• 대한기계학회논문집B
• /
• 제32권7호
• /
• pp.536-541
• /
• 2008

The Flow characteristics of a ship's propulsion mechanism of Weis-Fogh type, in which a airfoil(NACA0010) moves reciprocally in a channel, were investigated by the PIV. Velocity vectors and velocity profiles around the operating and stationary wings were observed at opening angles of ${\alpha}=15^{\circ}$ and $30^{\circ}$, velocity ratios of $V/U=0.5{\sim}1.5$ and Reynolds number of $Re=0.52{\times}104{\sim}1.0{\times}104$. As the results the fluid between wing and wall was inhaled in the opening stage and was jet in the closing stage. The wing in the translating stage accelerated the fluid in the channel. And the flow fields of this propulsion mechanism were unsteady and complex, but those were clarified by flow visualization using the PIV.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2005년도 추계학술대회 논문집
• /
• pp.69-73
• /
• 2005

Three-dimensional density distributions of an impinging and eccentric flame have been analyzed numerically and experimentally by a combined optical system with a digital speckle tomography. The flame has been ignited by premixed butane/air from air holes and impinged vertically against a plate located at the upper side of tile burner nozzle. In order to compare with experimental data, computer synthesized phantoms of impinging and eccentric flames have been made and reconstructed by a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique has been developed for the analysis of speckle displacements to investigate wall jet regions of the impinging flame including sharp variation of the flow direction and pressure gradient. The reconstructed temperatures have been compared with a temperature photography by an infrared camera and results of numerical analysis using a finite-element method.

• 대한기계학회논문집
• /
• 제17권12호
• /
• pp.3148-3165
• /
• 1993

A cascade wind tunnel test for a turbine nozzle, which was designed for a small turbo jet engine in a previous study, has been conducted to evaluate its aerodynamic performance and losses. The large-scale blades were based on the mid-span profile of the nozzle. Oil film flow structure, and then 3-dimensional velocity components were measured in the flow passage with a 5-hold pressure probe, in addition to turbulent intensities at mid-span of cascade exit using a hot-wire anemometer. From this study, 3-dimensional growth of horseshoe and passage vortices in the downstream direction was clearly understood with near-wall flow phenomena. In addition, secondary flow and losses associated with the blade configuration were obtained in detail.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권7호
• /
• pp.1036-1043
• /
• 2008

The Flow fields of a ship's propulsion mechanism of Weis-Fogh type were investigated by the PIV. Velocity vectors and velocity profiles around the operating and stationary wings were observed at opening angles of ${\alpha}=15^{\circ} and $30^{\circ}$, velocity ratios of V/U=$0.5{\sim}1.5$ and Reynolds number of Re=$0.52{\times}10^4{\sim}1.0{\times}10^4$. As the results the fluid between wing and wall was inhaled in the opening stage and was jet in the closing stage. The wing in the translating stage accelerated the fluid in the channel. And the flow fields of this propulsion mechanism were unsteady and complex, but those were clarified by flow visualization using the PIV.

• 대한기계학회논문집
• /
• 제7권2호
• /
• pp.218-225
• /
• 1983

측벽부착형 순유체조자에서 제어입력이 존재할 때 2차원 난류제트가 오프셋된 경사면에 재접합하 는 현상을 연구하였고 정상상태하의 재접합모델을 이론적으로 전개하였다. 순유체조자의 상하면 이 제트의 확산에 미치는 영향을 조사하기 위하여 제트의 중심선에 따라 최대속도를 측정하였고, 그 결과에 따라 본 모델에 사용한 제트확산계수(.sigma.)의 값은 자유제트의 것 (.sigma.=7.67)보 다 큰 .sigma.=10.5로 택하였다. 이론적 모델을 확증하기 위하여 제트의 재접합점과 변형각도에 관한 기존 논문에 보고된 실험적 연구결과와 비교하여 좋은 일치를 보았다.

• 한국연소학회지
• /
• 제7권3호
• /
• pp.32-36
• /
• 2002

A numerical study was carried out to investigate combustion phenomena in a model Scramjet engine, which had been experimentally studied at the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was Mach number 2.0 and the total temperature of hot flow was 1800K. Equivalence ratio was set to be 0.26 which is higher than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• 한국연소학회지
• /
• 제12권1호
• /
• pp.11-20
• /
• 2007

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Different shock tube fill pressures have various inflow conditions. $15^{\circ}$ inclined hydrogen fuel injection is located before the cavity. Oblique shock is generated from the cavity and reflects off the top and bottom wall. For non-reacting flow, fuel makes the shear layer thicker above the cavity therefore, the shock is generated just before the trailing edge. This research has self-ignition in the combustor. For reacting flow, as the equivalence ratio increases, flame starts to generate near the injector or occur in the recirculation zone before the injector. High fuel injection sustains the jet shape in the cross flow and air can mix with fuel along the shear layer. Therefore, two flame layers find above the cavity for high equivalence ratio.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
• /
• pp.127-132
• /
• 2001

A numerical study was carried out to investigate the combustion phenomena in a model Scramjet engine, which had been experimentally studied in the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was 2.0 in Mach number and the total temperature of hot flow was 1800K. Equivalence ratio was set to be rather higher value of 0.26 than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 제33회 추계학술대회논문집
• /
• pp.3-8
• /
• 2009

Wall flush mounted injector with various orifice shape and injection conditions, were examined to enhance jet penetration and mixing in supersonic cross flow, in view of application to air-breathing accelerator vehicle. Orifice shapes with high aspect ratio were found to preferable for better penetration in the cold flow, and in the reacting flow for scramjet-mode combustion conditions. However, the effectiveness of the high aspect ratio was diminished in the dual-mode combustion conditions. Supersonic injection was applied to the high aspect ratio orifice, and further increase in penetration was observed in the cold and reactive flow for scramjet-mode combustion conditions, however, mixing enhancement due to mixing layer / pseudo-shock wave system interaction was dominant in the dual-mode combustion conditions. Difficulty in attaining ignition in the case with the high aspect ratio orifice was encountered during the combustion tests.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1998년도 추계학술대회 논문집
• /
• pp.235-241
• /
• 1998

Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stroke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air maybe made to flow intermittently through a pipe. In this paper a exhaust system simulator of engine was used to experimentally analyzer the decrease inflow rate at high rotation speeds and to determine what variables, other than rotational speed, give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.