• 한국세라믹학회지
• /
• 제30권12호
• /
• pp.1096-1102
• /
• 1993

Titanium nitride was synthesized by reacting Ti powder with nitrogen gas using SHS method. In this process, the effects of nitrogen pressure, dilution with TiN, or additiion of titanium hydride(TiH1.924) on the conversion of Ti to TiN were investigated. In particular, much effects were given to solve the problem of the conversion drop due to partial melting and subsequent sintering of Ti parciels, by controlling combustion temperature and combustion wave velocity via mixing Ti powder with TiN or/and TiH1.924. For the diluted titanium powders with TiN, the conversion close to 100% was resulted when the nitrogen pressure was over 8atm and with diluent content of 60wt%, and the self-propagating reaction was not sustained when the diluent content was higher than 60wt%. For samples mixed to be 55wt% in Ti component in the mixture of Ti, TiH1.924, and 45% TiN, the conversion was closed to 100% when the amount of titanium hydride added was over 7wt% and the nitrogen pressure was higher than 5atm. The combustion reaction, however, was not sustained when titanium hydride added was more than 10wt%.

• 한국연소학회지
• /
• 제22권1호
• /
• pp.8-13
• /
• 2017

Ignition delay time of methane/oxygen mixture is measured experimentally with the shock tube in order to obtain the data for high pressure conditions where gas turbines and internal combustion engines are operating. The shock tube experiment is validated first over the temperature range of 1400-2000 K at 10 bar and with the various equivalence ratios of 0.5, 1 and 2. The measured ignition delays are compared with the data from the literatures. And then, experiments are conducted for non-explored conditions, i.e., at 40 bar and with the equivalence ratio of 1.5. The present experimental data show a good agreement with the available ones from the literatures and reasonable dependence on pressure and equivalence ratio. In addition, the effects of the temperature and equivalence ratio on ignition delay time are analyzed.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년도 제31회 추계학술대회논문집
• /
• pp.326-329
• /
• 2008

DARPA가 계획 중인 대형 극초음속 추진 기관 개발 프로그램 VULCAN 프로그램은 듀얼모드 램제트/스크램제트 엔진과 연계되어 TBCC엔진을 이룰 수 있도록, 기존의 터보제트(또는 터보팬) 엔진과 CVC과 엔진을 결합하여 마하수 4이상에서 작동 가능한 엔진을 개발하는 것을 목표로 하고 있다. CVC 엔진은 데토네이션 연소 현상을 기본으로 하여 고마하수에서 고효율을 얻을 수 있는 PDE 이나 CDE와 같은 신개념의 엔진이다. 본 논문에서는 부산대학교 항공우주공학과 연소 추진 연구실에서 지난 수년간 국제공동 연구의 형태로 수행한 데토네이션 현상의 추진기관 응용에 연구에 대하여 소개한다.

• 한국세라믹학회지
• /
• 제27권1호
• /
• pp.118-126
• /
• 1990

Titanium Cabride powders were prepared by the self-propagating high temperature synthesismethod in air from the mixture of metal titanium powder and carbon powder. The result are as follows : 1. The conversion effciency of higher than 95% can be obtained and the lattice constant value of the product was 4.322$\AA$. 2. The combustion mode, velocity and temperature of combustion wave was photographed using high-speed camera, and showed steady-state, velocity of 15.414mm/sec at 250$0^{\circ}C$. 3. The relative density and MOR strength of TiC sintered at 180$0^{\circ}C$ for 90 minutes by hot-pressing under the pressure of 200kg/$\textrm{cm}^2$ were 95% and 395MPa, respectively.

• 한국연소학회지
• /
• 제4권1호
• /
• pp.59-65
• /
• 1999

Ignition of $NH_3-O_2-Ar$ mixtures have been studied behind reflected shock waves over the temperature range of 1600-2300 K and the pressures in the range of 1.1-1.6 atm. The pressure profile and the radiation emitted behind the shock waves have been monitored to give empirical correlations between ignition delay times and the mixture concentrations with the experimental conditions. On the basis of this data, several kinetic mechanisms proposed for ammonia oxidation at high temperatures have been tested. The ignition delay times obtained from the mechanism proposed by Miller and Smook were in good agreement with our experimental results.

• 한국연소학회지
• /
• 제8권2호
• /
• pp.41-49
• /
• 2003

Ultrasonic field of 28kHz with sound pressure level 162dB has been employed to agglomerate the fine soot particle produces in a diffusion flame in a chamber. The agglomeration process has been investigated with digital camcorder and analysed in terms of the decrease of number density with exposure time. From the observation of agglomeration process, the initial agglomeration has been carried out during the short time, and it has been dominated by the orthokinetic collision. Thereafter, a slower agglomeration mechanism, driven by acoustic streaming in the chamber takes over and agglomeraters grew to diameters of several millimeters were levitated at the pressure node of the acoustic wave. And, the circular disk shape of large agglomeraters with the rotational and translational motion is observed.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.574-579
• /
• 2003

The present study addresses an analytical investigation to understand the characteristics of gas flow in the High-Velocity Oxy-Fuel(HVOF) thermal spray gun. One-dimensional analysis is extended to involve the effects of the wall friction and powder particle diameter. From the present analysis it is well known that the flow characteristics inside and outside the thermal spray gun is varied depending on the combustion chamber pressure. The thermal spray gun flow is characterized by six different patterns. The powder particle size and wall friction significantly influence the powder particle velocity. The particle velocity decreases with an increase in the powder particle size. This implies that the combustion chamber pressure should be increased to achieve a higher velocity of the powder particle.

• 한국연소학회:학술대회논문집
• /
• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
• /
• pp.153-157
• /
• 2003

Supersonic and hypersonic aircrafts must pass wide range of speed to reach high speed region. But for existing engines the most efficient operating speed ranges are decided according to their flying speed, so an engine which mixes several engines like TRJ (Turbo Ramjet) and ARJ (Air Turbo Ramjet) has been planed. This mixed type engine has inefficiency that more than two engines must be installed simultaneously, but the pulse detonation engine (PDE) that uses detonation wave has a strong point that it can operate in all speed range with single engine. This paper deals with the simulation of the pulse detonation engine which uses hydrogen peroxide $(H_2O_2)$ mono propellant. Hydrogen peroxide is low-cost propellant, and it is reacted without oxidizer. Comparison between $H_2-O_2$ mixture with $H_2O_2$ mono propellant about thrust, pressure, temperature and velocity shows that $H_2O_2$ is a very useful propellant.

• 한국자동차공학회논문집
• /
• 제11권5호
• /
• pp.60-69
• /
• 2003

The simplified two-color method is proposed which can estimate the temperature distribution and the soot density of the whole flame with the image analysis of the high-speed photographs. The factors influenced on its processing were examined, for example, the selection of the wave length, the kind of films, the preparation of the calibration curve between the radiance of flame and the luminance temperature. The simplified two-color method reported in this paper can be used as a tool for the improvement of the combustion process in direct injection diesel engine.

• 한국추진공학회지
• /
• 제15권6호
• /
• pp.1-6
• /
• 2011

본 연구에서는 정상초음파장의 간섭에 의해 야기되는 예혼합화염의 구조 변이를 규명하기 위한 실험 결과를 제시한다. 화염전파를 관찰하기 위해 슐리렌 기법을 이용하였으며, 초기압력 및 연소챔버 개방 유무에 따른 화염선단의 형태 및 화염 전파속도를 고찰하였다. 정상초음파장에 의한 화염선단의 찌그러짐이 관찰되었고, 초음파장의 특성이 변하지 않는 한 그 수직방향으로의 위치는 일정하였다. 정상초음파의 영향을 받은 화염은 전파할수록 구조적 변화가 심해졌으며, 전파속도 또한 증가하였다. 반사파와 정상초음파의 영향으로 연꽃모양의 화염(lotus flame)이 형성되는 사실을 발견할 수 있었다.