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論文
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SIGA, Seiichi ; 志賀, 聖一
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Departmental Bulletin Paper
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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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論文
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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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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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論文
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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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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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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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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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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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