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1

Pomiary szybkości spalania mieszanki eteru dimetylowego z powietrzem przy użyciu techniki mikrociążenia

Okajima S.

Silniki Spalinowe

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2005

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R. 44, nr 3

56--60

PL

Przeprowadzono doświadczenie, którego celem było sprawdzenie charakterystyki spalania mieszanki powietrza i eteru dimetylowego przy wykorzystaniu technikę mikrociążenia, wymagające komory swobodnego opadania. Warunki początkowe badań były następujące: temperatura 293 K, ciśnienie 0,10 MPa a stosunek składników mieszaniny zmieniał się od stechiometrycznego do granic zapalności mieszanki. Uzyskano następujące wyniki: (1) technika mikrociążenia jest bardzo użyteczna w analizie zachowania płomienia, nawet dla bardzo ubogich mieszanek, oraz (2) szybkość spalania mieszanki eteru dimetylowego jest podobna do prędkości spalania metanu w całym zakresie analizowanych składów mieszaniny i wynosi 10,0 cm/s oraz 32,0 cm/s, odpowiednio dla mieszanki o stosunku 0,62 i 0,90 a także (3) na podstawie wyników badań można wnioskować, że użycie mieszanki z eterem dimetylowym nie jest wykluczone w przypadku silników.

EN

Experiment has been carried out to examine the fundamental combustion characteristics of DME fuel-air mixtures using micro-gravity technique, which is achieved in freely falling chamber. The initial conditions of temperature and pressure are 293 K and 0.10 MPa, respectively and the equivalence ratio is the range from stoichiometoric proportion to near the lower flammability limit. The results obtained in the study are as follows:(1) micro-gravity technique is very useful to analyze the flame behavior even at very lean mixtures, and (2) the burning velocity of DME fuel- air mixture is nearly the same with that of methane-air mixture at the range of all the equivalence ratios investigated and those values of DME fuel are 10.0 cm/s and 32.0 cm/s at 0.62 and 0.90 of equivalence ratio, respectively, and (3) from these experimental data it is suggested that the application to the engine combustion of DME fuel is not so impossible.

2

Combustion characteristics of lean propane-air mixture by using high ignition energy

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2004

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Vol. 11, No. 1-2

308-313

EN

Experiments have been carried out to examine the combustion characteristics of propane-air mixtures under normal gravity and microgravity conditions by using high ignition energy in a combustion tubę. The microgravity technique achieved in a freely falling chamber is employed because the realizations of symmetrical flame propagations in a tubę are possible. Experimental condition for the initial mixtures corresponds to room temperature and 0.1 MPa and the fuel used is propane of 99.9% purity. The main conclusions are as follows: (J) The flame speed monotonically decreases with decreasin the equivalence ratio under normal gravity and microgravity. (2) The probability of the irregular flame propagation for both fuels under microgravity are larger than that under normal gravity at same equivalenence ratio. (3)The range of distance of flame propagation under normal and microgravity conditions by using high ignition energy can possible to distinguish.

3

A study of flame propagation limit of very lean propane-air mixture in a combustion tube

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2003

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Vol. 10, No. 3-4

149-153

EN

Experiments have been carried out with extremely lean, quiescent propaneair mixtures to examine the influence of flame propagation direction under normal gravity and microgravity conditions on propagation limit and distance of flame propagation in a tube. The microgravity technique achieved in a freely falling chamber is employed because the realizations of symmetrical flame propagations in a tube are possible. Experimental condition for the initial mixtures corresponds to room temperature and 0.1 MPa and the fuel used is propane of 99.9% purity. The experimental results show that the range of distance of flame propagation under normal and microgravity conditions can possible to distinguish under follows: i)Range : the flame propagation was observed under normal and microgravity conditions (Flammability limit), ii)Range : the flame propagation was influence by gravity condition (Unsteady Range), iii)Range �f: under microgravity the flame propagation was observed (Microgravity Range) and iv)Range‡V : the flame propagation was not observed under normal and microgravity conditions (Without flammability limit under normal and microgravity conditions).

4

Some new experimental observations of combustion characteristics near lean limit in a tube under microgravity

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2002

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Vol. 9, No. 1-2

110-116

EN

Experiments have been carried out with extremely lean, quiescent propane-air mixtures to examine the behavior of irregular flame propagation and to examine the lean limits of flame propagation in a tube under microgravity. The microgravity technique achieved in a freely falling chamber is employed because the realizations of symmetrical flame propagations in a tube are possible. Experimental conditions for the initial mixtures correspond to room temperature and 0.1 MPa and the fuel used is propane of 99.9% purity. The experimental results show that (1) though the lean limit of the flame propagation in a tube decreases with increasing diameter, it holds constant when the tube diameter is more than 50 mm, (2) with a large combustion tube, the lower flammability limit shifts to as low as . = 0.15 of equivalence ratio under microgravity, (3) the irregular flame fronts of cellular nature are observed in a narrow range of 0.35 < . < 0.55 under microgravity, (4) the lowest measured value of flame speed is of the order of 11.5 cm/s under microgravity which is less than half of that observed under normal gravity, and (5) the influence of radiation from the wall in a tube on flame speed appears negligible.

5

Influence of exhaust gas recirculation on combustion characteristics under high temperature and pressure using opposed rapid compression machine

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2002

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Vol. 9, No. 1-2

104-109

EN

The release of NOx, SOx, HC and CO2 from internal combustion engines is still a major issue in the development of modern engines. Especially when new concepts like EGR (Exhaust gas recirculation) are developed, detailed information about the pollutant formation is required. However, the experiments of actual standard engines are generally very complicated processes including the residual gas of last cycle and the flow in an engine cylinder. Thus, experimental data measured using actual engines become unreliable. To obtain the essential data on combustion of hydrocarbon-CO2-N2-O2 mixtures, the experiments have been performed under conditions of high temperature and pressure, which are achieved by a spark ignited opposed rapid compression machine. The main conclusions are follows: (1) Flame speed decreases with increasing the concentration of carbon dioxide. (2) The reduction rate of the flame speed decreases with increasing the compression ratio.(3) The ratio of decrease of flame speed increases with increasing carbon dioxide concentration.

6

A study of combustion characteristics of hydrocarbon-air mixtures at high temperature and pressure by using rapid compression machine

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2001

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Vol. 8, No. 1-2

52-57

EN

Experiments have been carried out with quiescent hydrocarbon-air mixtures for determining their combustion characteristics, under high temperature and pressure using a single and an opposed rapid compression machine with spark ignition. The absolute value of pressure exponent for methane-air and propane-air mixtures increases with increasing initial temperature and the temperature exponent is estimated to be about 2.6 even at high temperature and pressure conditions.

7

A study of combustion mechanism of propane-air mixtures near the ignition limit under microgravity

Kawakami T., Okajima S., Teodorczyk A.

Journal of KONES

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2000

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Vol. 7, No. 1-2

258-264

EN

The present experiments have been carried out with quiescent very lean propane-air mixtures for examining the lower limits of flame propagation, lower limits of ignition and minimum flame speed under microgravity. The drop shaft operated by the Micro-Gravity Laboratory of Japan (MGLAB) was used in order to produce microgravity conditions. Duration of microgravity conditions was about 4.5 s. The main conclusions are as follows: 1) microgravity experiments mąkę possible to determine the true values of the flame propagation limits; 2) the equivalence ratio at the propagation limit is lower under microgravity conditions than that under normal gravity.