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| 1.
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椎名, 亮介 ; 荒木, 幹也 ; CHEN, Lai ; 中村, 壽雄 ; 志賀, 聖一 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />This paper presents basic combustion characteristics of a spark-ignition engine fuelled with three kinds of gaseous fuels; H_2, CO and CH_4. A single-cylinder engine was operated under WOT at
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1500min^<-1> condition. CO gas gives lower thermal efficiency than H_2 and CH_4, since the energy of the fuel can not be transferred to the pressure or the work, although it gives higher combustion temperature which makes the higher exhaust gas temperature and much higher NO_x emissions than those for CH_4. H_2 gives upper limit of flammability due to the occurrence of backfire and almost comparable thermal efficiency with that for CH_4 at its stoichiometric condition.
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| 2.
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椎名, 亮介 ; 荒木, 幹也 ; CHEN, Lai ; 中村, 壽雄 ; 志賀, 聖一 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />This paper presents basic combustion characteristics of a spark-ignition engine fuelled with three kinds of gaseous fuels; H_2, CO and CH_4. A single-cylinder engine was operated under WOT at
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1500min^<-1> condition. CO gas gives lower thermal efficiency than H_2 and CH_4, since the energy of the fuel can not be transferred to the pressure or the work, although it gives higher combustion temperature which makes the higher exhaust gas temperature and much higher NO_x emissions than those for CH_4. H_2 gives upper limit of flammability due to the occurrence of backfire and almost comparable thermal efficiency with that for CH_4 at its stoichiometric condition.
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| 3.
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田村, 貴洋 ; 荒木, 幹也 ; 山田, 秀志 ; 志賀, 聖一 ; 林, 茂 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Droplet size and spray dispersion characteristics of an impingement jet type jet engine fuel injector are investigated experimentally. The fuel injector is consisted of a pintle,
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intermediate ring, and outer ring, forming co-axial air flow channels with co-swirlers. Compressed air at room temperature is supplied with a blower, and is injected into the atmosphere through the co-axial channels. Distilled water is supplied with a liquid pump, and is injected from hole nozzles mounted in the pintle. The number of nozzles is 8 and 16. The liquid jets impinge onto impingement walls mounted on the intermediate ring, forming a free liquid film. From the tip of the liquid film, fine droplets are formed. The droplet size is measured using an LDSA, and the spray cross section is visualized using time-average Mie scattering method. It is shown that the droplet size is almost the same as the atomization of a simple wall impingement jet, which is much smaller than that for a conventional air-blast fuel injector, and it is observed that a relatively uniform spray is formed using the fuel injector.
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| 4.
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田村, 貴洋 ; 荒木, 幹也 ; 山田, 秀志 ; 志賀, 聖一 ; 林, 茂 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Droplet size and spray dispersion characteristics of an impingement jet type jet engine fuel injector are investigated experimentally. The fuel injector is consisted of a pintle,
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intermediate ring, and outer ring, forming co-axial air flow channels with co-swirlers. Compressed air at room temperature is supplied with a blower, and is injected into the atmosphere through the co-axial channels. Distilled water is supplied with a liquid pump, and is injected from hole nozzles mounted in the pintle. The number of nozzles is 8 and 16. The liquid jets impinge onto impingement walls mounted on the intermediate ring, forming a free liquid film. From the tip of the liquid film, fine droplets are formed. The droplet size is measured using an LDSA, and the spray cross section is visualized using time-average Mie scattering method. It is shown that the droplet size is almost the same as the atomization of a simple wall impingement jet, which is much smaller than that for a conventional air-blast fuel injector, and it is observed that a relatively uniform spray is formed using the fuel injector.
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| 5.
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荒木, 幹也 ; 小保方, 富夫 ; 石間, 経章 ; 増渕, 匡彦
概要:
application/pdf<br />Journal Article<br />Effects of fuel atomization on cold starting of a 4 stroke cycle spark ignitio
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n engine were investigated experimentally. Two kinds of ultrasonic fuel injectors using a micro nozzle array (MNA injectors) were applied, whose nozzle diameter d=4 and 6μm, respectively. A conventional port fuel injector (PFI injector) was also used for comparison. The Sauter mean diameters (SMDs) of the sprays were 15μm (MNA, d=μm), 23μm (MNA, d=6μm), and 59μm (PFI), respectively. An air cooled, single cylinder, 4 stroke cycle, spark ignition engine was used. The first ignition cycles and the cumulative fuel amount were investigated at a wide range of the air fuel ratio. For the MNA injector (d=4μm), the first ignition cycle became much earlier when compared with the PFI injector. The cumulative fuel amount during cold starting reduced by about 30%. It is shown that, by use of the MNA injector, the unburned hydrocarbon emissions during cold starting could be reduced.
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| 6.
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荒木, 幹也 ; 岸本, 秀雄 ; 中島, 邦明 ; 前原, 充宏 ; 志賀, 聖一 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Performance of a 2 stroke cycle engine fuelled with CNG (Compressed natural ga
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s) using intermittent fuel injection from a scavenging port is investigated experimentally. The test engine is a 2 cylinder, 398 cm^3, 2 stroke cycle spark ignition engine. Gaseous fuel injectors are attached at the cylinder block, and a CNG is injected into the scavenging passage through a fuel injection pipe. The fuel injection pressure is set at 0.255 MPa, and the fuel is injected intermittently during the scavenging process. The length and tip geometry of the fuel injection pipe are varied, and the effect on the engine performance is investigated. Using the scavenging port fuel injection, the BSFC is reduced by 25%, and the lean burn limit extends from λ = 1.2 to 1.46, at the maximum. The peak of the NO_x emission shifts to leaner side, and the THC emission is reduced by 47% at the maximum. It is considered that the intermittent fuel injection from a scavenging port is effective to achieve stratified combustion and reduction in fuel short circuiting through the cylinder.
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| 7.
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荒木, 幹也 ; 藤原, 康裕 ; 志賀, 聖一 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Accuracy of an injection rate measurement of a gaseous fuel injector was improved by modification of equations and static pressure correction. A production gaseous fuel injector for an NGV
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(Natural gas vehicle) was used, which is for an intake port fuel injection. The injection pressure was set at 255 kPa (g), and the injection duration was varied from 5 to 20 ms. Nitrogen gas was used as the test gas. The test gas was injected into a pipe from the injector, and the static pressure history was acquired with a piezoelectronic pressure transducer. One-dimensional, compressible, inviscid, adiabatic flow was assumed, and the instantaneous mass flow rate inside the pipe was estimated using newly modified equations. The pressure gradient due to pipe friction was corrected using Darcy-Weisbach equation. By integrating the injection rate during the injection duration, the total amount of mass flow per one stroke was calculated. The data obtained by the injection rate meter are compared to that of the calibration test, and it is shown that the injection rate measurement was carried out within the error of 2 to 3%.
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| 8.
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荒木, 幹也 ; 藤原, 康裕 ; 志賀, 聖一 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Injection rate of a gaseous fuel injector was calculated by measuring the needle valve lift history. In our lab, a gaseous fuel injection rate meter using 1-dimensional pipe flow was developed.
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In the present study, the measurement accuracy of the injection rate meter was examined by comparing the theoretical injection rate estimated from the needle valve lift history. The needle valve lift was measured using an optical method. A small beam cut plate is attached to the needle valve of the gaseous fuel injector. A laser beam passes through the beam cut plate, and the variation of the beam intensity was measured with a photo sensor. From the beam intensity, the needle valve lift history was estimated. One-dimensional, compressible, inviscid, adiabatic flow was assumed, and the instantaneous mass flow rate through the needle valve sheet, the injector sack, and the injection hole was estimated. The estimated injection rate was compared with that obtained with the gaseous fuel injection rate meter. The estimated and measured injection rates agree relatively well even at transient duration. It is shown that the injection rate meter has high reliability and accuracy.
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| 9.
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荒木, 幹也 ; 曽根, 祐輔 ; 小島, 孝之 ; 志賀, 聖一 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Supersonic jet noise was visualized using a newly developed optical CT (Computed Tomography) method. From a converging round nozzle whose exit diameter is 8.0 mm, air is injected into the
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atmosphere. The pressure ratio is set at 2.25 (M_j=1.14), and an under-expanded jet is formed. A sound wave is pressure fluctuation, and the density fluctuates at the same time, Using a kind of schlieren method, the fluctuation of the density gradient is detected. A He-Ne laser beam passes through the supersonic jej, and the beam direction is slightly refracted due to the density gradient inside and around the supersonic jet. The beam refraction is converted to a brightness signal using a knife edge and a photo sensor. The signal obtained with the photo sensor is the integrated value along the laser beam path. Using a modified Abel inversion, the local refraction of the laser beam is calculated and the tomogram is re-constructed. It is shown that, using the optical CT method, nonintrusive acoustic measurement is possible even inside the supersonic jet. It is shown that the sound source of the screech tone exists around the 4th shock cell of the under-expanded jet, and that intensive fluctuation is observed not only in the shear layer but also along the center axis of the jet, implying the existence of the traveling shock wave.
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| 10.
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小林, 義幸 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />An experimental study on an intermittent fuel spray initiated from a swirl injector proposed for direct injection spark ignition (DISI) engines has been carried out in order to clarify
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the effects of back pressure and ambient temperature. The measurements have been made in a constant volume chamber in which maximum pressure and temperature reach 1.1MPa and 423K, respectively. Visualization of the spray is performed by a high speed CCD video camera with laser sheet technique. Droplet velocity and diameter are acquired by phase Doppler anemometry (PDA), and processed by a time-dividing method which divides the phase matched spray information into five distinct periods. The effects of ambient temperature on the droplet velocity appear at the tip of the spray. The decrease in Sauter mean diameter D_<32> is observed at core region of the sprays when the ambient temperature is high conditions under both back pressures.
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| 11.
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荒木, 幹也 ; 小保方, 富夫 ; 石間, 経章 ; 志賀, 聖一 ; 増渕, 匡彦 ; 杉本, 知士郎
概要:
application/pdf<br />Journal Article<br />Effects of horn geometry on the atomization characteristics of an ultrasonic f
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uel injector using a micro nozzle array were investigated experimentally. Micro nozzles whose exit diameter d=3μm are mounted on a thin metal film. The number of the micro nozzles is from 2.0×10^4 to 1.2×10^5. Using an ultrasonic oscillator, gasoline is periodically pushed out from the micro nozzles at a frequency from 62 to 65kHz. A disk type PZT is used as an ultrasonic oscillator, and the oscillation is amplified using a step-type horn. The input voltage to the PZT is varied from 0 to 200V. To increase the fuel flow rate, the horn small end diameter Ds is increased from 10.5 to 25mm, while the large end diameter is fixed at 30mm. To prevent forming a liquid film on the micro nozzle array, gutters are machined on the small end of the horn. It is shown that the SMD (Sauter mean diameter) of the spray is almost uniform around 10 to 14μm, regardless of the horn small end diameter. The fuel flow rate increases, at the maximum, 2.8 times larger when compared to the original horn geometry.
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| 12.
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馬場, 泰一 ; 種市, 雄吾 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />To reduce friction loss in automotive reciprocating engine, it is required to
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know the lubricant oil film behavior. In the present study, a laser-induced fluorescence (LIF) and a particle image velocimetry (PIV) were applied to measure the oil film thickness and its velocity, independently. A model engine with a quartz glass cylinder was used. Using Rhodamine B, a linear relationship between oil film thickness and fluorescence intensity can be obtained in the range of 0 to 150μm. The LIF measurements were performed under the 300 rpm of mortaring condition. The range of oil film thickness was from 10 to 25 μm on the piston rings. The crank angle variation of oil film thickness was demonstrated successfully. The PIV measurements were also carried out under the motoring speed of 100 rpm. The velocity vector map was obtained in the slit of piston ring. The oil velocity was almost the same as the piston speed near the oil ring. Velocity profiles in the slit were visualized according to the crank angle positions. The results suggested the possibility to analyze the oil film behavior under the combination of the LIF and the PIV measurements.
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| 13.
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荒木, 幹也 ; 藤原, 康裕 ; 志賀, 聖一 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Injection rate measurement of a gaseous fuel injector was carried out by use of one-dimensional pipe flow. A production gaseous fuel injector for an NGV (Natural gas vehicle) was used,
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which is for an intake port fuel injection. The injection pressure was set at 255 kPa, and the injection duration was varied from 3.4 to 20 ms. Nitrogen gas was used as the test gas. The test gas was injected into a pipe from the injector, and the static pressure history was acquired with a piezoelectronic pressure transducer. One-dimensional, compressible, inviscid, adiabatic flow was assumed, and the instantaneous mass flow rate inside the pipe was estimated. By integrating the injection rate during the injection duration, the total amount of mass flow per one stroke was calculated. Caliburation test was carried out by use of a pressure vessel, from which the total mass flow during one stroke was estimated. Both data are compared, and it is shown that the injection rate measurement was carried out with an error of about 10%.
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| 14.
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荒木, 幹也 ; 新井, 正明 ; 岡本, 光司 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Velocity measurement of an intermittent high-speed flow inside a micro wave ro
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tor cell was carried out by utilizing a laser Doppler anemometry (LDA). The cell is 3×3mm rectangular tube, whose length is 42mm. The pressure ratio and rotor speed of the wave rotor were set at 2.5 and 5000rpm, respectively. Ethanol droplets were seeded into the flow as scattering particles. By use of laser beam expanders, the beam intersection volume of the LDA optics was minimized, and submillimeter spatial resolution is realized while a wide velocity range (-100 to 300m/s) is kept. It is shown that the velocity histories at local positions inside the wave rotor cell can be obtained with the LDA optics. The rapid velocity increase and decrease, due to the primary and secondary shock waves, are observed, and the propagation speed of the primary shock wave was estimated. It is shown that the spatial distribution of the maximum velocity inside the cell is constant, and that the boundary layer thickness inside the cell is smaller than 0.5mm. It is shown that the effect of viscosity is relatively small in such a micro wave rotor.
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| 15.
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荒木, 幹也 ; 堀越, 順 ; 山田, 秀志 ; 志賀, 聖一 ; 林, 茂 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Effects of a wall impingement jet on atomization characteristics of a jet engine fuel injector were investigated experimentally. Liquid is injected from 0.2mm-diam nozzles and the liquid
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columns impinge onto a wall. The liquid forms thin films on the impingement wall and fine droplets can be produced. Several kinds of impingement wall geometries, such as slope, parallel and cylinder types, were examined and the droplet size and atomization mode were investigated. The droplet size was measured with an LDSA. For the slope type, two kinds of atomization mode, namely, ""air blast atomization"" and ""pressure atomization"" modes were observed. The pressure atomization mode is preferable, since it leads to the atomization improvement of a jet engine in low load operations. For parallel types, the atomization characteristics were similar to that for the slope type. For cylinder types, pressure atomization mode can be realized with a small liquid injection pressure. And the droplet size in the pressure atomization mode is smaller when compared with the parallel types.
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| 16.
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荒木, 幹也 ; 桑原, 孝輔 ; 新井, 正明 ; 石間, 経章 ; 志賀, 聖一 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Effects of gas injection from a nozzle wall on screech reduction of a supersonic under expanded jet are investigated experimentally. From a converging round nozzle, air is injected into the
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atmosphere (Main jet) at a pressure ratio of 2.25 (M=1.14). The exit diameter of the main jet nozzle is 8.0mm. From small nozzles mounted in the main jet nozzle wall, air is injected in the normal direction to the main jet (Secondary jet). The exit diameter of the secondary nozzles is 1.0mm. The number of the secondary nozzles is selected to be 2 or 4, and the mass flow rate of each secondary jet is set at 2.0% or 4.0% of the main jet. With the secondary jets, the screech SPL is reduced by 23 dB at the maximum, and the frequency profile of the broadband noise is also influenced. And with the secondary jets, the total pressure of the main jet is slightly decreased with the increase in the total mass flow rate of the secondary jets. Consequently, it is shown that the gas injection method is effective in screech reduction with a small loss in the total pressure.
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| 17.
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高橋, 易資 ; 野村, 友和 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />A computational fluid dynamics (CFD) code with partial cells in Cartesian coor
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dinate (PCC) method has been developed. The merit of this method is that input data preparation time is extremely short because computational mesh data are separated from geometry data. However, a general Cartesian coordinate method has a big subject in calculation accuracy. One of the factors is precision in geometry expression around the complicated shape, and another is a turbulence model near the wall because mesh is independent from the boundary and not fitted with it. Therefore, discretization equations were derived based on Finite Volumetric Method, and a combination of the wall function and a low Reynolds number k-ε turbulence model was proposed here. This paper describes implementation of this method and shows the results compared with experimental data by particle image velocimetry (PIV) at the steady flow in the cylinder of a 4-valves S.I. engine. The comparison results of velocity vector maps show good agreement between CFD and PIV.
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| 18.
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山田, 秀志 ; 松本, 裕 ; 林, 茂 ; 志賀, 聖一 ; 荒木, 幹也 ; 堀越, 順 ; 中村, 壽雄 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />The effect of pressure atomization with wall impingement on the atomization characteristics was examined in a real scale jet engine burner. The air velocity was set from 41 to 92m/s, and the
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liquid injection pressure was from 0.5 to 7.5MPa. Two laser faci
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| 19.
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西川, 剛弘 ; 種市, 雄吾 ; 西川, 弘 ; 小保方, 富夫 ; 石間, 経章
概要:
application/pdf<br />Journal Article<br />Characteristics of the multistage high-pressure reciprocating compressor, which is expected to obtain outlet pressure over 30MPa have been studied. For the performance improving, it was
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tried to reduce the gas leakage at the compression parts and to raise the suction pressure. In order to raise the suction pressure, a double acting mechanism was developed at the first stage where two serial compression rooms were arranged. And for improvement of volumetric efficiency, the gas flow resistances at suction passage were decreased and the pressure pulsation effect due to rotation direction of compressor was changed at the suction-discharge pipe system. These flows are analyzed and improved by the experiments and numerical calculations.
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| 20.
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野村, 友和 ; 高橋, 易資 ; 武田, 親士 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Characteristics of the flow inside an engine cylinder model have been evaluated by a particle image velocimetry (PIV) and a laser Doppler anemometer (LDA). Verifications of the results by Partial
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Cells in Cartesian coordinate method numerical simulation have been also made by the experiment results. The model engine head that has two intake valves and transparent cylinder are used in the steady state flow condition. The tests are conducted by single- and dual- valve open condition with 8mm valve lift in-1470 Pa suction gauge pressure. The comparisons between the PIV and the LDA experiments show almost the same tendencies for mean velocities and turbulence intensities in the whole experimental regien qualitatively and also quantitatively. The differences in the valve open condition are clearly observed in the integral length and time scales that are estimated from the PIV and LDA data respectively. It is shown that the PIV results are useful for verification of numerical results, which agree reasonably with those of experiments.
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| 21.
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野村, 友和 ; 高橋, 易資 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />Boundary layer flow over a multi-holed plate is analyzed in this paper. Two perforated plates which have different diameter of holes and a flat plate are tested in the rectangular duct. The
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diameters of holes are 20mm or 40mm in staggered arrangement and the all plates are 10mm in thickness. These studies are carried out by means of two-dimensional LDA (laser Doppler anemometer) and numerical simulation with Partial Cell method. The mean flow velocity and the relative turbulence intensity are 4.5m/s and 2% respectively in both the experiment and the calculation. Comparisons of flows over the three plates are made for the mean velocity, turbulence intensity and Reynolds stress. In addition, the difference in turbulence flow structure depending on the diameter of holes has been discussed by experimental results.
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| 22.
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野村, 友和 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />Spatial correlation measurements of velocity fluctuations in turbulent flow over a rectangular cube are presented. Direct measurement of spatial correlation requires simultaneous measurement of
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velocities at two or multi-points in the flow. Therefore this study is carried out by means of a particle image velocimetry (PIV) or two LDAs (laser Doppler anemometer) composed by He-Ne and Ar^+ lasers. The cube is set on the floor of the wind tunnel. At the inlet, the mean flow velocity and the relative turbulence intensity are 4.0m/s and 1.5%, respectively in both experiments. Under this condition, the flow Reynolds number based on the rectangular cube height and the mean velocity is about 8800. Firstly, comparisons are made for longitudinal and transversal spatial correlation coefficients measured by LDA. Secondly, distributions of integral length scales distributions acquired by LDA and PIV have been discussed. In addition, the validities of integral length scale calculated by Taylor's hypothesis are evaluated in the flow.
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| 23.
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石間, 経章 ; 中村, 晋 ; 助名, 亮一 ; 小保方, 富夫 ; 河内, 勝義 ; 小林, 一光
概要:
application/pdf<br />Journal Article<br />An LDA flow rate meter which is based on the LDA (Laser Doppler anemometer) te
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chnique has been developed. The principle of the LDA flow rate meter applied for circular pipe is following. The center line velocity of pulsating pipe flow was measured by the LDA. The velocity distribution profile in the pipe cross section can be numerically estimated, and then the instantaneous flow rate was calculated by the integration of the profile. Firstly, it was applied and evaluated at the pulsating flow made by an artificial heat-lung system. The system has a double roller pump with a vinyl tube of Ω-shape. Secondly, an intermittent flow rate at high fuel pressure injection system was also measured. Swirl injector generated the oscillating pipe flow under high line pressure of 5 MPa at injection frequencies of 20 and 40 Hz. There was a little difficulty at the measurement of injection flow depending on the zero velocity shifting. Finally, a correction method of zero shifting was proposed and the applicability of the flow rate meter was demonstrated.
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| 24.
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石間, 経章 ; 助名, 亮一 ; 小保方, 富夫 ; 河内, 勝義 ; 小林, 一光
概要:
application/pdf<br />Journal Article<br />Characteristics of spray injected from the five types of swirl nozzle, which were the same design however differed in the static flow rates as 600, 700, 800, 900 and 1 000 cc/min respectively, have
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been evaluated by a phase Doppler anemometer (PDA) and a
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| 25.
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西川, 剛弘 ; 西川, 弘 ; 小保方, 富夫 ; 石間, 経章
概要:
application/pdf<br />Journal Article<br />Characteristics of the multistage high pressure reciprocating compressor, which expects to obtain outlet pressure over 30 MPa, have been studied. For improvement of volumetric efficiency, the
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performance characteristics are comprehensively studied by comparing the numerical results with those of experiments. These measures of pressure pulsation, valve dynamic behaviors and flow rate have been executed by experiment. Using the numerical simulation code of STAR-CD, which assumed three dimensional, compressible and unsteady flow, the dynamic phenomena of compressor parts has been demonstrated. Consequently, parameters that need for improvement of flows in the compressor have been discussed.
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| 26.
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高橋, 易資 ; 野村, 友和 ; 石間, 経章 ; 小保方, 富夫
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application/pdf<br />Journal Article<br />The PCC (Partial Cells in Cartesian coordinate) method CFD code featured with
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less pre-processing time was used in this study to calculate the flow field around a rectangular cube. The turbulence model was consisted using a low Reynolds number κ-ε model and log law. To test the case of existence of many partial cells, the rectangular cube was set with 10 degrees of offset angle to the flow direction, and calculation mesh does not correspond to the cube surface. The mean flow velocity and turbulence intensity were set to 4.0 m/s and 1.5%, respectively in both experiment and calculation. The experiments were carried out by using two-dimensional laser Doppler anemometry (LDA) and particle image velocimetry (PIV). The numerical results were compared with the experimental results. Both results show good agreement between calculation and experiment in the mean velocity, turbulence intensity and Reynolds stress.
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| 27.
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石間, 経章 ; ヨゼフ, イスマイル M ; 小保方, 富夫
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application/pdf<br />Journal Article<br />Particle laden water jet have been analyzed by means of a laser Doppler anemom
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eter (LDA). Glass spheres of 389μm in mean diameter were loaded into the injection water by a particle mixer and after then injected into still water bath. The particle/water jet injectors were made by brass pipes of which diameters were 5 and 8 mm. The mean velocities of the center of the jet were set as 1.8 and 1.5 m/s for 5 and 8 mm pipes, respectively. The initial volume fraction was set as 0.087% in all experiments. The results of vertical relative velocity between particle and water indicate that the particles have same velocity as water at the outlet of the jet however particle velocities are larger than that of water at the expanded jet in downstream. From the results of the transverse relative velocity, it is considered that the particle can get larger velocity than water at a certain downstream from the outlet. These features are well explained by using local Stokes number defined by local time scale of the turbulence and particle time constant as well as Saffman's lift force.
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| 28.
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周, 斌 ; Machacon, H.T.C. ; 志賀, 聖一 ; 譚, 達明 ; 柄澤, 隆夫 ; 小保方, 富夫 ; 中村, 寿雄
概要:
application/pdf<br />Journal Article<br />In this study a neural network prediction method that can be used in predicting engine behavior is proposed. Using data from a series of characteristic experiments, this method eliminates
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the need for complicated mathematical calculations used in prediction models. To test this method exhaust emissions and engine performance data from intake gas composition variation experiments were taken and compared with the predicted data from this network. The method has been tested and found effective in predicting engine exhaust emissions and engine performance. This technique can be a valuable tool in engine research.
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| 29.
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小保方, 富夫
概要:
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| 30.
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隆, 武強 ; 石間, 経章 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />To study the characteristics of velocity in a large-angle conical spray proposed for a premixed combustion type Diesel engine, steady and unsteady conical sprays were analyzed using a laser
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Doppler anemometer (LDA). The injection pressure for the steady conical spray was varied in three steps. For the unsteady conical spray, it was 19.6MPa, where the amount of injected fuel was 25.6mg per cycle, and the injection frequency was 20.7Hz. As a result, the radial distributions of mean axial-velocity for both conical sprays were similar to the Goertler distribution. The Shapes of the turbulence intensity distributions of the conical sprays and a radial gas jet were similar. Their values for the steady conical spray were smaller than that for the radial gas jet, and those for the unsteady conical spray were almost the same as that for the radial gas jet in the whole experimental region. The Reynolds stress distributions for the steady conical spray and the radial gas jet were similar but the maximum value of steady conical spray was half that of the radial gas jet. The unsteady conical spray had a value of the same order of magnitude as that of radial gas jet in the whole experimental region. The rate of decrease of the unsteady conical spray velocity was 3 times that of the steady conical spray velocity but 1/6 that of the radial gas jet velocity. The rate of air entrainment into the unsteady conical spray was half that for the steady conical spray.
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| 31.
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武田, 親士 ; 太田, 祐司 ; 石間, 経章 ; 石井, 清 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />In order to measure flow velocity in the swirl and radial directions of a cylinder of an engine in practical use by means of a laser Doppler anemometer (LDA) through a small measuring window on
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the cylinder head, a back-scattering fringe mode LDA is used. It, however, could not measure the velocity component in the axial direction of the cylinder. The single incidence-beam reference-mode LDA is developed to measure the velocity component along the optical axis of the LDA and applied to measure the fluctuating flow velocity in the axial direction of the cylinder. Ensemble-averaged mean velocity and fluctuation intensity of the velocity as measured by the LDA show good agreement with those measured by the conventional fringe-mode LDA. Based on these results, it can be concluded the reference-mode LDA is applicable to measurements of the flow velocity in the axial direction of the cylinder through the small window on the cylinder head.
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| 32.
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石間, 経章 ; 小山, 哲司 ; 田中, 秀昭 ; 小保方, 富夫 ; 真下, 亨 ; 小林, 一光
概要:
application/pdf<br />Journal Article<br />The characteristics of flow and particle diameters in the unsteady spray from
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an air-assisted fuel injector in atmospheric conditions have been analyzed using a phase Doppler anemometer (PDA). The frequency of injection was 50 Hz, and the pressures of both fuel and air were changed in three steps. Radial and axial distributions of bulk velocity and Sauter mean diameter of spray particles were obtained. It is found from the experiments that the profile of mean velocity is closely related to the normal distribution and the Sauter mean diameter of droplets in the spray is as small as 20 to 30μm. And the log-hyperbolic function (LHF3) has also been applied to the spray. Consequently, the characteristics of the distribution of spray particle sizes are represented clearly by the three parameters of the LHF3.
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| 33.
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隆, 武強 ; 大塚, 博行 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />To study the characteristics of flow and particle diameters in large-angle con
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ical spray proposed for Diesel engines of premixed combustion, unsteady conical spray in the air has been analyzed using a phase Doppler anemometer (PDA). In experiments, the frequency of injction is 20.8 Hz and the amount of injection fuel is 10.3 mg in each cycle. Axial and radial distributions of bulk velocity and mean diameter of particles are obtained. As a result, it is found that the profile of mean velocity distribution is close to the Goertler distribution, and the Sauter mean diameter of droplets in the conical spray is as small as 30μm. Correlation between particle diameter and velocity in the entire spray is negative and unusual, but is found to be normal if the spray is divided into parts and studied. We also find that particles with small diameter (20μm) which are emitted at high speed (60m/s) at the earliest stage lose velocity rapidly, merge into bigger particles, and are overtaken by bigger but slower particles which are emitted at the later stage. Particles with large diameter (50μm) gather at the tip of the spray as they travel farther from the nozzle exit.
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| 34.
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細谷, 肇 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />There have been many experiments to characterize Diesel fuel spray under steady-state conditions. However, the appropriate number of holes and the hole position on the sac to be used in the
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experiment are not clear. To address this subject, we investigate Diesel type spray flows using a laser Doppler anemometer (LDA) and a phase Doppler anemometer (PDA). Spray flow characteristics such as mean and fluctuating two-component velocities, two-dimensional distribution of particle diameter and the variation of three parameters at the log-hyperbolic fitting for particle size distribution are given from measured data. Spray jets from four varieties of Diesel nozzle are compared with each other to clarity the differences in spray characteristics between them. The results show that the spray from the single-hole nozzle on top of the sac is distinct from the others.
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| 35.
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小保方, 富夫 ; 橋本, 徹 ; 五十木, 慎一 ; 柄沢, 隆夫 ; 志賀, 聖一 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The swirl and axial components of gas velocity in the disk-type combustion cha
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mber of a firing engine were measured by an LDA. The engine was operated under the conditions of a speed of 1500rpm, η_υ=0.5, φ=1.4 and ignition timing of 30°BTDC. The gas velocities at 9 points on a diameter at midheight of the combustion chamber were analyzed by the cycle-resolved method. The bulk (mean) velocity was determined by the frequency discrimination method with the cut-off frequency of 667Hz. The flame propagation pattern was detected by ionization probes set at 17 points on the piston. It has been observed that, in the case of fired operation, the turbulence intensity is higher, the integral length and micro length scales are longer and the swirl flow is weaker and is eccentrically shifted compared with the case of motored operation. These results show that it should be noted that there are remarkable differences in the gas flow between motored operation and fired opeation.
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| 36.
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細谷, 肇 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />Diesel fuel spray from a single-hole-type injection nozzle is investigated under steady and atmospheric conditions in order to understand the unsteady Diesel spray. Axial and radial
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velocity components of the spray at two constant injection pressures of 9.8MPa and 4.9MPa are measured by laser Doppler anemometer (LDA), and turbulence characteristics of the spray flow velocities are analyzed. Distributions of mean velocity and turbulence characteristics in the spray flow are compared with gas jets and other spray flows. It is found that the injected spray is accelerated in the region close to the nozzle exit, and this phenomenon may be estimated as a kind of cavitation caused by expansion of dissolved gas in the fuel. The decrease in centerline velocity along the nozzle axis is very small and the air entrainment factor is also shown to take a smaller value than in previous experiments.
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| 37.
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小保方, 富夫 ; Bopp, Stefan ; Tropea, Cam
概要:
application/pdf<br />Journal Article<br />A simple adapter for a two-dimensional, backscatter, fiber-optic laser Droppler anemometer probe consisting of two glass plates has been developed to measure the spatial
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correlation of velocity fluctuations. A conventional two-color, four-beam LDA probe has been modified by reversing the placement of two of the fibers so that both the green and the blue control volumes measure the same velocity component. An adapter for beam separation is ten mounted behind the front lens to separate the two control volumes. In the present work, the measuring point separation was varied up to 3 mm in the lateral and vertical directions. By using only one glass plate 10 mm thick, it was also possible to achieve in-line (Axial) displacements of the control volumes of up to 3.5 mm. spatial correlations were performed in an intermittent jet flow in which the convective flow velocity could be deduced from the offset of the cross-correlation function.
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| 38.
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小保方, 富夫 ; 柄沢, 隆夫 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The bulk velocity and turbulence of air swirl flow in the dish type combustion
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chamber of a motored engine were measured by an LDA. The LDA was modified with optical finers for easy operation and was improved to form a smaller measuring space 0.29 mm in length. The engine was operated at a speed of 1 000 rpm. The gas velocity at a mid section of the combustion chamber was analyzed by the stationary time average method. The radial distribution of mean swirl flow and turbulence characteristics such as turbulence intensity (u'), integral time and spacial scale (L_t, L) and micro time and spatial acale (λ_t, λ) were obtained, and time depending properties of such flow data were investigated. It has been revealed that the mean swirl velocity and swirl ratio almost agree with those of previous reports, but u' is higher and scales of turblence are lower than the data given by the hot-wire anemometer.
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| 39.
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小保方, 富夫 ; 花田, 尚喜 ; 桑原, 秀樹 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The velocity and turbulence in two-dimensional wedge type engine combustion chambers are measured by a laser Doppler anemometer (LDA) with an optical fiber transmitting system under motored
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and firing conditions. The engine is operated at a speed of 2 500 rpm with propane-air mixtures changing the combustion chamber setting direction to the cylinder, here named normal ""N"" and reverse ""R"" combustion chambers. The preliminary experiment indicates that the flame propagating velocity near the slant ceiling and the indicated mean effective pressure are of a higher level at the R chamber than at the N chamber. The mean velocity U^^-, fluctuation intensity u' and integral time scale of turbulent L_t in both chambers are derived through the stationary time averaged analysis of the measured velocities, and each is compared between both chambers. The results have showed that the flow patterns in both chambers are different and the mean value of the U^^- of the R chamber at the spark timing is large than the other by about 70%. However there is little difference at u' and L_t in both chambers.
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| 40.
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小保方, 富夫 ; 花田, 尚喜 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />The intensity and structure of turbulence in a flame front may be changed by expansion flow due to combustion. Therefore the velocity and turbulence in a combustion chamber of a spark
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ignition engine are measured by mans of a laser Doppler anemometer with fiber-optic pick-up under firing conditions. The engine is operated at a speed of 2500 rpm with propane-air mixtures. Data acquisition window width affects the turbulence intensity (u') and integral time scale of turbulence (Lt) of the analysis. In the experiment, a short (0.67 ms) and long (4 ms) window are selected and compared with each other. In the combustion period, twice the intensity of u' and an increase of 40 % in Lt are observed in the case of short window analysis. A stronger u' and larger Lt are observed in the long window analysis and it is shown that the Lt expands laterally during the compression stroke and vertically during the expansion stroke.
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| 41.
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小保方, 富夫 ; 花田, 尚喜 ; 倉林, 俊雄
概要:
application/pdf<br />Journal Article<br />To improve the adaptability of LDA (laser Doppler anemometer) for measuring velocities in an engine, an optical fiber system composed of a couple of single mode, polarization-preserving
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optical fibers has been made to transmit the incident beams. Though the total transmitting efficiency of this optical system is about 24 %, it has been confirmed that a fiber-optic LDA system with a 25 mW He-Ne laser is applicable to the real-time measurement of gas velocity in the combustion chamber of a small-sized two-stroke spark ignition engine. The ensemble-averaged mean velocities obtained by using this optical system show that the gas velocity rapidly decreases just before the flame front arrival and suddenly increases after passing of the flame. It is also shown that a new bulk flow is generated in the chamber by the gas expansion due to combustion.
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| 42.
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小保方, 富夫 ; 松尾, 典孝 ; 平野, 嘉男
概要:
application/pdf<br />Journal Article<br />ピストン・リード弁付きクランク室圧縮形二サイクル機関の流れをレーザ流速計で実時間測定した.その結果,交換窓や回転窓の使用が不可欠であることがわかった.また,
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実機の吸気流および排気流は駆動と発火時によりかなり異なったパターンを示すが,掃気流ではあまり差異はない.さらに機関を一連の管系におきかえ,特性曲線法を用いたシミュレーションで求めた駆動と発火時の各管内流は実測値とよく一致した.
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| 43.
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小保方, 富夫 ; 浅沼, 強
概要:
application/pdf<br />Journal Article<br />火花点火機関の低公害・省エネルギ燃焼を実現するために燃焼室内のガス流動が利用されている. このガス流動を発火運転中までも含めて実測するためのレーザ流速計シス
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テムを完成させ, ±80m/s以上の変動流や強いサイクル変動のある燃焼流と実時間で測定した. 副室からのトーチ噴流に及ぼす副室容積, ノズル径, 当量比, 回転数の影響を調べ, トーチ開口割合が大きいと複数の噴流, 逆流があるなど, 流速計の実機適用の可能性を示した.
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| 44.
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浅沼, 強 ; 小保方, 富夫
概要:
application/pdf<br />Journal Article<br />レーザ・ドップラ流速計は、原理的に被測定流体の圧力や温度にほとんど影響されないため、発火運転時をも含め、シリンダ内の非定常な流れを、実測し得るものと期待され
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る。よって、まずレーザ・ドップラ流速計を用いてシリンダ内ガス流動を実時間で連続測定するために必要な実験条件を明らかにし、ついで供試機関につき、駆動および発火運転時におけるシリンダ内スキッシュ流を実測した結果、その有用なことが明らかとなった。
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