• 한국수소및신에너지학회논문집
• /
• 제23권2호
• /
• pp.183-190
• /
• 2012

The research shows the experiment results according to the combustion characteristics and configuration of the linear generator of powerpack for the generating power applying the 2-stroke compact linear engine. The powerpack used in this paper consists of 2-stroke linear engine, linear generator and air compressor parts. For identifying the combustion characteristics and generating power of linear engine, some parameters were varied sucha as electric load, fuel input calorie, spark timing delay and equivalence ratio. Also generating power was confirmed at each operation conditions, when the air gap length of linear generator part was changed as each 1.0 mm and 2.0 mm. During the all operations, intake air was inputted under the wide open throttle. Mass flow rate of air and fuel was changed using mass flow controller, after these were premixed by premixture device, and then premixed gas was supplied directly into each cylinder. As a result, piston frequency and combustion characteristics were different at each conditions according to parameters affecting the combustion such as fuel input calorie, resistive load, spark timing delay and equivalence ratio. Consequently, these had an effect on generating power.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
• /
• pp.34-40
• /
• 2004

Two different type scramjet models with side-wall compression and top-wall compression inlets have been tested in HPTF (Hypersonic Propulsion Test Facility) under the experimental conditions of Mach number 5.8, total temperature 1700K, total pressure 4.5㎫ and mass flow rate 3.5kg/s. The liquid kerosene was used as main fuel for the scramjets. In order to get fast ignition in the combustor, a small amount of hydrogen was used as a pilot. A strut with alternative tail was employed for increasing the compression ratio and for mixing enhancement in the side-wall compression case. Recessed cavities were used as a flameholder for combustion stability. The combustion efficiency was estimated by one dimensional theory. The uniformity of the facility nozzle flow was verified by a scanning pitot rake. The experimental results showed that the kerosene fuel was successfully ignited and stable combustion was achieved for both scramjet models. However the thrusts were still less than the model drags due to the low combustion efficiencies.

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권7호
• /
• pp.1101-1110
• /
• 2004

An one-zone heat release analysis was applied to a 4 cylinder indirect injection diesel engine. The objective of the study is to calculate heat release accurately considering the effect of specific heat ratio. heat transfer and crevice model and to find out combustion characteristics of an indirect diesel engine considering the effect of the pressures in main and swirl chambers. Especially specific heat ratio indicating combustion characteristics is adapted. instead of that indicating matter properties, which has been used in former studies Moreover by adaption of blowby model, cylinder gas mass became accurately calculated. Therefore, with ideal gas equation, calculating cylinder gas temperature, it was found to affect heat transfer loss and heat release. Determining heat transfer constants $C_1$. $C_2$ as 0.6 respectively. the integrated gross heat release values were predicted well for the measured value at various engine speed, full load operating conditions. The curve of heat release rate was similar to SI engine rather than DI engine. That is originated from that swirl chamber reduce an instant combustion which occurs in DI engine due to ignition delay on early stage of combustion.

• 한국추진공학회지
• /
• 제17권6호
• /
• pp.1-10
• /
• 2013

본 연구에서는 다이아프램이 설치된 하이브리드 로켓 모터에서 발생하는 큰 압력진동의 가진 요인을 분석하였다. 다이아프램 유 무와 다이아프램 직경, 산화제 유량, 연료 길이 등의 다양한 실험조건을 고려하여 하이브리드 로켓 모터 추진시험을 수행하였고, 하이브리드 로켓 모터 가시화 장치를 이용하여 다이아프램이 삽입된 연소기의 내부 연소장을 가시화 하였다. 이러한 실험을 통해 주요 연소실 압력 가진 요인은 hole-tone인 것으로 판단되고, hole-tone 모델로 예측한 주파수와 추진 시험을 통해 획득한 주요 압력진동 주파수가 잘 일치함을 확인하였다.

• 한국추진공학회지
• /
• 제22권5호
• /
• pp.22-31
• /
• 2018

본 연구에서는 연소실 경계조건 변화에 따른 핀틀 노즐의 동특성을 파악하기 위해 수치해석을 수행하였다. 핀틀의 움직임을 모사하기 위해 노즐과 핀틀의 영역을 분리하여 격자를 생성하고 중첩격자기법을 사용하였다. 연소실의 경계조건은 일정질량유량과 추진제 연소속도 조건을 적용하여 결과를 비교하였다. 일정질량유량조건은 입구에 유입되는 질량유량을 정량적으로 변화시켜 연소실의 압력과 추력 특성을 파악하였다. 추진제 연소속도 조건은 연소실 압력에 의한 연소속도 식을 고려하였다. 추진제 연소속도 조건은 일정질량유량조건과는 다른 비선형적 유량변화를 나타내며, 작은 유량으로도 큰 연소실 압력변화를 가져온다.

• 항공우주기술
• /
• 제2권1호
• /
• pp.164-170
• /
• 2003

KSR-III 주 엔진에서 발생한 연소불안정 방지를 위한 필름 냉각방식의 내열재 배플을 장착한 확대비 5.04의 엔진의 40초 연소시험을 수행하였다. 시험 조건은 KRS-III 새로 설정한 설계점 조건으로 산화제 공급유량 42.04kg/sec, 연료공급 유량 17.96kg/s를 공급조건으로 설정하였다. 연소불안정을 방지하기 위해 필름 냉각방식의 내열재 배플을 장착한 EM#11호기 설계점 연소시험을 한 결과 설정 연소시간인 40초 동안 연소불안정이 발생하지 않았다.

• 한국연소학회지
• /
• 제3권2호
• /
• pp.1-11
• /
• 1998

Experimental investigation on flame spread of blended fuel droplet arrays has been conducted for droplet diameters of 1.0mm and 0.75mm using high-speed chemiluminescence images of OH radical. The flame spread rate is measured with blended fuel composition, droplet diameter, and droplet spacing. Flame spread is categorized into two: a continuous mode and an intermittent one. There exist a limit droplet spacing, above which flame does not spread, and a droplet spacing of maximum flame spread, which is closely related to flame diameter. It is seen that flame spread rate is mainly dependent upon the relative position of flame zone within a droplet spacing. In case of large droplet, the increase of % volume of Heptane induces the shift of limit droplet spacing to a larger spacing since volatile Heptane plays a role of an enhancer of flame spread rate. In case of small droplet, the increase of % volume of Heptane leads to the shift of limit droplet spacing to a smaller droplet spacing. This is so because of the delayed chemical reaction time by the rapid increase of mass flux of fuel vapor for small droplet.

• 대한기계학회논문집B
• /
• 제23권6호
• /
• pp.778-787
• /
• 1999

In this study, the autoignition process of liquid fuel, injected into hot and stagnant air in a 2-D axisymmetric confined cylindrical combustor, has been investigated. Eulerian-Lagrangian scheme was adopted to analyze the two-phase flow and combustion. The unsteady conservation equations were used to solve the transition of the gas field. Interactions between two phases were accounted by using the particle source in cell (PSI-Cell) model, which was used for detailed consideration of the finite rates of transports between phases. And infinite conduction model was adopted for the vaporization of droplets. The results have shown that the process of the autoignition consists of heating up of droplets, vaporization, mixing and ignition. The ignition criteria could be determined by the temporal variations of temperature, reaction rate and species mass fraction. And the effects of various parameters on ignition phenomena are examined. These have shown that the increasing the reaction rate and/or the vaporization rate can reduce the ignition delay time.

• 한국대기환경학회지
• /
• 제21권4호
• /
• pp.459-469
• /
• 2005

In recent years, concerns have been growing globally regarding greenhouse gases. Open burning of biomass causes emission of a number of greenhouse and other gases and substances. This paper studied an analysis on the characteristics of four types of biomass using duel type cone calorimeter. Cone calorimeter is widely used for assessing combustibility of materials in Europe. As a result, we evaluated several characteristics of biomass, such as heat released rate, smoke production rate, CO, $CO_2$ production and mass loss rate, and so on. $CO_2$ is currently responsible for over $60\%$ of the enhanced greenhouse effect, and may be the most important contributor to future. $CO_2$ production for biomass in the range of $1.74\~1.99kg/kg$ is similar to previous research conducted by Bhattacharya et al. (2002a).

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2524-2527
• /
• 2007

Solid propellant gas generators (SPGG) play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. For such a purpose, the propellants should burn with a relative low flame temperature and the combustion gas should not contain corrosive constituents such as chlorine compounds. In accordance with these requirements, stabilized AN-based propellants have been usually used as the most appropriate oxidizer for propellant compositions. However, the burning area of the propellant intends to increase to satisfy the required mass flux because of its low burning rate. Consequently the burning area incensement brings on the SPGG size augmentation. A flow restriction such as filters is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. The feasibility of the size reduction of SPGG by the employment of filters have been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with relatively high pressure loss coefficient.