• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.2100-2108
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• 2001

The impinging tones by high-speed plane jets are experimentally investigated to study the edgetone characteristics. Experiment used a slit nozzle and a wedge system to generate edgetones. The jet in the experiment is varied from low to high subsonic speed to obtain the effect of the speed on the frequency characteristics of impinging tones. The experimental data obtained previously fur edgetones and platetones by various nozzles are compared with the present edgetone data. And the condition of tone generation, the frequency ranges, the effective source point and the sound pressure level are compared and discussed. It is found that the jet speed has no diect influence on the impinging tone characteristics. Regardless of the jet speed, the effective source point is about a quarter wavelength downstream from the edge tip. With increase in jet speed, the influence of the nozzle configuration is decreased and the operating frequencies show good coincidences by normalized parameters based on the slit thickness.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.5
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• pp.442-449
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• 1984

Turbulent jet flow has been studied in many ways; a plane jet, a rectangular jet, an annular jet, a round jet, a wall jet, a parallel jet, a valve jet, a cross jet, a slit jet and etc. In this report, a 45.deg. cross jet flow was tried by using two same dimensioned nozzels(dia..phi.20)which were set up at the exit of the subsonic wind tunnel. Each jet flows to the direction of 22.5.deg. to the axis of downstream of the mixed flow. The centerline of each jet meets at the distance of 217.3mm and their mixing flow could be imagined to develop beyond that distance, so the measurement was effectuated at X/X$_{0}$=1.2-1.5. The section of the mixed flow a elliptic circle which is formed by the 22.5.deg. inclined flows to the X direction. This experimental study aimed at the investigation of the turbulent mixing process of two jets; the mean velocities, the turbulent shear stresses, the correlation coefficients, and the momentum were respectively measured. The mean velocity distribution profiles of the down-stream component measured in the Y direction coincide well with the empirical equation of Gortler and those measured in the Z direction agree with the equation of H. Schlichting. Other mean velocities V over bar and W over bar components were randomly distributed. The higher values with same order of the intensity of turbulence were largely distributed at the central part of the flow. The momentum was decreased up to 70% by the shock losses and the development of intense turbulences, but it kept its value constantly beyond X/d=14. Two-channel hot-wire anemometer systems (model 1050 series), X-type hot-wire made of tungsten (dia. .phi.e.mu.m, long 3mm, model 0252 T5), a computer(model HP 9845B0, and a plotter (model HP 9872C) were used for the experiments and the analyses.s.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.115-122
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• 2007

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.486-491
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• 2008

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.257-265
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• 1981

A modified subsonic wind tunnel was employed to investigate the turbulent flow of a valve jet. To effectuate this experimental study, an actual valve and valve seat of a diesel engine were equipped at its outlet (ref. Fig. 3) Theoretically, using the equation of motion of Navier-Stokes in the chlindrical coordinates, the turbulent equation of motion for the incompressible fluid was derived with three assumptions; steady flow (.delta./.delta.t=0), axisymmetry and revolutionary homogeneity(.delta./.delta..phi.=0), no ensemble revolution (V.iden.0). Experimentally, mean and fluctuation velocities have been measured in the redial direction. With a assumption of a non-dimensional velocity distribution equation, a sami-emperical similarity profile equation of the jet flow have been derived, whose empirical constants were deterimed graphically with the data obtained.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.1
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• pp.107-115
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• 2002

In this paper, spray and combustion characteristics of a liquid-fueled ramjet engine were experimentally investigated. The spray penetrations were measured to clarify the spray characteristics of a liquid jet injected transversely into the subsonic vitiated airstream, which Is maintained a high velocity and temperature. The spray penetrations are increased with decreasing airstream velocity, increasing airstream temperature, and increasing air-fuel momentum ratio. To compensate our results of penetrations, the new experimental equation were modified from Inamura's equation. In the case of insufficient penetration, the combustion phenomenon in ram-combustor were unstable. Therefore, the sufficient penetration must be considered to make a stable flame.

• Journal of computational fluids engineering
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• v.6 no.2
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• pp.1-8
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• 2001

Despite the massive effort which has been given to the analysis of the base flows, one commonly occurring case seems to be overlooked. This is for base (rearward facing surface) which is between a subsonic flow and supersonic flow. Potential flows of the air and gas streams are computed for the flow past a separated wake. Then a viscous jet mixing is superimposed on this inviscid solution. Conservation of mass, momentum and energy is achieved by multiple iterations. Despite the iterations, the wake flow field is computed with modest computer requirements.

• Proceeding of EDISON Challenge
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• 2016.11a
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• pp.74-77
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• 2016

본 연구에서는 Scream Jet Intake에 발생하는 충격파 경계층에서 속도를 Supersonic에서 Subsonic으로 줄였을 때의 상호작용을 EDISON_CFD로 해석하기로 한다. 이상적인 공기 유동에서 충격파 경계층의 각도를 $15^{\circ}{\sim}20^{\circ}$, $25^{\circ}{\sim}30^{\circ}$, $15^{\circ}{\sim}40^{\circ}$, $25^{\circ}{\sim}50^{\circ}$와 같이 두 개($5^{\circ}$, $25^{\circ}$)의 각도 차이를 두어 이중압축램프에서의 유동현상을 EDISON_CFD로 수행하고 분석하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.1-8
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• 2005

This paper explored the effects of separation control through the use of pulsating jet blowing on a two dimensional elliptical airfoil. To develop an active control technique of flow separation, a flow control actuator utilizing continuous/pulsed jet of pressurized air was designed and installed in a wind tunnel testing model of elliptic wing. PIV measurement and flow visualization of the wing near field were conducted to access the feasibility and effectiveness of the pulsed jet blowing on controlling the stall of the elliptical wing in subsonic flow. PIV experimental results show that separation control can provide significant reduction in turbulent flow wake and separation bubbles by jet blowing. The pulsating jet blowing is more effective on the separation control than continuous one. Increased jet frequency suppressed the turbulent separated flow wake effectively at even higher AOAs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.155-158
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• 2005

The spray characteristics of liquid jet minted in subsonic cross-flow were investigated numerically and experimentally. The behaviors of column, penetration and breakup of plain liquid jet in non-swirling cross-flow of air have been studied. Numerical and physical models are based on a modified KIVAII code. The primary atomization is represented by a wave model based on the KH(Kelvin-Helmholtz) instability that is generated by a high interface relative velocity between the liquid and gas flows. CCD camera has been utilized in oder to capture the spray trajectory. The nozzle diameter was 0.5 mm and its L/D ratios were between 1 and 5. Numerical and experimental results indicate that the breakup point is delayed by increasing gas momentum ratio, the penetration decreases by increasing Weber number and the turbulent or nonturbulent liquid jet is obtained at different L/D ratio.