著者

Jun Daesu Ishii Kazuaki Iida Norimasa

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.46, no.1, pp.60-67, 2003-02-15

被引用文献数

1

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Homogeneous charge compression ignition (HCCI) is regarded as the next generation combustion regime in terms of high thermal efficiency and low emissions. It is difficult to control autoignition timing and combustion duration because they are controlled primarily by the chemical kinetics of fuel-air mixture. In this study, it was investigated the characteristics of autoignition and combustion of natural gas in a 4 stroke HCCI engine. And also, to clarify the influence of n-butane on autoignition and combustion of natural gas, it was changed the blend ratio of n-butane from 0 mol % to 10 mol % in methane/n-butane/air mixtures. Autoignition strongly depends on incylinder gas temperature. Autoignition of natural gas occurs when in-cylinder gas temperature reaches in a range of 1 000 ± 100 K under this experimental condition. To realize high thermal efficiency and low CO emissions, it is necessary to prepare operation conditions that maximum cycle temperature is over 1 500 K. Autoignition temperature is 25 K lower by increasing n-butane blend ratio of 10%. As the blend ratio of n-butane increases, the maximum cycle temperature increases, and THC, CO emissions reduce.

著者

Takada Naoki Tomiyama Akio

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.49, no.3, pp.636-644, 2006-08-15

被引用文献数

7 24

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For interface-tracking simulation of incompressible two-phase fluids with high density ratios, a new numerical method was proposed by combining Navier-Stokes equations with a phase-field model based on a van der Waals-Cahn-Hilliard free-energy theory. The method was applied to several benchmark problems. Major findings are as follows: (1) The volume flux derived from a local chemical potential gradient in the Cahn-Hilliard equation leads to accurate volume conservation, autonomic reconstruction of gas-liquid interface, and reduction of numerical diffusion and oscillation. (2) The proposed method gave good predictions of pressure increase inside a bubble caused by the surface tension force. (3) A single liquid drop falling in stagnant gas and merging into a stagnant liquid film was successfully simulated.

著者

Hwang Jaeho Yoon Tae-Seok Lee Dong-ho LEE Soo-Gab

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.44, no.3, pp.451-464, 2001-08-15

参考文献数

18

被引用文献数

21

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In order to study unsteady flowfield around high speed trains passing by each other, a three-dimensional inviscid numerical method based on three types of domain decomposition techniques is developed. Roe’s FDS scheme is used for the space discretization, and LU-SGS method is adopted for the time integration. After validation of the code to a single track train/tunnel interaction problems with three dimensional tunnel configuration, the numerical simulations of the trains passing by on the double-track are performed for the 5 different cases using 3 basic parameters; e.g. nose shape, existence of tunnel, and train length. After the parametric study, variational parametric studies are carried out to understand the effects of the velocity of the train, the gap between the train and the blockage ratio. Firstly, train/tunnel interaction problems for double track railway system are investigated and aerodynamics loads histories during the crossing events—train/train interaction problem—are presented and discussed.

著者

Lee Hsing-Juin Chang Chih-Luong

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.44, no.4, pp.658-667, 2001-11-01

参考文献数

27

被引用文献数

2 3

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The kinetic power and efficiency equations for general jet propulsion systems are classically given in a much cursory, incomplete, and ununified format. This situation prohibits the propulsion designer from seeing the panorama of interrelated propulsion parameters and effects. And in some cases, it may lead to an energy-inefficient propulsion system design, or induce significant offset in propulsion performance as demonstrated in this study. Thus, herein we attempt to clarify some related concepts and to rigorously derive the associated generalized equations with a complete spectrum of physical parameters to be manipulated in quest of better performance. By a highly efficient interweaved transport scheme, we have derived the following equations for general jet propulsion systems: i.e., generalized total kinetic power, generalized kinetic power delivered to the jet propulsion system, generalized thrust power, generalized available propulsion power, and relevant generalized propulsive, thermal, and overall efficiency equations. Further, the variants of these equations under special conditions are also considered. For taking advantage of the above propulsion theories, we also illustrate some novel propulsion strategies in the final discussion, such as the dive-before-climb launch of rocket from highland mountain on eastbound rail, with perhaps minisatellites as the payloads.

著者

Radu Rosca Edward Rakosi Comsa Iulian-Agape RADU Gaiginschi

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.44, no.4, pp.634-640, 2001-11-01

参考文献数

4

被引用文献数

2

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The paper presents the application of a three component model to the theoretical study of the combustion process of a Diesel engine fueled with sunflower oil and sunflower oil-Diesel fuel mixtures. The model assumes that the working fluid consists of three components: the fresh air, the flame and the burned gases.<BR>The combustion model uses the energy conservation equation:<BR>v<SUB>c</SUB>·Q<SUB>c</SUB>·dξ<SUB>α</SUB>=dU<SUB>α</SUB>+dL<SUB>α</SUB>+dQ<SUB>wα</SUB>, [1]<BR>where v<SUB>c</SUB> is the fuel cyclic dose, Q<SUB>c</SUB> is the fuel heating value, ξ<SUB>α</SUB>=v<SUB>cα</SUB>/v<SUB>c</SUB>, v<SUB>cα</SUB> is the quantity of burned fuel up to the moment α, U<SUB>α</SUB> is the internal energy of the working fluid, Q<SUB>wα</SUB> is the heat exchanged through the cylinder walls and L<SUB>α</SUB> is the mechanical work.<BR>The heat release law was assumed to be a Vibe type one:<BR>ξ<SUB>α</SUB>=R<SUB>c</SUB>·[1−exp(−6.9·A<SUP>m</SUP><SUB>P</SUB><SUP>p+1</SUP>)]+(1−R<SUB>c</SUB>)·[1−exp(−6.9·A<SUP>md+1</SUP>)], [2]<BR>where:<BR>·A<SUB>p</SUB>=(α−α<SUB>d</SUB>)/(α<SUB>P</SUB>−α<SUB>d</SUB>) and A=(α−α<SUB>d</SUB>)/(α<SUB>F</SUB>−α<SUB>d</SUB>);<BR>·α<SUB>d</SUB>-start of combustion angle;<BR>·α<SUB>f</SUB>-end of combustion angle;<BR>·α<SUB>P</SUB>-end of rapid combustion angle.<BR>Using Eqs. [1] and [2] we have obtained the cylinder pressure during combustion, for the vegetable fuels taken into account; the peak values were confirmed during the experiments.

著者

Ujita Hiroshi Ikeda Takashi Naitoh Masanori

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.45, no.3, pp.607-614, 2002-08-15

参考文献数

14

被引用文献数

5

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SAMPSON is the integral code for severe accident analysis in detail with modular structure, developed in the IMPACT project. Each module can run independently and communication with multiple analysis modules supervised by the analysis control module makes an integral analysis possible. At the end of Phase 1 (1994 - 1997), demonstration simulations by combinations of up to 11 analysis modules had been performed and physical models in the code had been verified by separate-effect tests and validated by inegral tests. Multi-dimensional mechanistic models and theoretical-based conservation equations have been applied, during Phase 2 (1998 - 2000). New models for Accident Management evaluation have been also developed. Verificaton and validation have been performed by analysing separate-effect tests and inegral tests, while actual plant analyses are also being in progress.

著者

Tokumasu Takashi Matsumoto Yoichiro

出版者

一般社団法人日本機械学会

雑誌

JSME international journal. Ser. B, Fluids and thermal engineering (ISSN:13408054)

巻号頁・発行日

vol.43, no.2, pp.288-295, 2000-05-15

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In our 3rd report, we introduced a Lennard-Jones (LJ) potential parameter based on the potential obtained by ab initio calculation and collision cross section from the Wang-Chang, Uhlenbeck and Taxman's theory and molecular dynamics (MD) simulation. In the present study, we have improved the dynamic molecular collision (DMC) model to callculate the property of MD simulation better than the previous model. To confirm its validity we calculated the equilibrium state, the transport coefficient (viscosity coefficient and heat conductivity) at various temperatures and the normal shock wave by the direct simulation Monte Carlo (DSMC) method using the DMC model and compared the results with other theoretical and experimental results. Consequently, we found that the diatomic rarefied gas flows could be simulated very well using our model. These results were compared with those obtained by the Larsen Borgnakke model. It was found that this model was more efficient than the previous model.