• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.44-50
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• 1999

For the prediction of combustion performance of the Unlike Impinging Quadlet Injector (OOOF type), mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity were obtained from the cold test. Water/kerosene were used for simulants, The momentum ratio of oxidizer and fuel were mixing correlating parameter. Orifice discharge coefficient, spray pattern and mass distribution were measured. As a result, invasion-depth had strong effect on mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity. Mixing efficiency and efficiency of mixing characteristic velocity showed maximum value for momentum ratio 1.67(TMR = 2.5), and fuel rich state showed larger decreasing ratio than oxidizer rich state.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.17-24
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• 2010

This study was performed to make a close inquiry into a pseudo 3-dimensional structure of the liquid-propellant spray emerging from nonimpinging-type injector. Spray configuration near the injector exit was captured by a high-speed camera, and then its periodic phenomena (shedding) was observed. Detailed spatial structure of spray was investigated by spray characteristic parameters (velocity, diameter, volume flux, etc.) with the aid of a Dual-mode Phase Doppler Anemometry (DPDA). Experiment was carried out at various locations along the geometric axis of the nozzle orifice and on the plane normal to the spray stream with the injection pressures of 17.2 to 27.6 bar.

• International Journal of Automotive Technology
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• v.5 no.1
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• pp.9-16
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• 2004

An experimental study was carried out to characterize the spray atomization process of micro-machined port fuel injectors with a piezoelectric atomization device, which can generate pressure pulsations through vibration of a piezoelectric transducer. In this study, several types of micro-machined arrays such as 30∼200-microns of hole arrays were tested. Both a dual-stream and a central-port injectors with micro-machined arrays were tested and compared with normal port fuel injectors. The spray visualization was conducted to characterize overall spray structure and phase Doppler particle analyzer (PDPA) system was used to quantify the droplet size and velocity. In addition, the pressure history was recorded by using digitized signal from pressure transducer. The results showed that modulation is effective to the spray atomization for tested injectors and atomization performance depends on injector design factors, orifice sizes, and frequency and power of the modulator. A number of resonance frequencies of the modulator was modified by injector parameters and temperature. In addition, our results suggested that design of sufficient space among holes is critical to avoid droplet coalescence in the multi-hole micro-machined injectors.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.3
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• pp.30-37
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• 2003

Spray angle of dual swirl injector is established according to the velocity ratio at orifice exit. Due to the internal mixing at recess and lack of correlation for the combined two fluid injection, prediction of spray angle is very difficult. This study deal with experimental work and numerical simulation on spray angle with different recess length. Among the multiphase flow models, the VOF model was selected to simulate the spray angle. Feasibility of numerical analysis are confirmed by comparing the results with the experimental data, and the effect of recess on spray angle are analyzed for single and combined spray case.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.5-8
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• 2010

The GCSC injectors studied in this paper are those applied to the combustion chamber of staged combustion engines. Liquid fuel is injected through tangential holes along the outer wall of the GCSC injector forming a swirling sheet and oxygen rich gas generated by a preburner enters axially through the center orifice of the injector to form a gaseous jet. The spray characteristics of GCSC injectors under ambient/high pressure conditions and the effect of recess on spray characteristics have been examined in this paper. These results are expected to be used as fundamental data to develop of a staged combustion engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.180-186
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• 2012

A water-flow test for acceptance verification is carried out for a nonimpinging-type injector prior to the design-performance verification of 70 N-class liquid-rocket engine under development. It is observed that there exist varying characteristics of atomization among the injector-orifices caused by a fabrication crudeness of orifice holes which can be judged from a microscopic standpoint. The flow shedding phenomenon and ruffle on the surface of liquid column (or droplet) could be caught from the instantaneous spray images.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.2
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• pp.119-126
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• 2014

An experimental study was conducted to study fuel injection characteristics through plain orifice injectors when the fuel was heated to the temperature higher than its boiling point. Three injectors with different orifice diameters were used to measure the flow coefficient (${\alpha}$) for the injection pressure ranges of 3, 5, and 10 bar and the fuel temperature ranges between 50 and $270^{\circ}C$. The study showed that ${\alpha}$ decreases gradually with the fuel temperature below $180^{\circ}C$ while it drops abruptly when the temperature goes beyond $187^{\circ}C$, the boiling temperature of the fuel. The slope of ${\alpha}$ bifurcated at the boiling temperature for different injection pressures, and ${\alpha}$ decreased faster for the lower injection pressure due to the more active boiling in the injector. In addition, the larger orifice diameter had the higher ${\alpha}$ value, and ${\alpha}$ jumped at moderate temperature ranges when the injection pressure was low, implying the turbulent-laminar transition phenomena. The measured ${\alpha}$ was plotted against the cavitation number($K_c$), and the characteristics were independent of the applied pressure for small injectors when the fuel was evaporated before it was injected.

• Journal of ILASS-Korea
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• v.20 no.2
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• pp.82-87
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• 2015

A nozzle with vortex generator was used to develop the low pressure nozzle with high atomization performance and the nozzle atomized the liquid by centrifugal shear forces. In order to analyze the atomization characteristics, a shadowgraphy method was used and the measurement of droplet size was performed by using laser diffraction analyzer. The liquid injection pressure was fixed as 0.03 bar which is very low pressure and the gas injection pressures were changed from 0 bar to 2.0 bar. As a result, the breakup was achieved at the air injection pressure of 0.25 bar and over. The nozzle with the orifice diameter of 0.4 mm and the orifice gap of 0.25 mm presented small droplet diameters under 50 at the air injection pressure of 0.75 bar.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.119-126
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• 2001

The effects of injection pressure and the distance between injectors on the droplet distribution characteristics of liquid spray for dual orifice type swirl injectors were experimentally investigated. The SMD distributions, volume concentration and Rosin- Rammler variation N of liquid spray droplets for water and a fuel were measured by using the laser diffraction particle sizer. The results of present study show that SMD decreases and spray angle increases as the injection pressure increases. The interaction of sprays from two injectors gives more uniform SMD distribution in the radial direction. As the distance between two injectors increases, SMD that is measured in the interacting region increases. The effect of viscosity on the droplet distribution in the interacting region is greater than the that of surface tension of liquid.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.173-178
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• 2003

An experimental study is conducted to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice type swirl injector which is used in gas turbines. The major parameters affecting spray characteristics are fuel temperature and injection pressure entering into the injector. Fuel temperature is shown to have strong influence on the spray characteristics especially at a lower temperature. In this study, fuel temperature is varied from $30^{\circ}C$ to $120^{\circ}C$ and injection pressure is altered from 3 to $7 kg_{f}$ /$cm^{2}$. Two kinds of fuel, which have different surface tension and viscosity, are chosen as an atomizing fluid. As a result, injection instability occurs in the low temperature range due to icing phenomenon and the change of fuel properties. As the injection pressure increases, the kinematic viscosity range for stable atomization becomes wider. The factor controlling the SMD of spray is substantially different depending on the fuel temperature range.