• Title/Summary/Keyword: 분사지연

Search Result 73, Processing Time 0.033 seconds

A Study on the Spontaneous Ignition of the Fuel Injected into a Hot Air Stream - Additional Report: Utilization of Diesel Oil and Emulsified Fuel- (高溫空氣流 에 噴射한 噴霧 의 自然燃燒 에 관한 硏究 -속보 : 경유 및 유화핵연료 사용-)

  • 방중철;태전간랑
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.9 no.5
    • /
    • pp.627-637
    • /
    • 1985
  • The combustion process and the performance of a diesel engine are seriously affected by the ignition delay period of the fuel used. Some methods for improving the combustion process in the engine cylinder are to well match the strength of air swirl with the space of sprays in the cylinder, to blend an ignition improver in the fuel, to inject a small amount of auxiliary fuel prior to main injection and so on. Recently, the improvement of fuel economy and the reduction of exhaust smoke and NO have been successfully achieved by supplying diesel engines with emulsified fuel. However, it is very difficult to know real combustion mechanism under such special conditions, because of many factors affecting on the combustion process in practical reciprocating engine. In the present paper, the combustion processes of diesel fuel and emulsion fuel were tried to improve and to observe by making contact with various lean pre-mixtures in the hot air stream duct. This hot air stream method has an advantage that the spontaneous combustion process can be observed under a simplified condition.

The Effect of Cetane Number on Exhaust Emissions in Low-temperature Diesel Combustion (저온 디젤 연소에서 세탄가가 배기가스 특성에 미치는 영향)

  • Han, Man-Bae
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.19 no.6
    • /
    • pp.17-22
    • /
    • 2011
  • This study is to investigate the effect of the cetane number in ultra low sulfur diesel fuel on combustion characteristics and exhaust emissions at 1500 rpm and 2.6bar BMEP in low-temperature diesel combustion with 1.9L common rail direct injection diesel engine. Low-temperature diesel combustion was achieved by adopting external high EGR rate with the strategic injection control without modification of engine components. Test fuels are ultra low sulfur diesel fuel (sulfur less than 12 ppm) with two cetane numbers (CN), i.e., CN30 and CN55. For the CN30 fuel, as a start of injection (SOI) timing is retarded, the duration of an ignition delay was decreased while still longer than $20^{\circ}CA$ for all the SOI timings. In the meanwhile, the CN55 fuel showed that an ignition delay was monotonically extended as an SOI timing is retarded but much shorter than that of the CN30 fuel. The duration of combustion for both fuels was increased as an SOI timing is retarded. For the SOI timing for the minimum BSFC, the CN30 produced nearly zero PM much less than the CN55, while keeping the level of NOx and the fuel consumption similar to the CN55 fuel. However, the CN30 produced more THC and CO than the CN55 fuel, which may come from the longer ignition delay of CN30 to make fuel and air over-mixed.

Linear Stability Analysis of a Baffled Rocket Combustor (배플이 장착된 로켓 연소기의 선형 안정성 해석)

  • Lee, Soo Yong
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.22 no.3
    • /
    • pp.46-52
    • /
    • 2018
  • A simple Crocco's $n-{\tau}$ time delay model and linear analysis of fluid flow coupled with acoustics are combined to investigate the high frequency combustion instability in the combustion chamber of LOX/hydrocarbon engines. The partial differential equation of the velocity potential is separated into ordinary differential equations, and eigenvalues that correspond to tangential resonance modes in the cylindrical chamber are determined. A general solution is obtained by solving the differential equation in the axial direction, and boundary conditions at the injector face and nozzle entrance are applied in order to calculate the chamber admittance. Frequency analysis of the transfer function is used to evaluate the stability of system. Stability margin is determined from the system gain and phase angle for the desired frequency range of 1T mode. The chamber model with variable baffle length and configurations are also considered in order to enhance the 1T mode stability of the combustion chamber.

Effects of CNG Heating Value on Combustion Characteristics of a Diesel-CNG Dual-Fuel Engine (디젤-CNG 혼소엔진에서 CNG 발열량 변화가 연소 특성에 미치는 영향)

  • Kim, Yongrae;Jang, Hyeongjun;Lee, Janghee;Kim, Changgi
    • Journal of the Korean Institute of Gas
    • /
    • v.19 no.6
    • /
    • pp.28-33
    • /
    • 2015
  • In this study, a dual fuel engine fueled with natural gas and diesel was tested to investigate the effects of heating value variation of CNG fuel. CNG substitution rate which is defined as the ratio of CNG and diesel supplied in a heating value basis was fixed at 80%. The higher heating value was varied from $10,400kcal/Nm^3$ to $9,400kcal/Nm^3$ by mixing nitrogen gas with pure CNG and diesel fuel was injected at a fixed injection timing. The engine test results showed that thermal efficiency and power output were decreased as the heating value of mixed CNG fuel was decreased. And the peak cylinder pressure was also decreased but the ignition delay time and the combustion duration and timing were almost same.

Numerical Investigation of Dual Mode Ramjet Combustor Using Quasi 1-Dimensional Solver (근사 1차원 솔버를 이용한 이중모드 램제트 연소실 해석)

  • Yang, Jaehoon;Nam, Jaehyun;Kang, Sanghun;Yoh, Jai-ick
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.49 no.11
    • /
    • pp.909-917
    • /
    • 2021
  • In this work, a one-dimensional combustor solver was constructed for the scramjet control m odel. The governing equations for fluid flow, Arrhenius based combustion kinetics, and the inje ction model were implemented into the solver. In order to validate the solver, the zero-dimensi onal ignition delay problem and one-dimensional scramjet combustion problem were considered and showed that the solver successfully reproduced the results from the literature. Subsequentl y, a ramjet analysis algorithm under subsonic speed conditions was constructed, and a study o n the inlet Mach number of the combustor was carried out through the thermal choking locatio ns at ram conditions. In such conditions, a model for precombustion shock train analysis was i mplemented, and the algorithm for transition section analysis was introduced. In addition, in or der to determine the appropriateness of the ram mode analysis in the code, the occurrence of a n unstart was studied through the length of the pseudo-shock in the isolator. A performance a nalysis study was carried out according to the geometry of the combustor.

Emissions and Combustion Dynamics with Fuel Injection Position for Low-swirl Nozzles of Gas Turbine Combustor (복합발전 가스터빈 연소기용 저선회 노즐의 연료 분사 위치에 따른 배기배출 및 연소진동 특성)

  • Jeongjae, Hwang;Won June, Lee;Min Kuk, Kim;Han Seok, Kim
    • Journal of the Korean Institute of Gas
    • /
    • v.26 no.6
    • /
    • pp.37-44
    • /
    • 2022
  • In this study, two low-swirl nozzles with the same SN (Swirl Number) but different mass ratio (m) of the core part and the swirler part were designed to perform an atmospheric pressure combustion test. For each nozzle, a combustion test was conducted according to the adiabatic flame temperature, and the flame structure, emissions, and combustion instability mode were identified. Although the flame structure was significantly different, the CO emission was similar, and the NOx emission was also more related to combustion dynamics than the flame structure. Combustion dynamics and NOx emission were identified while adjusting the convection delay time by changing the position of the fuel injection nozzle. It was confirmed that when the convection delay time is in the region of (3+4n)/4T±1/4T (n=0,1,2,...), the combustion instability is strong, and in the opposite case, the combustion instability is very weak.

A Suggestion of Mix, Construction Method and Quality Control Criteria of Fine-size Exposed Aggregate PCC Pavement by Experimental Construction (시험시공을 통한 소입경 골재노출 콘크리트 포장의 배합, 시공 및 품질관리 기준 제안)

  • Lee, Seung-Woo;Kim, Young-Kyu;Choi, Don-Hwa;Shim, Jae-Won;Yoo, Tae-Seok
    • International Journal of Highway Engineering
    • /
    • v.13 no.3
    • /
    • pp.51-63
    • /
    • 2011
  • Surface of fine-size exposed aggregate portland cement concrete pavements(FS-EAPCC) is consist by exposed coarse aggregate to remove upper 2~3mm mortar of concrete slabs. Advantages of FS-EAPCC are maintaining low-noise and adequate skid-resistance level during the performance period. However, FS-EAPCC is required rational management criteria for field application, since it is early stage for application. Design construction and quality control criteria of FS-EAPCC was temporary laboratory tests which including optimum mix and exposing method, selection of adequate aggregate, resistance against, environmental loading and etc. However, these criteria need to be validated base on field application. In this study, experimental constructions were performed and construction procedure and quality control criteria were suggested based on the performance of the FS-EAPCC.

Analysis of the Actual Conditions of the Asphalt Regulations by Fire Service Organizations and Explosion Cases (아스팔트에 대한 소방기관의 규제 실태와 폭발사례의 분석)

  • Lee, Eui-Pyeong
    • Fire Science and Engineering
    • /
    • v.31 no.3
    • /
    • pp.97-105
    • /
    • 2017
  • Because asphalt is a solid at normal temperature and is not a hazardous material as stipulated in the Safety Management Act on Hazardous Materials, it is often recognized as having no risk of fire or explosion. On the other hand, it is as dangerous as flammable liquid because it is heated to $170-180^{\circ}C$ and stored in a storage tank. This study analyzed the risk of fire and explosion during the storage and handling of asphalt and the actual conditions of asphalt regulations by fire service organizations. Moreover, this study analyzed the domestic case of explosions in the production process of asphalt concrete (ASCON) and domestic and foreign cases of asphalt storage tank explosions. The analysis suggested that unlike Japan, Korea has no asphalt regulations in fire service organizations. Explosions can occur when ignition is delayed after fuel is sprayed on the dryer drum burner of the aggregates during the production of ASCON. A physical explosion can occur in the storage tank when environmental purification facilities suddenly work strongly to remove air pollutants or bad smells during the heating of asphalt in an asphalt storage tank. In addition, explosions can occur when fires such as welding is performed in the asphalt storage tank.

Study On The Development of Mobile Shampoo Device Using Ozone Water For Good hair condition (모발에 좋은 오존수를 이용한 이동식 샴푸 장치 개발에 관한 연구)

  • Kim, Duck-Sool
    • Journal of the Korean Applied Science and Technology
    • /
    • v.34 no.2
    • /
    • pp.394-399
    • /
    • 2017
  • The goal of this study is to suggest the technology and the way of developing ergonomic shampoo device, which is able to adjust the height and to be devided, and it uses ozone water. As a result of developing the device, it can complete better the effect of preventing water splash than existing devices by making neck holding part higher. And it is also made with ergonomic design, therefore, the head of shampoo candidate can be drawn into it more easily. By adjusting water temperature($38^{\circ}C$) to candidate's taste through water heater attached to water bucket, when a candidate is being shampooed, it can help keep warm shampooing without delaying. We could know the process through temperature sensor. And we could also know the utility of its own sterilization(1PPM) and purification. Finally, ozone water was measured for 20 minutes and the ozone concentration was measured to be less than 1 PPM to ensure stability. All parts of the mobile shampoo stand together with the hot water device and the ozonated water conversion device were designed so as not to be inconvenient for the user to use.

Preparation of Hydroxypropyl Methyl Cellulose with Controlled Solubility Rate by Surface Treatment Reaction (표면처리반응에 의한 용해속도조절용 Hydroxypropyl Methyl Cellulose의 제조)

  • Lee, Moo-Jin;Shin, Young-Jo
    • Applied Chemistry for Engineering
    • /
    • v.10 no.4
    • /
    • pp.581-585
    • /
    • 1999
  • The surface treated hydroxypropyl methylcellulose(HPMC) which could adjust the soluble time was synthesized when 40 wt % glyoxal solution and $KH_2PO_4$ were sprayed and reacted. And also, the solution dynamic at different ratios of two adding agents were identified If the surface of HPMC was treated with only glyoxal, the dispersion characteristics at different ratios of two adding agents were identified If the surface of HPMC was treated with only glyoxal, the dispersion was observed in the neutral solution and the viscosity was increased after directly dissolved as the solution become alkali condition. But the fine-powder type of HPMC which reacted with glyoxal and $KH_2PO_4$ was dispersed regardless of pH of solution and observed that it was dissolved and its viscosity increased after elapsing some time. With increasing amount of glyoxal and $KH_2PO_4$, the soluble time was delayed. The reaction condition was about 60 min at $75{\sim}85^{\circ}C$. Especially, the removal process of organic solvent after reaction was not required due to reaction under water solution without organic during glyoxal and $KH_2PO_4$ treatment. And also, the HPMC which could adjust the soluble rate in water or organic solvent by changing the degree of substitution of HPMC was synthesized.

  • PDF