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1

Experimental analysis of noise and vibration of a diesel engine

Kilikevičienė K., Fursenko A., Kilikevičius A., Vainorius D., Matijošius J., Rimkus A., Bereczky A.

Journal of KONES

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2018

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Vol. 25, No. 1

225-232

EN

Noise and vibration of ignition compression engine is one of the most complicated fields to cope with since every mechanism that compose of the engine affect them separately. In this study, effect of diesel on engine noise and vibration has been studied on an unmodified compression ignition engine. Noise and vibration characteristic of a direct ignition engine, which was fuelled with diesel, were investigated. With the usage of equations obtained from regression analysis, estimation of engine characteristic fuelled with various biodiesels researches were carried out. Tests were conducted at fixed injection timing of diesel fuel. The first system is for diesel fuel injection; the second one is PFI (port-fuelled injection) and is used for injecting alcohol into the engine intake manifold. The engine applied to this study was a naturally aspirated, 3in-line, IVECO AIFO 8031 i06.05 diesel engine with direct injection. Experiments were conducted in a sound insulated room. For each experiment, vibration data gathered from the engine block with 3.2 kHz (for vibration) for 2 s and with 20 kHz sampling frequency for 0.320 s. All measurements were performed under conditions: angle 10; 4 different loads (4, 8, 12 and 20 kW).

2

Evaluating combustion, performance and emission characteristics of CI engine operating on diesel fuel enriched with HHO gas

Rimkus A., Pukalskas S., Juknelevičius R., Matijošius J., Kriaučiūnas D.

Journal of KONES

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2018

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Vol. 25, No. 2

303--311

EN

Research of efficient and ecological parameters was carried out with compression ignition (CI) engine using diesel fuel and additionally supplied hydrogen and oxygen (HHO) gas mixture. HHO gas is produced by electrolysis when the water was dissociating. At constant engine‘s brake torque and with increasing HHO gas volumetric concentration in taken air up to 0.2%, engine efficient indicators varies marginally, however, with bigger HHO concentration these parameters becomes worse. HHO increases smokiness, but it decreases NOx concentration in exhaust gas. Numerical analysis of combustion process using AVL BOOST software lets to conclude that hydrogen, which is found in HHO gas, ignites faster than diesel fuel and air mixture. Hydrogen combustion before TDC makes a negative work and it changes diesel fuel combustion process – diesel ignition delay phase becomes shorter, kinetic (premixed) combustion phase intensity gets smaller.

3

Structures of Turbulent Vortices in Floodplains of Compound Channels

Rimkus A.

Archives of Hydro-Engineering and Environmental Mechanics

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2016

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Vol. 63, nr 4

281--295

EN

In turbulent flows, several kinds of vortices and their structures are developed. After physical summation al velocities created by them, they intertwine, and the picture obtained from their measurement chronograms is mostly chaotic. Consequently, these structures become masked. It is therefore very difficult to investigate them and despite many studies performed so far, they have not been sufficiently explored. Favorable conditions for investigations of velocity measurement chronograms occurred when sufficient long intervals were observed, in which the above mentioned masking is minimal. In such intervals, the investigation of turbulent vortices and their structures becomes possible, and it has been performed to some degree. The results of these investigations of the compound channel were already discussed in two previously published articles. The first describes all vortices and their structures in the whole water flow of the compound channel. The second contains a detailed analysis of vortices and their structures in the central vertical of the main channel. This article, discuss investigations of coherent structures formed in the floodplain.

4

Investigation of combustion, performance and emission characteristics of spark ignition engine fuelled with buthanol – gasoline mixture and a hydrogen enriched air

Rimkus A., Melaika M., Matijošius J., Mikaliūnas Š., Pukalskas S.

Advances in Science and Technology. Research Journal

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2016

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Vol. 10, nr 31

102--108

EN

In this study, spark ignition engine fuelled with buthanol-gasoline mixture and a hydrogen-enriched air was investigated. Engine performance, emissions and combustion characteristics were investigated with different buthanol (10% and 20% by volume) gasoline mixtures and additionally supplied oxygen and hydrogen (HHO) gas mixture (3.6 l/min) in the sucked air. Hydrogen, which is in the HHO gas, improves gasoline and gasoline-buthanol mixture combustion, increases indicated pressure during combustion phase and decreases effective specific fuel consumption. Buthanol addition decreases the rate of heat release, the combustion temperature and pressure are lower which have an influence on lower nitrous oxide (NOx) emission in exhaust gases. Buthanol lowers hydrocarbon (HC) formation, but it increases carbon monoxide (CO) concentration and fuel consumption. Combustion process analysis was carried out using AVL BOOST software. Experimental research and combustion process numerical simulation showed that using balanced buthanol and hydrogen addition, optimal efficient and ecological parameters could be achieved when engine is working with optimal spark timing, as it would work on gasoline fuel.

5

Structure of Turbulent Vortices in a Compound Channel

Rimkus A.

Archives of Hydro-Engineering and Environmental Mechanics

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2012

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Vol. 59, nr 3-4

113-135

EN

In spite of many investigations performed on turbulent flows, their structure has not yet been sufficiently explored. The difficulty is that, when a detailed picture of the velocity field is necessary, the widely employed Particle Image Velocity (PIV) method can provide photos covering only a short interval of flow, which cannot include the largest structures of turbulent flow, and consequently these structures cannot be investigated. In this study, the author tried to obtain necessary data about the processes occurring in the flow by analyzing instantaneous velocity measurements carried out by 3D means. A measurement at the points of a low cross-section takes at least 1 minute. During this time all vortex structures, including the largest, occur repeatedly many times and can be studied. The analysis of such measurements was the aim of this article. The process of the generation of vortices at the bottom and their further development, including the conditions of the development of the largest vortices, has been investigated. The results of these investigations are discussed in this article.

6

Conveyance calculation for channels overgrown with grass by applying hydraulic equivalent thickness of grass layer

Rimkus A.

Journal of Water and Land Development

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2000

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no. 4

123-135

EN

The slopes of canalised brooks and ditches, which are the drainage water receivers, including open channels of other purposes are usually overgrown by grass. The slopes of naturalised channels are seldom if ever mowed. Therefore, when performing hydraulic calculations (for an average discharge at vegetation time, a maximum discharge during summer floods), it must be presumed that these channels are overgrown with luxuriant grass of 50-70 cm height. Thus, by estimating channel conveyance, i.e., possibility to allow the vegetation to exist, it is necessary to take the grass influence into account. For this purpose, it was necessary to work out a hydraulic calculation method for such channels. In the Lithuanian Institute for Water Management, a hydraulic calculation model was developed for naturalised channels overgrown by trees and grasses (RIMKUS, 1996). To estimate the grass influence, the hydraulic research data published by DĄBKOWSKI and POPEK (1997) (Warsaw Agricultural University) were employed. To apply these data it was necessary to employ the method of equivalent hydraulic bottom.

PL

Wiele z rowów naturalnych cieków wodnych zarasta roślinnością trawiastą. Zmienia ona hydrauliczne właściwości koryt w tym także spadek hydrauliczny w korytach poddawanych zabiegom renaturalizacyjnym. Prowadząc obliczenia przepustowości takich koryt trzeba uwzględniać możliwość ich zarastania trawami o wysokości do 50-70 cm. Przyjęto, że praktyczniej jest w obliczeniach stosować współczynnik szorstkości i głębokości strumienia odnoszone do powierzchni pochylonych traw. Wykorzystując dane z doświadczeń DĄBROWSKIEGO i POPKA [1997] sporządzono dla trzech natężeń przepływu q zależności współczynnika szorstkości n1 od głębokości h1, odnoszących się do przekroju strumienia do dna koryta (tab. 1 i rys. 1). Z krzywych wyrównujących te zależności odczytano wyrównane wartości odpowiadających sobie n1 i h1. Przyjęto, że w analizowanym przypadku (gładkie szklane ściany boczne) promień hydrauliczny jest równy głębokości wody. W dalszych analizach wprowadzono pojęcie zastępczego dna koryta na poziomie wierzchołków przygiętych traw. Głębokość strumienia wody przy takim założeniu wynosi h = h1 - t, gdzie t jest grubością przygiętych traw. Stosując wzór Chezy'ego dla całego przekroju i dla przekroju zastępczego o głębokości h i odpowiadającego jej współczynnika szorstkości n uzyskano wyrażenie (4), a następnie ze wzoru (5) na grubość warstwy traw t. Ze wzoru (5) obliczono wartości t przy założeniach czterech wartości współczynnika szorstkości warstwy przygiętych traw n i zebrano je w tabelach 3-6. Zmianę współczynnika szorstkości n wyrażono wzorem (6), w którym hgr jest wysokością traw w analizowanych doświadczeniach. Do obliczeń grubości warstwy przygiętych traw t użyto wzoru (7). Współczynniki liczbowe a1-a5 występujące w tym wzorze obliczono na podstawie wyników wspomnianych doświadczeń dla dwóch przypadków, opisanych wzorami (9) i (11). Wysokość traw w doświadczeniach wynosiła 0,35 m.

7

Model for hydraulic calculations for naturalised channels

Rimkus A., Vaikasas S.

Journal of Water and Land Development

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1999

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no. 3

101-111

EN

Naturalisation of channels - water receivers can increase their hydraulic resistance too much. Therefore the hydraulic calculations on such channels are necessary. The existing calculation methods are not sufficiently precise. In this paper the necessary development of these calculations is described.

PL

Przywracanie naturalnego charakteru korytom rzek uregulowanych pełniących rolę odbiorników wód z obiektów odwadnianych prowadzi do wzrostu hydraulicznych oporów przepływu. Przyczyną tego wzrostu mogą być wprowadzane na skarpy drzewa i krzewy, zmieniające przy wysokich przepływach warunki ruchu wody. Złożone warunki przepływu wymagają stosowania innych metod obliczeń takich koryt. Autorzy opracowali układ równań opisujących opory i warunki przepływu w poszczególnych częściach przekroju poprzecznego, uwzględniających współczynniki oporu przepływu od zastępczej geometrii i rozkładu drzew. Rozwiązanie tego układu równań metodą iteracji jest możliwe zarówno dla ruchu równomiernego jak i nierównomiernego. Poprzez schematyzację przekroju koryta można tę metodę stosować do obliczeń koryt o przekrojach nieregularnych lub zdeformowanych.