości odpryskiwanych cząstek, ich kształtu oraz głębokości penetracji przy zwiększonej rozdzielczości przestrzennej obrazu. Technika ta, wspomagana cieniografią oraz mikrografią optyczną i elektronową (mikroskop skaningowy), stanowi zaawansowane narzędzie do badań nad zjawiskiem mikroodprysku. Do prezentacji skuteczności tej metody przeprowadzono doświadczenia nad próbkami z cyny i aluminium przy różnych warunkach topienia i defragmentacji pod wpływem impulsu laserowego.

4

A method for the determination of spatial electron density distribution in great Plasma-Focus devices

Kasperczuk A., Paduch M., Pisarczyk T., Tomaszewski K.

Nukleonika

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2002

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Vol. 47, nr 1

23-26

EN

Determination of the electron density of plasma generated in a great plasma-focus device by means of interferometry is very difficult or sometimes impossible. In order to determine spatial electron density distributions of plasma in a PF-1000 device, a special method was prepared, with the use of plasma images obtained by means of both an optical frame camera and shadowgraphy. Analysis of plasma radiation in the very narrow Äë = 60 Ĺ optical range allowed us to determine the relation between intensity of the plasma radiation and the electron density. It was also shown that the influence of electron temperature on plasma radiation is not large. The presented method allowed us to obtain spatial electron density distributions of plasma (in relative units) in the PF-1000 device. By means of this method a number of important information about the plasma-focus phenomenon was obtained.