This article presents the results of investigations focused on the role of molecularly ordered structures (molecular clusters) on combustion process. The proposed new mechanism of the reactions initiation takes into account the role of molecular clusters in energy (heat and energy of electrons emitted by the surface of the walls of combustion chamber) conductivity regulation. Literature survey shows that molecular clusters created by aromatic hydrocarbons are responsible for particulate matter. The combustion process itself is not uniform in whole combustion chamber. Such diversity, caused mainly by heterogeneous thermal state of combustion chamber is recognized as significant reason to create various products of combustion including carbon oxides, carbon dioxides and nitrogen oxides. Jet fuel and its blends with n-butanol and biobutanol in concentration from 10 to 75 % (V/V) were subjected to laboratory tests. Such blends were also tested on the test rig with a miniature turbojet engine – MiniJETRig. Engine operating parameters and carbon oxide emission were measured. The relations between electrical conductivity and parameters of engine test (e.g. temperature in selected points in combustion chamber) were assessed. Engine tests were carried out according to specific profile of engine test, which models different engine operating modes. The results of experimental investigations, shown in the article, initially confirm the proposed mechanism of the oxidation reactions initiation during combustion process.
There are currently many studies undergoing in the field of using alternative fuels for supplying different types of propulsion units. The ASTM standard in the aerospace industry, allows using five different technologies of manufacturing synthetic components apart from standard oil-based fuel for the propulsion of turbine engines (as a blend up to 50% with conventional fuel). One of these is a technology associated with the process of converting alcohols (isobutanol) to jet fuel – Alcohol to Jet (ATJ). In the research performance, emission parameters were measured on laboratory test rig with miniature turbojet engine (MiniJETRig). The test rig has been created in Air Force Institute of Technology for research and development works aimed at alternative fuels for aviation. The miniature engine was fuelled with conventional jet fuel – Jet A-1 and blend of Jet A-1 with 2-ethylhexanol. The results for this blend were compared with the results obtained for neat Jet A-1 fuel in terms of different engine operating modes, according to specified methodology. The conducted tests did not show significant differences in engine operating parameters (thrust, fuel consumption and thrust specific fuel consumption) and the values of CO, CO2 and NOx emission indices between the tested fuels. The engine tests took place in similar ambient conditions. Laboratory tests of selected physicochemical properties were also carried out for both fuel samples.
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The result of operating the military helicopters in a dusty environment is a loss of performance and premature failures of gas paths of the engines. The efficient protection of the power plant against dust ingestion is tough, especially in the desert. The article summarises the experience accumulated while operating the military helicopters under harsh conditions in Poland and during foreign missions. There were characterised the types of conducted missions, operated helicopters, protection methods of engines and common failures. It was stated that the performance of TV3-117 engines and their particle separation systems was insufficient in the mountains and on the desert (Iraq and Afghanistan). The deterioration of gas paths resulted in the loss of helicopters’ performance and substantially contributed to the few aircraft incidents. The experience gained during foreign missions is used in training the crews and ground personnel and in the programmes of modernisation and renewal of the helicopter fleet.
PL
Wynikiem użytkowania śmigłowców wojskowych w warunkach zapylenia jest zmniejszenie osiągów i przedwczesne uszkodzenia traktów gazowych silników. Skuteczna ochrona zespołu napędowego przed pyłem jest bardzo trudna, szczególnie w terenie pustynnym. W artykule zebrano doświadczenia z użytkowania śmigłowców wojskowych w trudnych warunkach w kraju i na misjach zagranicznych. Scharakteryzowano rodzaje wykonywanych misji, stosowane typy śmigłowców, metody ochrony silników i typowe uszkodzenia. Stwierdzono, że osiągi stosowanych silników rodziny TV3-117 i ich systemów odpylania były niewystarczające w warunkach górskich i pustynnych (misje w Iraku i Afganistanie). Deterioracja traktów gazowych silników spowodowała zmniejszenie osiągów śmigłowców i istotnie przyczyniła się do kilku incydentów lotniczych. Doświadczenia zdobyte w trakcie misji zagranicznych są wykorzystywane przy szkoleniu załóg i personelu technicznego oraz w programach modernizacji i wymiany floty śmigłowców.
Aviation is one of the fastest growing modes of transport. Due to the growing number of flights, the consumption of aviation fuels (mainly jet fuels) keeps increasing. The combustion process in the aircraft engine results in harmful exhaust emissions having an adverse impact on the environment. Alternative fuels based on bio-components and biofuels are a way of reducing the harmful exhaust emissions. Analyses and measurements performed on real aircraft engines are complex and expensive. For this reason, increasingly more research and development projects have been carried out on small-scale engines. This paper presents investigations into volatile organic compound emissions from jet fuel combustion in a miniature turbojet engine. Based on chromatography tests, the compositions of exhaust gases produced by the jet engine fed with various fuels were determined, which in turn led to evaluation of its toxicity and harmfulness. Conventional fossil-based fuel Jet A-1 and a blend of Jet A-1 with 25 vol. % of biobutanol were tested at the same fuel flow rates. The engine working parameters such as, e.g., thrust or emission index have been determined with respect to the type of fuel. The test results have been compared and analyzed.
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W artykule przedstawiono koncepcję analizy spektralnej sygnałów fonokardiograficznych. Zaprezentowano wyniki analizy sygnałów zawierających od kilku do kilkunastu uderzeń serca oraz sygnałów krótkich zawierających pojedyncze uderzenie serca. Przedstawiono propozycje kilkudziesięciu widmowych cech dystynktywnych oraz ocenę ich przydatności w diagnostyce schorzeń kardiologicznych.
EN
The article presents the idea of spectral analysis of phonocardiographic signals. The results of analysis of signals containing from several to over a dozen heartbeats and short signals containing only one heartbeat. Proposals dozens of spectral distinctive features and evaluate their usefulness in the diagnosis of cardiac diseases.
The subject of the article concerns the issues associated with thermal degradation of aviation fuels under high temperature conditions. Due to the intensive development towards increasingly higher thermal loads for both, turbine aviation engines, as well as the used fuels, the issue of thermal stability of the fuel itself is extremely important. In aviation, the fuel, apart from direct participation in energy generation during the combustion process of a fuel-air mixture, also takes part in the heat transfer in many aircraft systems. As a result, requirements in terms of the fuel’s thermal potential are increasingly higher. The standard method for determining the thermal stability of fuel executed on a JFTOT device proves to be insufficient in the context of the appearing issues in current operation. The article presents a non-standard approach to the assessment of aviation fuel thermal degradation with the use of a specialist test rig. The authors believe that the presented methodology and the measurement capabilities of the test rig are valuable supplementary material for the standardized thermal stability test. It allows more thoroughly understanding the phenomena undergoing in the fuel impacted by high temperatures. The article has been prepared within the research project no. 2011/01/D/ST8/06567 funded by the National Science Centre in Poland.
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The paper presents issues related to the process of thermal degradation of jet fuel. This process is of a different nature depending on temperature and time, in which the fuel is subjected to thermal action. The standard method for testing the jet fuel thermal stability seems to be insufficient, therefore, the conduct of the research on a dedicated test rig was taken in this paper. The assessment of the fuel degradation process was carried out on the basis of determination of hydroperoxide and acid numbers as signs of the occurred process. The article has been prepared within the research project No. 2011/01/D/ST8/06567 funded by the National Science Centre in Poland.
PL
Tematem publikacji są zagadnienia związane z procesem degradacji termicznej paliwa lotniczego. Proces ten ma odmienny charakter w zależności od temperatury i czasu w jakim paliwo jest poddane działaniu termicznemu. Standardowa metoda badania stabilności termicznej paliwa lotniczego wydaje się być nie wystarczająca, dlatego w niniejszej pracy podjęto się przeprowadzenia badań na dedykowanym stanowisku badawczym. Ocenę procesu degradacji paliw przeprowadzono w oparciu o wyznaczenie liczby wodoronadtlenkowej i liczby kwasowej jako oznak zaistniałego procesu. Artykuł został przygotowany w oparciu o rezultaty otrzymane w ramach projektu badawczego nr 2011/01/D/ST8/06567 finansowanego przez Narodowe Centrum Nauki.
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The publication subject is the issue related to the assessment of phenomena occurring during the jet fuel thermal degradation process. The research in this article was carried out on a specialised laboratory station, according to the author’s own methodology. The assessment of the fuel degradation process was conducted on the basis of an analysis of the content of deposits collected on filters with a diameter of 0.8 µm and 3.0 µm. The filters were additionally analysed under a microscope. The results indicate that a degree and intensity of the fuel thermal degradation process are affected by the technology of the tested fuel and the test temperature. The article was prepared on the basis of the results obtained within the framework of the research project No. 2011/01/D/ST8/06567 funded by National Science Centre.
PL
Tematem publikacji jest problematyka związana z oceną zjawisk zachodzących podczas procesu degradacji termicznej paliwa lotniczego. Badania w niniejszym artykule prowadzono na wyspecjalizowanym stanowisku laboratoryjnym, według własnej autorskiej metodyki. Ocenę procesu degradacji paliwa przeprowadzono w oparciu o analizę zawartości osadów zebranych na sączkach o średnicy 0.8 µm i 3,0 µm. Sączki dodatkowo były analizowane pod mikroskopem. Wyniki wskazują, że na stopień i intensywność procesu degradacji termicznej paliwa ma wpływ technologia badanego paliwa oraz temperatura badania. Artykuł został przygotowany w oparciu o rezultaty otrzymane w ramach projektu badawczego nr 2011/01/D/ST8/06567 finansowanego przez Narodowe Centrum Nauki.
This paper presents differences between fossil fuel (Jet A-1) and alcohol/Jet A-1 blend, during combustion process using laboratory test rig with miniature turbojet engine (MiniJETRig). The test rig has been created in Air Force Institute of Technology for research and development works aimed at alternative fuels for aviation. Fuel from different feedstock (non-fossil sources) is introduced into market due to ecological aspects, fuel price stability and energy security. Application of alcohol to propel aircraft has started form using a blend of aviation gasoline with ethanol in spark-ignited internal-combustion engines. Taking into account that large part of aviation fuels used by commercial aircraft is jet fuels, so in this area it has begun to look for possibilities to apply alcohol component. In 2016, international standard (ASTM) approved a synthetic blending component for aviation turbine fuels for use in civil aircraft and engines – alcohol-to-jet synthetic paraffinic kerosene (ATJ-SPK). According to standard, ATJ-SPK synthetic blending components shall be comprised hydro processed synthetic paraffinic kerosene wholly derived from isobutanol processed through dehydration, oligomerization, hydrogenation and fractionation. Two different fuel samples, a traditional fossil jet fuel (Jet A-1) and a blend of 10% butanol with Jet A-1 were tested. Laboratory tests of selected physicochemical properties and bench tests with the same profile of engine test were carry out for both fuel samples. The obtained results: engine parameters and exhaust gas emissions are compared and discussed.
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The paper covers issues regarding lubricity of petroleum fuels used in piston and turbine engines, containing hydrocarbon biocomponents. Basing on available literature it can be said that the most prospective fuel components are biohydrocarbons. The paper describes effect of biohydrocarbons included in aviation fuel and diesel fuel on lubricity of such blends. The analysis covers two processes for obtaining biohydrocarbons, the HVO and the Fischer-Tropsch process. Due to problems with actual products acquiring, biohydrocarbons models representing chemically the actual ones from specific process. Lubricity testing was carried out according to standard test methods.
PL
Tematem publikacji są zagadnienia smarności paliw naftowych stosowanych do zasilania silników tłokowych i turbinowych zawierających biokomponenty węglowodorowe. Na podstawie przeglądu literatury można stwierdzić, że najbardziej perspektywicznymi komponentami do paliw są biowęglowodory. W artykule przedstawiono wpływ dodatku biowęglowodorów, do paliwa lotniczego oraz oleju napędowego, na smarność otrzymanych kompozycji. Analizie poddano dwie technologie otrzymywania biowęglowodorów: HVO oraz syntezę Fischera – Tropscha. Ze względu na trudności w pozyskaniu rzeczywistych produktów, przygotowano modele biowęglowodorów reprezentujące w sensie chemicznym rzeczywiste biowęglowodory z danej technologii. Badania w kierunku oceny właściwości smarnych zostały przeprowadzone w oparciu o znormalizowane metody badawcze.
This paper presents a methodology developed to measure exhaust gas emissions during operation of a miniature turbojet engine, using a laboratory test rig. The rig has been built for research and development works aimed at modelling and investigating processes and phenomena occurring in jet engines. The miniature jet engines, similarly to full–scale ones used commonly in air transport, are characterized by variable exhaust gas emissions, depending on engine operating parameters. For this reason, an attempt has been made to determine the characteristic features of miniature engine operation modes and to define the variability of operation parameters and exhaust gas emissions as a function of time. According to the authors, the preliminary tests allowed for defining specific profile of engine test, which enables proper measurement regarding exhaust gas emissions using the miniature jet engine. The paper also presents test results for Jet A-1 fuel, according to the used methodology.
A worldwide trend to popularise gradually increasing use of biofuels in various applications was a motivation for gaining interest in FAME as a commonly available biocomponent to fuels combusted in turbine engines. These engines are mainly used in aeronautics, but many of them are also used in other, non-aeronautical areas, including marine navigation. Specific conditions in which fuels are combusted in turbine engines used in these applications are the reason why fuel mixtures of kerosene and FAME type should reveal relevant low temperature characteristics. The article presents results of tests of low temperature properties of mixtures of the jet fuel Jet A-1 and methyl esters of higher fatty acids (FAME). The prepared mixtures contained different contents of FAME. The obtained results present changes of: viscosity, cloud point, pour point, crystallising point, and cold filter plugging point, depending on the percentage by volume of FAME. They also prove that the course of changes of low temperature properties of these mixtures is affected by chemical structure of the biocomponent.
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This article presents laboratory test rig with a miniature turbojet engine (MiniJETRig – Miniature Jet Engine Test Rig), that was built in the Air Force Institute of Technology. The test rig has been developed for research and development works aimed at modelling and investigating processes and phenomena occurring in full scale jet engines. In the article construction of a test rig is described, with a brief discussion on the functionality of each of its main components. Additionally examples of measurement results obtained during the realization of the initial tests have been included, presenting the capabilities of the test rig.
PL
Tematem publikacji jest laboratoryjne stanowisko hamowniane MiniJETRig (Miniature Jet Engine Test Rig) zbudowane w oparciu o miniaturowy silnik odrzutowy, wytworzone w Instytucie Technicznym Wojsk Lotniczych. Stanowisko przeznaczone jest do realizacji prac badawczo – rozwojowych, mających na celu modelowanie oraz badanie procesów i zjawisk zachodzących w rzeczywistych silników odrzutowych. W artykule przedstawiono budowę stanowiska wraz z krótkim opisem funkcjonalnym poszczególnych elementów składowych. Zaprezentowano również przykładowe wyniki pomiarowe uzyskane podczas realizacji wstępnych testów hamownianych, prezentujące możliwości badacze stanowiska.
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Purpose: The aim of this paper is to present differences of friction process occurred in research carried out on tribological apparatus with diesel fuel and biocomponent additives. The analysis of coefficient of friction and electrical resistance of kinematic pair took place. It was done for kinematic pair worked in pure diesel fuel and biofuel as a diesel fuel with fatty acid methyl ester (FAME) additives. Design/methodology/approach: The research were conducted on HFRR apparatus (dedicated for lubricity assessment of diesel fuel) and tribotester TR-2. The research were carried out with pure diesel fuel and diesel fuel with 5% and 10% (v/v) content of FAME. Findings: The results of the research indicate that on account of different construction of apparatus, the friction process assess on the basis of coefficient of friction and resistance is not identical. The FAME additive causes increase of resistance that is over the measuring range of HFRR apparatus. The fact leads to conclusion that standard assessment of lubricity should be replenish by additional analysis of coefficient of friction and kinematic pair resistance. Research limitations/implications: The research was conducted only for diesel fuel and mixtures of the fuel and FAME. Other fuels were not taken into account. Practical implications: The presented results can be used as a value directions in research development of fuels and biofuels properties. Originality/value: The standard research of fuel lubricity boils down to determine wear diameter. This paper indicates other, non-standard approach by additional parameters analysis as coefficient of friction and kinematic pair resistance that was done on tribometer TR-2.
The paper presents the application of similarity theory to investigations of transient heat transfer in materials with complex structure. It describes the theoretical-experimental method for identification and design of the structure of two-component composite walls based on the research of the thermal diffusivity for the composite and its matrix separately. The thermal diffusivity was measured by means of the modified flash method. The method was tested on two samples of double-layer ‘epoxy resin – polyamide’. All the investigated samples had the same diameter of 12 mm and thickness ranging from 1.39–2.60 mm and their equivalent value of thermal diffusivity ranging from (1.21–1.98)×10-7 m2/s. Testing the method and research on carbon/epoxy composites was carried out at temperatures close to room temperature.
This paper describes the effect of fatty acid methyl esters (FAME) content in aviation fuels and diesel fuels on lubricity of such fuel blends. Standard petroleum fuels being currently in use contain various components, including the very important ones such as FAME and biohydrocarbons. The latter ones have been used also in aviation turbine fuels. Such use is, among others, associated with limiting of harmful combustion products emission. Lubricity, as one of important parameters related to fuel, directly effects on drive units use. Insufficient fuel lubricity effects probably on extended wear or injection system failure resulting in deterioration of combustion process, emission increase, and engine itself failure. Lubricity study included in this paper was carried out basing on standard test methods with HFRR and BOCLE. The paper describes the nature of lubricity change in relation to prepared fuel blends depending on FAME volume content, as well as the initial storage effect on test results.
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Treść artykułu związana jest z aspektem wprowadzenia biopaliw do zasilania turbinowych silników lotniczych. Przedstawiono aktualne trendy dotyczące stosowania paliw alternatywnych w lotnictwie oraz problematykę związaną z wprowadzaniem biokomponentów węglowodorowych. Wskazano również na potrzebę podjęcia prac badawczo-wdrożeniowych w zakresie tej tematyki, również i w Polsce.
EN
Article is related to the aspect of the introduction of biofuels to power turbine aircraft engines. The paper presents the current trends in the use of alternative fuels in aviation and the problems connected with the introduction of hydrocarbon biocomponents. It is pointed to the need to take research and implementation works in the field of the subject, also in Poland.
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The study outlines results from the studies on applicability of 1st generation biocomponent, namely long-chain fatty acid methyl esters (FAME) of vegetable origin, as an ingredient to fuels used to supply turbine aircraft engines. The presented analysis refers to both physical and chemical properties of developed fuel mixtures of Jet A-1 pure kerosene fuel with various amounts of the FAME additive and is based on own results obtained from tests of turbine engines on workbenches. The experiment results indicate that there are virtually no chances to apply the 1st generation biocomponents of the FAME type to aircrafts, however it is possible to seek for application opportunities of such biocomponents to other turbine engines, different from the aviation engineering.
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W niniejszej pracy przedstawiono wyniki oceny przydatności biokomponentu I generacji pochodzenia roślinnego – estrów metylowych wyższych kwasów tłuszczowych (FAME) – jako komponentu do paliwa stosowanego do zasilania turbinowych silników lotniczych. Przedstawiona analiza dotyczy zarówno badań właściwości fizykochemicznych przygotowanych mieszanek paliwa Jet A-1 z różną ilością dodatku FAME, jak również opiera się na wynikach uzyskanych na stanowiskach silników turbinowych. Wyniki pracy wskazują na praktyczny brak możliwości wykorzystania biokomponentu I generacji typu FAME w lotnictwie. Jednakże uzyskane rezultaty wskazują, że można poszukiwać zastosowania tego typu biokomponentu w silnikach turbinowych w innych dziedzinach niż lotnictwo.
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Tematem opracowania jest problematyka związaną ze stabilnością termiczną paliw do turbinowych silników lotniczych. W pracy przedstawiono istotne znaczenie tego parametru w aspekcie prawidłowego przebiegu procesu spalania w silniku odrzutowym. Zaprezentowane zostało krytyczne uwagi do standardowej metodyki badawczej oznaczania stabilności termicznej oraz jej modyfikacja na potrzeby realizacji pracy badawczej, polegająca na wielokrotnym przepuszczeniu paliwa przez układ badawczy, przez co uzyskano znacznie większą selektywność wyników. Przedstawiono rezultaty badań własnych, dotyczące wpływu technologii produkcji paliwa oraz wprowadzanych do niego dodatków na zmianę stabilności termicznej.
EN
The theme of this paper is the issue related to the thermal stability of aviation fuel to turbine jet engine. This paper presents the importance of this parameter in terms of the proper conduct of the combustion process in a jet engine. In paper were presented critical remarks of the standard test method of determining the thermal stability and its modification for the needs of realization of the research work, relying on multiple pass of fuel through the test system, which resulted in a greater selectivity results. In article presented the results of own research, on the effects of technology fuel production and additives put into fuel on change the thermal stability.
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