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Article type: Cover
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Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Article type: Appendix
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App1-
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Article type: Index
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Toc1-
Published: August 05, 2003
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Yoshiro KATO, Takamitu YOSHIMOTO, Kouichiro KINOSHITA, Toshimi TAKAGI
Article type: Article
Pages
1-2
Published: August 05, 2003
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The flame stability limits essentially define the fundamental operation of the combustion system. The critical conditions at the stability limits are highly dependent on flow configurations and some species of fuels. For various species of fuels (Methane and Hydrogen). the flame-base stability mechanism for flame holding has been studied. In this study, the transition behavior from the stable flame attached to nozzle rim to lifting and blow off is observed experimentally, when the oxygen concentration of the co-flowing air is different. The lifting and blow-off criteria are proposed for the diffusion flame. Experiments were conducted to investigate the flame structure for various nozzle diameters from 0.14 to 8.1mm. The results obtained are as follows. The color distinction of a flame became dimmer, as the oxygen concentration of co-flowing air is smaller. The behaviors and stability of the diffusion flame depend on the spout velocity and the oxygen concentration of co-flowing air.
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Naoshi KUBO, Takamitu YOSHIMOTO, Kouitirou KINOSITA, Yosirou KATOU, To ...
Article type: Article
Pages
3-4
Published: August 05, 2003
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The flame holding at the burner in one of the essential parts for high performance combustion. Flame holding and lifting/blow-off at the burner rim and the stabilization mechanism have been researched. The nozzle diameter (curvature) at the upstream end of the diffusion flame adjacent to the burner rim plays important roles for holding the flame. The inverse diffusion flame (IDF) is the flame where the fuel and air streams of a normal round co-flowing diffusion flame (NDF) are reversed. The objective of the present study is to get further understanding lifting/blow-off in the inverse diffusion flame (IDF) and present clearer understandings of the processes of the flame holding at the burner rim.
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Daisuke YOKOI, Yojiro ISHINO, Hirotaka KATO, Norio OHIWA
Article type: Article
Pages
5-6
Published: August 05, 2003
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In order to elucidate the enhancement mechanisms of turbulent flame propagation, it is indispensable to examine and clarify the detailed process of vortex-flame interaction. In this investigation the plane shear flow between two parallel walls in numerically simulated by using the discrete vortex method. Two parallel walls are set to stabilize discrete vortices. The effect of the acoustic excitation is replaced by small fluctuation of the flow velocity. while that of the volumetric expansion is expressed by the source on the flame front. In this paper the flame propagation behavior in the plane shear flow is numerically analyzed and compared with the experimental results. It is found that the calculated flame propagation velocities agree well with those experimentally measured.
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Tadashige KAWAKAMI
Article type: Article
Pages
7-8
Published: August 05, 2003
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Experiments have been carried out with extremely lean, quiescent propane-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 main conclusions are follows : (1) a flame behavior is affected by the direction and gravity conditions, (2) the minimum flame speed of lean propane-air mixtures under microgravity is about 10cm/s, (3) under microgravity the propagation limit sifts to lower value more than that obtained under normal gravity.
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Kazushige KIKUTA, Atsushi ISHIKAWA, Takafumi SASAKI, Yukio HISHINUMA, ...
Article type: Article
Pages
9-10
Published: August 05, 2003
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There is seldom the data on the radiative property of semiconductor wafers. It is importance to know radiative properties of the wafter with a thin film for the accurate measurement of wafter temperature using the radiative thermometer and the estimation of the film thickness at in-situ. We measured the spectral normal emissivity of silicon wafters with various films without changing the condition of a thin film at 600℃ and 900℃. The result showed that radiation characteristics greatly differ by film kind and film thickness. It seems to be able to the estimation of the film thickness in the process by measuring the infrared spectrum at in-situ using this property.
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Takahiro Ohmura, Toshio Tomimura
Article type: Article
Pages
11-12
Published: August 05, 2003
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We have designed a thermal conductivity measuring apparatus using the Cyclic Heat, the Transient Hot Wire, and the Hot Disk methods. Using the apparatus, the thermal conductivities of Polyurethane foams were measured in the temperature range from -170℃ to 25℃. Comparison of measured values using the Transient Hot-Wire method with the Cyclic Heat and the Hot Disk methods indicated good agreement. It was confirmed that the results of measurement using different methods agree with each other under the conditions of using the same specimen and conducting measurements under the same environment. However, measured values using the Cyclic Heat method at temperatures near 0℃ were larger than those obtained by other methods. It was because that, when a heat wave with the amplitude about 4℃ was conducting through the specimen, the moisture in the specimen changed phases (between ice and water) periodically. Measured values using the Hot Disk method in the temperature range from -170℃ to -120℃ were smaller than the others.
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Hiroyoshi KOIZUMI, Toshihiro KOIDE, Masaya SERIZAWA
Article type: Article
Pages
13-14
Published: August 05, 2003
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A simple measurement method of micro flow rates with high precision is proposed for industrial use. Poiseuille flow is obtained within a very short entrance length in the case of low Reynolds number flows. A locally accelerated thermal flow is produced by a small spot heater, which is placed in the center part of the downwardly directed Poiseuille flow. Flow rate in a pipe can be obtained by using the linear relationship between the locally accelerated velocity due to the buoyancy force and the flow rate (maximum velocity is two times larger than the mean velocity in a Poiseuille pipe flow). The validity of measuring the flow rates below 0.1mL/min was confirmed by the numerical simulation using the unsteady two-dimensional Boussinesq equations.
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Toru KOMORIYA, Kimiyoshi TAKADA
Article type: Article
Pages
15-16
Published: August 05, 2003
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In order to simulate a quenching process, we have developed a simple calculation method in consideration of the cooling oil flow. We calculated the boiling heat transfer by coupling of the thermal conduction analysis and the thermal flow analysis. From the verification result using a bearing race, the effectiveness of this method was confirmed. In this paper, we present the outline of this calculation method and its inspection result.
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Tetsuaki TAKEDA, Hirofumi OHASHI, Yoshiyuki INAGAKI
Article type: Article
Pages
17-18
Published: August 05, 2003
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A technology development of a hydrogen production system by a nuclear heat are being performed as a heat application system of a high-temperature gas cooled reactor in the Japan Atomic Energy Research Institute. The objective of this study is to clarify heat transfer characteristics of the steam reformer in the HTTR hydrogen production system. An experiment has been performed using a double coaxial vertical tube to obtain the heat transfer characteristics and to evaluate the effectiveness of heat transfer enhancement. The amount of produced hydrogen increases with increasing not only reaction rate of catalysis but also the heat transfer coefficient. It is necessary to take into account of heat transfer from both surfaces of the double coaxial tube in order to obtain the amount of transferred heat from the heated tube to the coolant gas.
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Akiko OKAJIMA, Toshio KUROSAKA, Mamoru SUYARI, Satoshi OKAJIMA
Article type: Article
Pages
19-20
Published: August 05, 2003
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The experiment has been carried out to elucidate the fundamental combustion characteristics of solid water fuels in high temperature and low oxygen atmosphere by using the flowing combustion gas. The results obtained here are as follows : the combustion behavior of solid waste fuels in flowing combustion gas can be classified into three sequential regimes of ignition luminous flame and surface combustion, and the ignition delay in very insensitive for the increase of oxygen concentration, though it is very sensitive for the increase of ambient temperature.
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Ryuji YAMAKITA, Yojiro ISHINO, Tsuyoshi SATO, Shigeo KURODA, Masaki KA ...
Article type: Article
Pages
21-22
Published: August 05, 2003
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In order to utilize chemical properties of recycled plastic-resin as hydro-carbon fuel for industrial burner systems, a commercial LPG-fueled ceramic burner has been improved to burn plastic-resin powder as an auxiliary fuel. Within the range of a replacement rate of PET-resin powder of 0∿30%, the proposed twin-fueled burner exhibited reasonable combustion characteristics in the in-furnace operation. In this paper, polyethylene-resin is employed as another auxiliary fuel and effects of molecular construction and diameter of resin-powder on the out-of-furnace and in-furnace combustion characteristics are investigated under a constant replacement rate of 15% and a constant total heat input of 11.6kW, while the overall equivalence ratio is varied in the range of 0.63∿1.4.
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Tsuyoshi SATO, Ryuji YAMAKITA, Yojiro ISHINO, Shigeo KURODA, Masaki KA ...
Article type: Article
Pages
23-24
Published: August 05, 2003
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In order to examine possibility of energy recycling of waste PET-bottles, a commercial LPG-fueled ceramic burner has first been improved to burn PET-resin powder as an auxiliary fuel. In this paper, under the fixed conditions of a total heat input of 11.6kW and overall equivalence ratio of 0.8,combustion characteristics of the improved burner are experimentally investigated both in the open atmosphere and in the model furnace by varying a mean diameter of PET-powder. According to the results obtained in the open atmosphere burner operation, it is found that the improved burner leaves an appreciable amount of PET-powder unburnt, and that the unburnt rate increases in proportional to the mean diameter. In the in-furnace operation, on the other hand, no PET-powder is detected after the operation under a replacement rate of 15%, and the improved burner exhibits fine combustion properties comparable to the original LPG-fueled ceramic burner.
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Toshio TOMIMURA, Youji HONDA, Kouji HAMANO, Ryozo ECHIGO
Article type: Article
Pages
25-26
Published: August 05, 2003
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To investigate the effect of fin configuration on the total heat recovery rate H_<*.N> of a multi-layered type of gas-to-gas heat exchanger, a series of experiments have been performed. From the experiments, it is clarified that walls with equally spaced four straight fins of 1mm in thickness, 53mm in height and 155mm in length have little or rather reverse effect on H_<*.N>. On the other hand, walls with equally spaced three zigzag fins of 1mm in thickness, 53mm in height and 463mm in overall length are shown quite effective to increase H_<*.N>.
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Takeo TAKASHIMA, Hiroshi SHIOTA
Article type: Article
Pages
27-28
Published: August 05, 2003
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The evaporation characteristics of an emulsion droplet of Oil-in-Water (O/W) type have been conducted experimentally. The evaporation time per initial surface area of droplet τ^* is used to compare a water droplet and an emulsion droplet. As the results, τ^* of an O/W emulsion droplet is shorter than a water droplet in the Leidenfrost film boiling regime. The four evaporation modes of O/W type emulsion droplets were observed and these depended on the mixing ratio of water and oil G_s and hot surface temperature T_w G_s increases the Leidenfrost temperature of the emulsion droplet which is used to die-cast releasing agent. The microexplosion which occurs during the Leidenfrost film boiling were also observed when T_w was higher than 250℃.
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Masanori KIYOTA, Itsuki MORIOKA, Daisaku HASE
Article type: Article
Pages
29-30
Published: August 05, 2003
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Previously, numerical model for absorption within vertical pipes was proposed. Agreements were good for pipes with OD 25-15mm except 10mm or smaller. For smaller diameters, the difference between the surface area of the falling liquid film and that of the outer surface of the pipe is not negligible and the thickness of the liquid film is neither negligible. A new model is formulated in cylindrical coordinates and experiments using pipes with 9.52mm and 7mm OD are done. Smooth pipes and two kinds of internally finned pipes, which are originally developed and used to enhance the heat transfer characteristics of evaporator and condenser of refrigerator using HFC as refrigerant, are tested in the experiments. The absorption performance is enhanced by 30% compared to the smooth pipes, but the difference between the finned pipes are small.
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Yuuya SHIRAYAMA, Hiroshi CHIDA, Nobuo KURIHARA
Article type: Article
Pages
31-32
Published: August 05, 2003
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This paper describes a computer simulation of absorption refigerting system. It is a burden to repeat a trial production for the optimization according to environmental conditions or the use, when carrying out design manufacture of the Absorption Refigerting. The possibility of the prior evaluation by Computer Simulation was tried in this research. It enabled it for incorporating various kinds of design data as map data on the basis of a dynamic physics model to estimate the performance not only at a constant usual state but the time of excessive. The tried simulation reports the influence affect a system performance with different absorption liquid.
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Jongsoo JEONG, Noriyuki NISHIYAMA, Masaki KATAOKA, Kiyoshi SAITO, Suna ...
Article type: Article
Pages
33-34
Published: August 05, 2003
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A hybrid air conditioning system consists of a gas engine as a driving source and a hybrid refrigerator which can be driven by waste heat and motive power simultaneously. It can improve the efficiency of the gas engine heat pump greatly because it uses waste heat from the gas engine. This paper aims to estimate the performance of this hybrid air-conditioning system by the simulation. The objective hybrid refrigerator is composed of the single and double effect absorption type and the single-stage compression type refrigerator. The static simulation model of the hybrid air conditioning system is constructed and the performance is simulated using the model. As a result of the simulation, higher performance part load can be realized by changing the backup gas flow rate and hot water flow rate.
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Takuro SAKAMAKI, Masaharu KATO, Takumi HASHIZUME, Hirokazu YONEDA, Kat ...
Article type: Article
Pages
35-36
Published: August 05, 2003
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The purpose of this paper is to investigate the influence of the shortage of refrigerant amount relating to the refrigerating capacity and COP by analyzing two years' operating data of 40USRT Brine Chiller using CO_2. The shortage of refrigerant amount decreases refrigerating capacity because of inadequate condensation of refrigerant in gas cooler. In addition, it also decreases COP although CO_2 temperature at the gas cooler outlet is maintained to obtain maximum point of COP corresponding to compressor discharge. Therefore, retaining the appropriate refrigerant amount and controlling the discharge pressure of compressor give this system higher performance efficiently.
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Koji KUSANO, Akiharu OUSAKA, Mitsuru YOKOO, Hiroshi SOUMA, Masaya YANO
Article type: Article
Pages
37-38
Published: August 05, 2003
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On the artificial soil freezing, estimated the completion time and solidification layer thickness are greatly affected by many parameters, such as diameter/pitch of the pipe (s), temperature of the circulating brine, temperature and thermal properties of the soil as well as velocity of groundwater flow. In this paper, we numerically and experimentally examined the effect of these parameters on the freezing of artificial soil. The numerical results were good agreement with experimental ones. It was also shown that the thickness of the solidification layer is considerably influenced by the existence of flow rather than the velocity of flow. But the profile of the layer is still dominated by the velocity and direction of the flow.
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Takahiro URAGO, Toru SAWAI, Masuo KAJI
Article type: Article
Pages
39-40
Published: August 05, 2003
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The effect of surfactant on pressure drop and flow structure was investigated in vertical upward two-phase flow. Simultaneous measurements of spatio-temporal characteristics of liquid holdup and differential pressures were conducted in a 25.8mm i.d., 4.2m long acrylic pipe. The effectiveness of surfactant in reducing the pressure drop was observed. The pressure drop reduction (PDR) of up to 40% for slug flow and 15% for churn/annular flow was achieved. The PDR decreases with increasing the liquid volumetric flux for both flow regimes. The PDR in flow was caused by the reduction of the gravitational pressure drop. A decrease in wave frequency for annular flow was observed after the addition of surfactant, which made the fluctuation of the pressure gradient to be large.
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Jamshid POURESFANDAIRY CHAM, Shigeru HINATA, Nobuhiro HIMENO, Ichio IC ...
Article type: Article
Pages
41-42
Published: August 05, 2003
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A numerical analysis on the free convection heat transfer in a stably stratified fluid between vertical plates under the constant temperature wall is performed. A Galekin finite method is employed for the analysis of this double diffusive natural convection. Computations are carried out for the Prandtl number Pr=13.6,the Lewis number Le=333,an aspect ratio A=11.25,in the range of the Rayleigh number from 9.13x(10)^5 to 2.74x(10)^6 and for the various buoyancy ratios corresponding to the experimental condition in the previous report. The results of numerical analysis are compared with the experimental results and are discussed.
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Katsuhiro MATSUDA, Hirofumi HATTORI, Tomoya HOURA, Yasutaka NAGANO
Article type: Article
Pages
43-44
Published: August 05, 2003
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Direct numerical simulations (DNS) of a turbulent thermal boundary layer along a uniformly heated wall with zero pressure gradient has been conducted. The computational domain is composed of two parts : one is the driver part where the inflow boundary condition is constructed, and the other is the main simulation part. In the driver part, inflow conditions for the velocity field are generated by using the well-established universal velocity profile, and those for the thermal field are made in a similar manner. DNSs are carried out under two conditions, i.e., the Reynolds numbers based on the momentum thickness at the inlet are set at 300 and 600,and the Prandtl number is 0.71. The distributions of the friction coefficient and the Stanton number mimic very well the respective empirical laws. Moreover, the mean velocity and temperature profiles are simulated quite sufficiently, thus indicating that further discussion on the structure of turbulence is legitimate.
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Zhong ZHANG, Eiji TOMITA
Article type: Article
Pages
45-46
Published: August 05, 2003
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In this study, we first considered the influence of the measurement noise in LDV measurements, and tried to remove the noise using discrete wavelet transform (DWT). Then turbulent velocity in the combustion chamber measured by LDV was analyzed. The major results can be summary as follows : 1) The influence of the noise in the turbulent velocity becomes large as frequency increases. Therefore, a setup of cutoff frequency is difficult when removing the noise with a lowpass filter. 2) In this case, it is effective to remove the noise using DWT.
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Fumihito OHYA, Kazuie NISHIWAKI
Article type: Article
Pages
47-48
Published: August 05, 2003
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The scalar and velocity scale distributions in a steady round jet which is issued through a straight pipe nozzle at several Reynolds numbers were measured using laser light scattering image. Numerical simulations were also carried out with two-equation turbulence model and the results were compared with measurements. Discussions were made on model constants for integral length scales.
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Nobuyuki KAWAHARA, Eiji TOMITA, Daisuke FUKUDA
Article type: Article
Pages
49-50
Published: August 05, 2003
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In this study, the velocity fields near the nozzle exit of swirl injector spray for direct-injection gasoline engine was measured by using the PIV method. The image of liquid sheet velocity near the nozzle exit was enabled to be captured by PIV system with the long distance microscope and the double-frame CCD camera. Since the liquid sheet velocity was extremely fast, the measurement condition was optimized with changing interrogation area, pulse width, overlap, and so on. PIV images were obtained under the conditions of the injection pressure (5MPa) and two ambient pressures (0.1,0.5MPa). Consequently, the influence of the ambient pressure for the liquid sheet velocity was clarified. The main results obtained here are as follows. Increasing the ambient pressure reduces the liquid sheet velocity near the nozzle exit. The average of liquid sheet velocity under the steady state is 113 m/s when the ambient pressure is 0.1 MPa and about 71 m/s when the ambient pressure is 0.5 MPa.
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Norihisa ACHIHA, Shohei MIKAMI, Taku TSUJIMURA, Yoshiroh TOKUNAGA, Jir ...
Article type: Article
Pages
51-52
Published: August 05, 2003
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The jet expands outside the nozzle exit when the injection pressure is much larger than the ambient one. The jet flows as an underexpanded flow. The behavior of underexpanded jets injected into the atmospheric pressure ambient are well known. However there are few works about the flow at high pressure ambient. Therefore in this study, the jet flows near the nozzle exit have been observed with changing experimental conditions of injection, ambient gas, and nozzle configuration to clarify their effects on structures of underexpanded jets and on the jet developing process.
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Kwangjae MYONG, Motoyuki ARAI, Hirotaka SUZUKI, Jiro SENDA, Hajime FUJ ...
Article type: Article
Pages
53-54
Published: August 05, 2003
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In multi-component liquid fuel spray, droplet atomization is affected by difference in physical properties (i.e., liquid density, surface tension, kinematics viscosity, etc.) of each component. Especially vaporization process is dominated by mass fraction of mixed components and distillation curve (boiling point). And hence, droplet atomization and vaporization process of multi-component fuel is different from those of a single component fuel. In this study, diesel spray characteristics (i.e., liquid length) of multi-component fuel (3 components mixed fuel) were investigated using Mie-scattered light imaging. Experiment was conducted in various injection pressure (25Mpa∿112Mpa), ambient gas density (5kg/m^3∿20kg/m^3), ambient gas temperature (400K∿700K) and different fuel mass fraction. And the effect of fuel temperature (300K, 368K) was investigated in order to assess vaporization characteristics on cold starting and normal operating condition. Fuel was injected into constant volume vessel through a hole type nozzle. Used fuel contains i-octane (C_8H_<18>), n-dodecane (C_<12>H_<26>) and n-hexadecane (C_<16>H_<34>) which were selected as low-, middle- and high-boiling point fuel, respectively. Experimental results show that liquid length is decreased with increasing volatility fraction within the multi-component fuel.
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Keiya NISHIDA, Shinsuke NOMURA, Yuyin ZHANG, Tomoaki ITO
Article type: Article
Pages
55-56
Published: August 05, 2003
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Quantitative measurement of vapor and liquid phase concentration distributions in a D.I. Diesel spray, which was injected by a group-hole nozzle into the high-temperature and high-pressure nitrogen atmosphere in a constant volume vessel, was carried out by means of the ultraviolet-visible laser absorption-scattering (LAS) imaging technique. The group-hole nozzles, in which the minute holes are arranged at a minute interval, are one of the nozzle structures to control the mixture formation in the spray. It is expected that the group-hole nozzle spray has a smaller mean droplet size and enough tip penetration as compared with the spray injected by the single hole nozzle having the hole area equivalent to the group-hole. Spray and mixture formation characteristics of the group-hole nozzle were analyzed based on the LAS measurement.
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Hironobu UEKI, Masahiro ISHIDA, Masashi NAGANUMA, Daisaku SAKAGUCHI
Article type: Article
Pages
57-58
Published: August 05, 2003
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A laser 2-focus velocimeter with a semiconductor laser as the light source has been developed for the measurements of velocity and size of diesel fuel droplet. Laser beam was concentrated to a small measuring volume for the droplet measurement near the nozzle orifice exit. The effect of needle valve movement on the droplet was clearly seen at 2.5D downstream from the nozzle orifice exit. It is clarified that the droplet size under the transient lift conditon at the needle valve opening is smaller than that under the full lift conditon even if the injection velocity is lower. The velocity fluctuation perpendicular to the nozzle axis is found to be larger under the transient lift condition than under the full lift condition.
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Masahide TAKAGI, Yasuo MORIYOSHI
Article type: Article
Pages
59-60
Published: August 05, 2003
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Discrete droplet model (DDM) is widely used to calculate diesel sprays. In DDM, the spray tip penetration is usually underpredicted. The predicted D_<32> value is sometimes too small. Therefore, it is required to examine modeling of droplet breakup, collision and drag force. In this study, 'breakup time' was introduced into TAB model as a breakup onset condition. The effects of coefficient, K, and breakup time on the spray tip penetration, D_<32>, and spray shape are discussed. As a result, it was found that good agreement between the calculation and measurement could be attained by using different combined values of K and breakup time.
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Masaaki KUBO, Kaori ARAI, Akihiro SAKAKIDA, Akihiro IIYAMA
Article type: Article
Pages
61-62
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new design technique was applied to the swirl nozzles of direct-injection gasoline engines. This new technique is based on 3-dimensional Computational Fluid Dynamics (CFD) using volume of fluid (VOF) model. A new technique using particle image velocimetry (PIV) has also been useed to measure the spray at the exit of nozzle holes. This technique made it possible to ascertain the liquid film thickness which affects atomization characteristics. The calculated results showed relatively good agreement with the measured results. A conventional method, known as Tanasawa's equation, was also compared with the measured results and shown its accuracy.
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Motoyuki ABE, Yoshio OKAMOTO, Yuzo KADOMUKAI, Toru ISHIKAWA, Yoshiyuki ...
Article type: Article
Pages
63-64
Published: August 05, 2003
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In order to reduce fuel consumption and emission of direct injection gasoline engine, high atomization performance and controlling spray pattern in a fuel injector is required. Atomization performance has been achieved by using a swirler from our previous study. This paper describes a method to control spray pattern which swirl-type injector generates. An L-Step nozzle (L-cut orifice nozzle) which has developed by our previous study generates horse-shoe pattern spray which has rich and lean concentration region in horizontal section view. Correspondence between fuel flow with swirl and nozzle shape has been investigated. The mechanism of horse-shoe pattern generation can be described by geometrical relation between spray pattern and arrangement of L-cut step-wall. According to the investigation, the rich region and lean region can independently be controlled by means of arranging step-wall position and height.
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Mikiya ARAKI, Chengjun XU, Hiroyuki YAMAMOTO, Seiichi SHIGA, Hisao NAK ...
Article type: Article
Pages
65-66
Published: August 05, 2003
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This paper presents the possibility to improve atomization of a high-speed liquid jet by utilizing the effect of wall impingement and its mechanism. A simple nozzle with the diameter of 0.3 mm and the L/D ratio of 4 was used to inject water into atmospheric condition with the injection velocity up to 300 m/s. The liquid column was impinged on the end of stainless cylinders with the diameter of 1,3 and 10 mm. Sauter mean diameter (SMD) was measured by narrow-angle forward-scattering technique, and the liquid film velocity was measured by a phase Doppler anemometry. SMD produced by wall impingement was much less than that of free jet. Thus it was shown that wall impingement is effective to promote liquid atomization. It was further shown that SMD of wall impingement is determined by only the liquid film velocity and the impingement angle. The dependence of SMD on the liquid film velocity was compared with that of free jet and the atomization mechanism was discussed on the basis of these characteristic features.
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Jun HORIKOSHI, Hideshi YAMADA, Shigeru HAYASHI, Seiichi SHIGA, Mikiya ...
Article type: Article
Pages
67-68
Published: August 05, 2003
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This paper presents effects of impingement atomization on air-blast atomizer for jet engines. In current jet engines, so-called air-blast atomizer is widely used. Combining the wall impingement atomization with air-blast atomizer may give improvement of atomization. The air velocity was varied from 41 m/s to 92 m/s and the liquid injection pressure was form 0.5 MPa to 7.5 MPa. Since, in the previous study, it was shown that impingement point of the liquid influences S.M.D. (Sauter mean diameter), so impingement point was varied from 0.5 mm to 2.5 mm upstream from the lip. In case of 0.5 mm upstream from the lip, S.M.D. was 1/3 compared with 2.5 mm upstream from the lip.
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Hironori CHISAKA, Jingshun FU, Nobuo KURIHARA
Article type: Article
Pages
69-70
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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An electronic control throttle is equipped in gasoline spark-ignition engines to improve the response of intake-air control system. However, because there is a dead time in discrete combustion process with 4-stroke engine, it's difficult to make dynamic control, when lean/rich air fuel ratio transitions and engine torque fluctuate significantly, intake-air control delay becomes a hard problem. In this paper, for intake-air control to improve response of intake-air control, the Smith compensation and various kind of linear dynamic delay compensation are investigated. It is confirmed that control is efficient by simulation of idle speed control with modified air intake control.
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Kentaro GOTO, Akira IIJIMA, Noriyuki YAMADA, Kenji YAMADA, Koji YOSHID ...
Article type: Article
Pages
71-72
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this research, the effect of hot residual gas, resulting from the application of a certain level of internal EGR, on combustion was investigated using a two-cycle engine and gasoline as the test fuel. Measurements were made of the ion current, cylinder pressure and combustion chamber inner wall temperature. Data were measured and analyzed on SI (Spark-Ignition) operation and AI (Auto-Ignition) operation.
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Ryosuke NAGATA, Takuto MORINAGA, Koji YOSHIDA, Hideo SYOJI
Article type: Article
Pages
73-74
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper presents the results of experiments conducted with a 2-cycle engine that was the world's first such engine to comply with the 2000 California emissions regulations for small off-road engine adopted by the U.S state of in 2000. This engine is fitted with a scavenging passage that runs around the crankcase before the scavenging port. The aim of this research was to investigate how changes in the quantity of heat transferred to the fresh air as a result of varying the length of the scavenging passage would affect the state of combustion and exhaust gas composition.
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Tetsuya MURAYAMA, Hidenori KOSAKA, Tetsuya AIZAWA, Yukio MATSUI
Article type: Article
Pages
75-76
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this study, we conducted numerical cycle simulation of intake, combustion and exhaust processes in a diesel engine with variable valve actuation in order to investigate the effects of opening and closing timing of intake and exhaust valves on the gas component in a cylinder. The results show that intake air mass is governed mainly by the intake valve timing and EGR rate is governed mainly by the exhaust valve closing timing.
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Takeji KAWAZUMI, Yasuhiro MITSUISHI, Kazuie Nishiwaki
Article type: Article
Pages
77-78
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Flame behaviors in weak to moderate knocking were observed with a high-speed digital video camera in a tow-stroke cycle gasoline engine. A number of time series of flame images were analyzed, including normal propagating flame and auto-ignited flame in the eng-gas. The results show that the auto-ignition sites appear one after another in both the weak and moderate knock and that a difference in a knock intensity reflects a difference in time interval of the appearance of the auto-ignition sites. Though the auto-ignition sites develops like a normal propagating flame, the examination of the time rate of flame area increase reveals that the flame area increases much faster for the end-gas combustion than for the normal propagating flames.
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Tsuyoshi SUZUKI, Akihiro KAKISHIMA, Koji YOSHIDA, Hideo SHOJI
Article type: Article
Pages
79-80
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This study attempted to elucidate combustion conditions in a progression from normal combustion to knocking by analyzing the ion current and light emission intensity that occurred during this transition. With the aim of understanding the combustion states involved, the ion current was measured at two positions-the center zone and the end zone of the combustion chamber. Light emission spectroscopy was applied to examine preflame reactions that are observed prior to autoignition in the combustion process of hydrocarbon fuels. The results obtained by analyzing the experimental data made clear the relationship between the ion current and light emission during the transition from normal combustion to knocking operation.
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Hideyuki FURUMAYA, Jingshun FU, Nobuo KURIHARA
Article type: Article
Pages
81-82
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The knock control has been introduced widely with a gasoline spark-ignition engine control system. Detecting knock and controlling ignition timing to allow and engine to run at the knock threshold provides the best power and fuel economy. To avoid the delay of knock detection, a technique based on the wavelet transform to detect knock in one combustion cycle is proposed in this paper. The index of knock detection is gotten with the comparison of scale power spectrum of plural resonance modes at same crank angle. The results of 4-cylinder gasoline engine examination show that this technique is may provide practical utility for real time diagnostics of combustion.
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Masakazu OKAI, Michikata KONO
Article type: Article
Pages
83-84
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The effect of turbulence induced directly opposite-injection of a pre-mixed fuel in constant volume vessel on combustion property and NOx concentration was investigated. It was found from experimental results that the burning velocity was increased and NOx concentration was reduced by turbulence induced directly opposite-injection of a pre-mixed fuel
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Kenji MIYASHITA, Toshinori TAKEBUCHI, Tomoyasu AIHARA
Article type: Article
Pages
85-86
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Isooctane and normal-dodecane are ones of hydrocarbon fuel for an internal combustion engine. Unsteady motion of molecules at liquid-vapor interface and heat conduction phenomenon of nano-sized liquid in air are simulated by molecular dynamics method. Molecular dynamics method is to solute numerically classical equation of motion of atoms as N-body problems. Macroscopic and microscopic physical quantities are obtained from time series data of position and velocity of atoms by using statistical mechanics. Vaporization rate of isooctane was faster than that of normal-dodecane at 600K. Vaporization of hydrocarbon causes decline of internal energy of the simulation system because of latent heat. At NVT ensemble condition, however, the internal energy is supplied by temperature keeping method.
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Atsushi SAKAI, Hiroyuki TAKEYAMA, Hideyuki OGAWA, Noboru MIYAMOTO
Article type: Article
Pages
87-88
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The combustion and emissions in a PCCI engine with normal heptane + isooctane blend and with ordinary diesel fuel were compared to clarify the effect of lower distillation temperature fuels. The deterioration in thermal efficiency with advanced injection timing with ordinary diesel fuel can be eliminated with lower distillation temperature fuels while there is a little difference in THC and CO emissions. Lower distillation temperature fuel effectively reduces fuel adhering on the cylinder liner wall and prevents fuel dilution into lubricating oil even with early injection when fuel directly impinges the cylinder liner. Consequently, the thermal efficiency is improved with lower distillation temperature fuels, maintaining ultra low NOx.
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Hideyuki OGAWA, Noboru MIYAMOTO, Takao KAWABE, Wanchen Sun, Shigeru TO ...
Article type: Article
Pages
89-90
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In a small DI diesel engine, reducing the compression ratio to 16 is appropriate to reduce smoke emissions without deterioration of NOx and thermal efficiency. However, with a lower compression ratio, a low coolant temperature, or during the transient state following an increase in load, THC emissions significantly increase when using ordinary diesel fuel. In fully-warmed steady state operation with a compression ratio of 16 and diesel fuel, THC is reasonably low, but the level increases with lower coolant temperature or during the transient period just after increasing the load. This problem can be eliminated with a low distillation temperature fuel such as normal heptane. Benzene, butadiene, and other unregulated emissions also increase under the high THC conditions with the diesel fuel.
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Hirofumi NOGE, Campuzano Lopez, Yoshiyuki KIDOGUCHI, Kei MIWA
Article type: Article
Pages
91-92
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Thermal cracking and oxidization process of diesel fuel in an atmospheric pressure and high temperature place were investigated using flow reactor. When NO gas is introduced under oxidation condition of Solvent, NO is reduced upto 60% by thermal decomposed hydrocarbons. C_2H_4,which is main component of thermal cracking hydrocarbons, reduces NO upto 80%. According to the numerical simulation using CHEMKIN III, reduction mechanism of NO by thermal crackin hydrocarbon is depended on formation of HCCO and CH_2. In addition, C_2H_2 formation process plays an important role to produce HCCO and CH_2.
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Daisuke SHIMO, Motoshi KATAOKA, Hidefumi FUJIMOTO
Article type: Article
Pages
93-94
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The new NOx reduction method, "Expansive Vertical Vortex Combustion (EVVC)" was suggested as follows. A combustion expansive flow developed along the piston bowl can form a strong vertical vortex. This vortex can mix hot burned gas into the cold excess air existing in the center of the piston bowl, which gets burned gas coool rapidly. Therefore, it is possible to reduce NOx which would be produced if burned gas remained hot. In this paper the EVVC effect was verified by CFD analyses and experiments on a 4-cilinder 2.0-liter direct injection diesel engine. As a result, it was found that the EVVC was an effective method, because the stronger vertex could reduce NOx by over 20% without worsening smoke and thermal efficiency.
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