• 한국가스학회지
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• 제17권3호
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• pp.8-13
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• 2013

이 논문의 목적은 LPG 자동차에서 연료누설에 의한 화재관련 사례에 대하여 연구하는 것이다. 첫 번째 사례는, 엔진의 연료 레귤레이터 및 인젝터 사이의 고압호스와 연결되는 연료 라인을 수리한 다음 고정하는 볼트를 규정토크로 조이지 않아 호스가 빠지면서 LP 가스가 누출되어 엔진의 열에 의해 화재가 발생한 것을 확인하였다. 두 번째 사례는, 인젝터를 교환한 다음 흡기매니폴드 유닛의 조립부에 삽입할 때 고정하는 고정부를 점검하지 않고 고정부가 변형되어 휜 상태에서 조립한 결과 연료의 누설을 방지하는 O링이 찢어져 이 사이로 연료가 누출된 것으로 확인되었다. 세 번째 사례는, 연료압력 조절기 유닛에는 연료 차단 솔레노이드 밸브가 연결되어 있는데 수리 후 이 연결 커넥터의 기밀작업을 철저하게 하지 않아서 미세하게 LP 가스가 누설되다가 어느 순간에 많은 양의 가스가 누설되면서 엔진의 열에 의해 화재가 발생된 것을 확인하였다. 따라서, 연료 시스템에 문제가 없는지 철저하게 관리하여 화재의 발생이 최소가 되도록 하여야 한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.7-8
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• 2006

The governing equations for high-speed lateral atomizing injector nozzle flow based on the LES-VOF model in conjunction with the CSF model are presented, and then an integrated parallel computation are performed to clarify the detailed atomization process of a high speed nozzle flow and to acquire data which is difficult to confirm by experiment such as atomization length, liquid core shapes, droplets size distributions, spray angle and droplets velocity profiles. According to the present analysis, it is found that the atomization rate and the droplets-gas two-phase flow characteristics are controlled by the turbulence perturbation upstream of the injector nozzle, hydrodynamic instabilities at the gas-liquid interface, shear stresses between liquid core and periphery of the jet. Furthermore, stable and a high-resolution computation can be attained in the high density ratio (pl/ pg = 554) conditions conditions by using our numerical method.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.99-106
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• 2010

A piezo-driven injector was applied with a purpose to evaluate the effect of induced voltage on spray characteristics. For this, injection rate, macroscopic imaging, ambient gas entrainment and particle sizing were carried out. It was shown that initial slope of injection rate was steeper as induced voltage increased, while slope of injection rate became mostly constant with fully opened needle. From macroscopoic imaging, longer spray tip penetration was produced with higher induced voltage. Moreover, wider spray angle was detected in the early stage of spray development, when higher induced voltage was applied. Ambient air entrainment rate was increased and particle size was reduced with higher induced voltage.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.13-18
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• 2010

본 연구는 Kerosene-LOx를 추진제로 하는 가스발생기용 스월 동축형 인젝터의 리세스 길이에 따른 내부 혼합 유동의 특성 파악을 목표로 하였다. 리세스 길이는 분무 안정성, 내부 LOx post 손상 등에 영향을 미치는 중요한 요소로 액막두께, 매니폴드 압력 측정 및 내부 유동 가시화를 통해 리세스의 영향을 분석하였고, 추진제 혼합 전후의 액막두께 변화를 측정함으로써 주파수 특성을 분석하였다.

• 한국분무공학회지
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• 제1권2호
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• pp.66-73
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• 1996

The present study investigates experimentally the characteristics of liquid jet, which is, the spray flow in the normal direction of the air stream under the flow conditions of air velocity $110\sim125m/s$. The present study adopts with the flow visualization technique using a short duration light bulb and the image processing analyse with CCD camera. Two types of injector were used: one is a flat plate type, and the other is backward facing step type, which height are 5, 8, 10mm. Dispersion of liquid jet can be represented by gray level of CCD camera. In the upstream of liquid jet, the backward facing step shows better liquid jet penetration. However, in the downstream. mean droplet size for backward facing step injector is smaller than that for flat plate injector

• 한국전산유체공학회지
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• 제11권2호
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• pp.40-48
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• 2006

In the present, The theoretical and numerical results of gas flow characteristics inside a swirl injector are presented. For this purpose a one-dimensional (theoretical) model and 2D/3D CFD models are proposed for use in the design of the injector. It was found that contradictory to the classical theory about the compressible flow, the swirl has a significant effect on the mass flow rate and the choking conditions. It was found that the one-dimensional model provides reasonably accurate results compared with the 2D/3D numerical results, and thus can be used at the initial stage of the swirl-injector design process.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.207-212
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• 2005

In this paper, we present the theoretical and numerical results of flow characteristics of a gas in a swirl injector. Proposed in this study are one-dimensional (theoretical) model and 2D/3D CFD models for use in the design of the injector. It was found that contrary to the classical theory about the compressible flow, the swirl gives a significant effect on the mass flow rate and the choking conditions. The one-dimensional model was found to Provide reasonably accurate results compared with the 2D/3D numerical results, so that it can be employed in th initial stage of the swirl-injector design process.

• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1194-1205
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• 2005

The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to a high pressure common-rail type fuel injection system for the control capability of the high pressure injector's needle and firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector's needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector, both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For the evaluation of the needle response of the above two injectors, we indirectly estimated the needle's behavior with an accelerometer and injection rate measurement employing Bosch's method was conducted. The experimental results show that the spray tip penetrations of piezo­driven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope in piezo-driven injector by altering the induced current.

• 한국추진공학회지
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• 제1권1호
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• pp.1-7
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• 1997

본 연구는 기체/액체를 사용하는 Swirl injector에 의해서 형성된 Spray fan 사이의 간섭효과를 평가하기 위한 실험연구로서, 공급압력과 인젝터 사이의 거리를 변수로 하여 실험을 수행하였다. 사용되는 기체는 공기, 액체는 물을 사용하였으며, 분사된 물의 질량분포를 채집하여 Spray fan의 간섭효과를 평가하였다. 본 연구 범위에서 실험결과는 다음과 같다. 액체만 공급하여 형성된 두 개의 Spray fan이 충돌할 경우, 충돌점 하부에 질량이 집중적으로 포집되었고, 공급압력이 증가함에 따라 이러한 간섭현상은 감소하였다. 공기와 물이 동시에 공급될 경우에도 충돌점 하부에 질량이 집중되는 현상을 나타냈으나, 공기압력대 물 압력비가 증가함에 따라 이러한 간섭현상은 감소하였다.

• 한국연소학회지
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• 제19권2호
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• pp.15-20
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• 2014

Environmental regulations are being reinforced for the solution of environmental pollution, that are global issues. Exhaust gas regulations of off-road engines also demand stepwise reduction emission from beginning of Tier 4 interim(2013). Characteristically, Tier 4 regulation apply the NRTC mode which is a transient cycle. And technical studies using NRTC mode are uncommon. In this study, for satisfy the Tier 4 final regulation on the NRTC mode, experimental study was conducted using a 3.4 L off-road engine. Fuel injection timing and injector hole number are chosen as parameters for investigation of combustion and exhaust gas characteristics on off-road diesel engine.