분무 형상에 따른 디젤엔진 성능 특성 비교

우영민(Youngmin Woo),이영재(Youngjae Lee),김윤영(Yunyoung Kim),김종혁(Jong-Hyuk Kim),민병두(Byung-Du Min) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The characteristics of spray diesel injected into the cylinder provide crucial clues to the perception of the combustion performance in a compression ignition engine. In this study, five different diesel 커먼레일 injectors were examined which have different hole number, jet cone angle, and hydraulic flow rates. Both the macroscopic and microscopic characteristics of diesel sprays were compared through Mie-scattered light imaging and PDA (Phase-doppler anemometry) measurements. Seven hole injector with smaller hole was found to give better air/fuel mixing and favorable droplet size compared with other injectors. To evaluate the feasibility of achieving lower emission level with the different diesel sprays, the combustion and emission characteristics in case of 6 and 7 hole injectors were investigated under the same fuel flow rate condition in a light duty DI diesel Engine. The results showed that 7 hole injector with pilot injection had shorter combustion delay and combustion duration, but these effects were not found in high speed and high load condition with no pilot injection. The Seven hole injector could be utilized to achieve lower emission compared with six hole one because of more improved spatial distribution of fuel in combustion chamber. The full load performance such as brake torque and thermal efficiency of 6 and 7 hole injectors were slightly different according to engine speed.

CRDI 디젤엔진의 피에조 인젝터 불량에 따른 파형 분석에 관한 실험적 연구

유종식,김철수 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.6

This paper investigates the relationship of voltage and current waveform between normal piezo injector and deterioration abnormal piezo injector. The experimental methods using Pico oscilloscope and GDS scan tool are employed to measure current and voltage waveform and fuel pressure of piezo injector. The experiment is carried out during no-load condition. A summary of the important results are as follows. 1) In case of normal injector, the fluctuation of duration time of piezo injector was linearly and regularly decreased with increasing engine speed, but the that of deterioration piezo injector was irregularly decreased with increasing engine speed. 2) In main injection, the peak value of the current waveform of abnormal injector was larger than that of normal injector, the duration time of deteriorated abnormal injector was less than that of normal injector at 800rpm and 1500rpm, but the duration time of deteriorated abnormal injector was larger than that of normal injector at 2000rpm and 3000rpm. This irregularity appears to be caused by the deterioration of the injector.

Effects of Needle Response on Spray Characteristics In High Pressure Injector Driven by Piezo Actuator for Common-Rail Injection System

Lee Jin Wook,Min Kyoung Doug The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.5

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.

HC and CO emissions reduction by early injection strategy in a bioethanol blended diesel-fueled engine with a narrow angle injection system

Park, S.H.,Yoon, S.H.,Lee, C.S. Applied Science Publishers 2013 APPLIED ENERGY Vol.107 No.-

The main purpose of this study was to investigate how a narrow angle injector affects the combustion and exhaust emissions characteristics in a single-cylinder diesel engine fueled by diesel-bioethanol blends. This study focused on reducing HC and CO emissions in the exhaust emissions by the bioethanol blending of diesel. A narrow angle injector with an injection angle of 70<SUP>o</SUP> was used and compared with a conventional angle injector having a 156<SUP>o</SUP> injection angle. The bioethanol was blended with the conventional diesel up to 30% with 5% biodiesel. Experiments revealed that, in a narrow angle injector, the premixed combustion duration increased with bioethanol contents unlike the similar value of conventional injector. The premixed combustion phasing decreased with the increase of bioethanol in both injectors. The variation in the peak combustion pressure of the narrow angle injector was smaller than that of a conventional injector. In addition, the narrow angle injector induced a higher indicated mean effective pressure (IMEP) and a shorter ignition delay compared to the conventional injector. In terms of exhaust emissions characteristics, the low and stable ISHC and ISCO emissions can be achieved through the application of narrow angle injector to the diesel-bioethanol blends combustion. By the early injection combustion strategy, ISHC and ISCO emissions are significantly reduced.

BOSCH 솔레노이드 방식의 Grade 인젝터와 IQA 인젝터 불량이 연료 분사량제어에 미치는 영향에 관한 실험적 연구

강성구,김철수 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.3

In this paper, 'Pico scope' was used to measure and analyze high voltage waveforms of 'Grade injector' and 'IQA injector' due to defective solenoid injector of CRDI diesel engine, and the following conclusions were obtained. In the case of the injector of 'Grade Injector' and 'IQA Injector', there was no change in the injection timing of the injector while the injector was installed. However, by controlling the operation time, It is judged that the injector control is insufficiently controlled when the number of revolutions of the engine is increased to 2000 rpm and 3000 rpm in the idling state in the idling state because the injector failure is precisely controlled in the idling state, When determining the fault injector, the waveform of the 'Grade injector' and 'IQA injector' can be detected by waveform analysis by comparing the injection control time by measuring the high voltage waveform of the injector control in idle idling state. Can be easily diagnosed and maintained. I hope this study will be handed to the mechanics to make diagnosis of CRDI injector convenient.

구조해석을 통한 디젤 인젝터 부품설계

조민석(Minseok Jo),심재경(Jaekyung Shim),곽승우(Seungwoo Kwak),임득재(Deukjae Im),나병철(Byungchul Na) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2

Diesel fuel injectors work by transferring fuel from the supply line to the fuel injector device which is attached to each cylinder where it is pressurized and then sprayed through a small nozzle into the cylinder"s combustion chamber. While a diesel fuel injector working, the highly pressurized fuel inside the fuel passage can cause the stress and deformation of parts of the injector and by extension, it may be a cause of malfunction of the injector. In this paper, the stress distribution and deformation of a 2,000bar diesel fuel injector model2 are analyzed using finite element method and compared with model1 for suggestion of better design.

커먼레일 디젤인젝터의 분사성능 개선을 위한 내부유로형상 최적화에 관한 수치적 연구

문성준(Seongjoon Moon),정수진(Soojin Jeong),이상인(Sangin Lee),김태훈(Taehun Kim) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.2

The common-rail injectors are the most critical component of the CRDI diesel engines that dominantly affect engine performances through high pressure injection with exact control. Thus, from now on the advanced combustion technologies for common-rail diesel injection engine require high performance fuel injectors. Accordingly, the previous studies on the numerical and experimental analysis of the diesel injector have focused on a optimum geometry to induce proper injection rate. In this study, computational predictions of performance of the diesel injector have been performed to evaluate internal flow characteristics for various needle lift and the spray pattern at the nozzle exit. To our knowledge, three-dimensional computational fluid dynamics (CFD) model of the internal flow passage of an entire injector duct including injection and return routes has never been studied. In this study, major design parameters concerning internal routes in the injector are optimized by using a CFD analysis and Response Surface Method (RSM). The computational prediction of the internal flow characteristics of the common-rail diesel injector was carried out by using STAR-CCM+7.06 code. In this work, computations were carried out under the assumption that the internal flow passage is a steady-state condition at the maximum needle lift. The design parameters are optimized by using the L16 orthogonal array and polynomial regression, local-approximation characteristics of RSM. Meanwhile, the optimum values are confirmed to be valid in 95% confidence and 5% significance level through analysis of variance (ANOVA). In addition, optimal design and prototype design were confirmed by calculating the injection quantities, resulting in the improvement of the injection performance by more than 54%.

노후 기계식 인젝터의 분무특성 연구

정민욱 ( Minuk Jeong ),유영수 ( Young Soo Yu ),양승호 ( Seungho Yang ),최민후 ( Minhoo Choi ),박성욱 ( Sungwook Park ) 한국분무공학회 2021 한국액체미립화학회지 Vol.26 No.3

Deteriorated agricultural diesel engines using mechanical fuel injection systems have low fuel injection pressures. And they are not equipped with an exhaust gas abatement device, so it produces a lot of exhaust gas. Remanufactured used injectors can reduce emissions because spray characteristics are improved. In addition, remanufacturing is environmentally friendly and economical compared to producing new parts. For efficient injector remanufacturing, it is necessary to conduct a comparison experiment on the spray characteristics of an used mechanical injector and a new injector of the same model. In this study, the spray characteristics of the two injectors were compared by performing an injection quantity measurement and a spray visualization experiment. As a result, the used injector had a larger injection quantity, a shorter spray tip penetration, a wider spray angle and a smaller spray area than the new injector.

3차원 CFD 상세 유로모델을 이용한 커먼레일 디젤인젝터의 내부 유동특성 분석

정수진(Soojin Jeong),문성준(Seongjoon Moon),이상인(Sangin Lee),김태훈(Taehun Kim) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5

Advanced combustion technologies for common-rail diesel injection engines require high performance fuel injectors. Therefore, computational predictions of the diesel injector performance have been performed to evaluate internal flow characteristics on the needle lift and the spray pattern at the nozzle exit. However, when the injector is in operations, only some flow driven out of the injector by pressure drop at the nozzle exit, the others flow is returned to fuel supply lines through a spool valve for needle lift control. Actually, the internal flow passage of an entire injector duct including injection and return routes has never been adopted for three-dimensional computational fluid dynamics(CFD) analysis. In this study, the computational prediction of the internal flow characteristics of the entire injector duct in the common-rail diesel injector is carried out by using STAR-CCM+ 7.04 code. For this, computations were carried out under the assumption that the internal flow passage is a steady-state condition at the maximum needle lift. The results show that pressure and velocity profiles of the this model, we found that the very thin flow passages appear a pressure drop and velocity increase. In particular, the study focuses on the uniformity index due to flow rate deviation between the needle entrance and the nozzle exit.

Effects of different piezo-acting mechanism on two-stage fuel injection and CI combustion in a CRDi engine

Jin-Su Kim,Juwan Kim,Seokcheol Jeong,Sangilk Han,이진욱 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12

In this study, the effects of two piezo injectors operated by different mechanisms on multi-injection and Compression ignition (CI) combustion were investigated. High-pressure injectors for CI engines are divided into two categories according to the actuator: Solenoid and piezo injectors. It is commonly known that both injectors have a hydraulic circuit for fuel injection; thus, the performance of the injector is highly dependent on not only hydraulic characteristics such as volume of internal chambers and nozzle geometry, but also the actuation mechanism. Specially, the direct needle-Driven piezo injector (DPI) is introduced in this study and compared with the indirectacting Piezo injector (PI) to investigate the injection characteristics and influences on CI combustion performance by using spray visualization, injection rate measurement, and single cylinder diesel engine experiments, as well as numerical simulation for injection rate modeling of DPI. In the spray visualization experiment, a high-speed camera was used to examine spray tip penetration length and spray speed with respect to each injector. Also, in order to investigate injection rate information, which is a significantly dominant factor in combustion characteristics, the Bosch-tube method was adapted under the condition of a back pressure of 4.5 MPa, corresponding to engine motoring pressure. Also, a single-cylinder CRDi (Common-rail direct-injection) engine experiment was carried out to determine the effects of different piezo-acting mechanisms on two-stage fuel injection and CI combustion. From the key results obtained by this study, the direct needle-driven piezo injector has a faster SOI (Start of injection) and EOI (End of injection). In addition, the overall shape of the injection rate of DPI was narrow and the injection had a higher spray speed than that of PI. Also, DPI has a higher heat release rate and peak pressure, as verified by the engine experiment. In particular, it was found that DPI showed the possibility of combustion improvement when applying a pilot injection strategy.