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森田, 真一 ; 渡辺, 直樹 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the direct EGR in the 2nd
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combustion process, NO emission could be expected to decrease. However, much Soot was exhausted by a weak mixing in the 2nd combustion process. A high pressure injection with a common rail was introduced into the engine to improve the mixing in the second combustion process. As a result, more NO was exhausted while Soot was decreased due to better mixing. In this study, to decrease NO and Soot simultaneously, two stage fuel injection was applied to the 1st combustion. When the main injection timing for the 1st combustion process was extremely delayed, NO and Soot were decreased. It was considered that NO reduction was due to the 1st combustion of low temperature and EGR effect in the 2nd combustion. Also, Soot reduction was due to a relatively long ignition delay for the 2nd combustion
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| 2.
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倉持, 大輔 ; 川口, 知宏 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinged on an extrude
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d wall, which was a top of cylindrical column, were experimentally investigated. Appearance positions of OH and C_2 radical luminosities and luminous flame kernel were stereoscopically observed using a two-way fiber optical system. The extruded column was fixed in a high temperature and high pressure combustion chamber. A diesel spray was impinged vertically to the extruded wall. Effects of cylindrical column diameter (D=5,10,15mm, ∞(flat wall)) on ignition and combustion characteristics were investigated. As the result, appearance position of OH luminosity was observed near the spray tip except for D=∞ (flat wall). The maximum volume of luminous flame impinged on the extruded wall was strongly influenced by the diameter of the column. In a condition of low-ambient temperature, the maximum volume of blue flame on the extruded column of 10 mm diameter was larger than those on other columns.
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| 3.
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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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| 4.
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川口, 知宏 ; 長瀧, 翼 ; 天谷, 賢児 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Ignition and combustion characteristics of diesel spray impinging on a wall were experimentally investigated. Ignition position and appearance position of the luminous flame
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kernel were stereoscopically observed using a two-way fiber optical system. Flat
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| 5.
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林, 義裕 ; 若林, 千裕 ; 古畑, 朋彦 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Mixture formation of diesel spray impinged on an extruded surface, which was a top of cylindrical column, was investigated experimentally. A diesel spray was impinged vertically to the
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extruded surface. The behaviors of impinged spray were observed using a high-speed drum camera. A spray volume was estimated from the photographs. Effect of cylindrical column diameter on spray behavior was investigated. Adhering fuel was measured by a primitive ""wiping by paper and mass measuring"" method under various conditions. Air-fuel ratio in spray was calculated from spray volume and adhering fuel. As the result, the behavior of diesel spray impinged on an extruded column was strongly influenced by the diameter of the extruded column. From the measured results, it is clear that the air-fuel ratio in spray in the extruded column diameter of 45mm was larger than those in the other columns.
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高, 炅男 ; 樅山, 智裕 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Diesel spray impinged normally on a flat wall was investigated. Spray tip penetration and spray volumes of before and after impingement were measured on high speed photographs of the sprays
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which were injected by a single shot injection system into a high pressure chamber of cold state. The effects of the spray tip penetration, spray volume, entrainment mass and air-fuel ratio were discussed on the sprays of before and after impingement. The volume of the post-impingement spray was calculated using axi-symmetrical model. It was greatly affected by the distance between the injection nozzle and the wall. When the impingement distance was shorter than the break-up length of the original spray, the entrainment mass as well as the volume of post-impingement spray was the larger than that of the original spray at the same inspection time. To calculate the average spray concentration of after impingement spray, the fuel film stuck on the wall was measured. The average air-fuel ratio of the impingement spray increased faster than the free spray because the spray concentration in a space decreased by the fuel stuck on the wall.
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| 7.
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斉藤, 正浩 ; 荻原, 五郎 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Behavior of spray-to spray impingement, where two spray jets were formed EFI (Electronic Fuel Injection) nozzles and impinged each other, was studied experimentally. This system was
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named MISS EFI. Spray penetration and the Sauter mean diameter of the spray were measured to investigate the effect of spray-to-spray impingement. When the impingement location was set at the vicinity of the nozzles, impingement phenomena became to be jet to jet impingement of the liquid column. In this condition, the penetration became shorter than that of the individual penetration. However, the penetration did not changed after spray-to-spray impingement. From the photographs of jet-to-jet impingement, it was confirmed that the liquid film was formed by the impingement, and then this liquid film disintegrated to small droplets. In the spray-to-spray impingement, on the other hand, the relatively large droplets still existed in the impinged spray, because the two sprays crossed each other without disintegration of the droplets. The photograph of the spray-to-spray impingement showed that the droplet-to-droplet impingement in the spray was rarely observed. Further, the chance of coagulation of the droplets was less observed than the disintegration of the dropled. These behavior of the spray-to-spray impingement agreed with the reduction of the Sauter mean diameter of the impinged spray.
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| 8.
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ISMAILOV, Murad ; DURST, Franz ; OBOKATA, Tomio
概要:
application/pdf<br />Journal Article<br />In the present study an LDA-based technique was applied to analyze details of
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a transient pipe-flow induced upstream by a fuel ingector. Due to highly accurate measurements of the instantaneous time series of velocity, fuel flow rate and pressure gradient were achieved. The pipe flow has been driven under an injection pressure of 0.6MPa at high injection frequencies of 25 and 50 Hz. The influence of the outflow orifice diameter, varid in range from 100 to 500 μm, on the transient pipe flow dynamics has also been described. The results show that transient behavior of rapid oscillating pipe flow is remarkably and systematically dependent on injection frequency and duration as well as on the orifice diameter.
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| 9.
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江原, 拓未 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />In this paper, behaviors of diesel spray injected along a wall were experimentally investigated. In order to clarify the wall effect on spray structure, the geometry of the wall and its
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relative position to the spray axis were varied. Structures of spray injected into a high-pressure atmosphere were recorded by high-speed photographs. Results shows that the asymmetrically large vortexes in the spray were induced by the wall effect, and the spray penetrating along the wall was deviated to the wall surface. This phenomenon is called the Coanda effect in the field of fluid dynamics. The growth orientation of spray was defined by image analysis. Maldistribution ratio of spray area was defined for the quantitative estimation of the spray deviation behavior. The spray deviating conditions such as the geometry of the wall and its relative position to the spray axis were fined.
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| 10.
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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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