• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.258-263
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• 2008

Performance of injector equiped with screw type swirler which is suitable for supersonic cruise engine combustor was investigated using theoretical, numerical, and experimental methods. Based on discharge coefficient and spray angle which represent the performance of injectors, the geometrical parameters which affect these performance parameters were defined, control group injectors were designed, and variation of performance parameters according to the geometrical parameters were examined. Within the defined range, measured value of performance of injectors was smaller than result of theoretical prediction, and prediction result from numerical simulation using VOF method agreed with the result of experiments very well. The viscous barrier was not observed, and minimum discharge coefficient and maximum spray angle, 0.05 and 104 respectively, was obtained for this type of injector.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.88-96
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• 2017

As a part of the development procedures of scramjet engine with a regenerative cooling system, this experiment was performed using air-assist type injectors for scramjet engine. Two types of injectors were used in this experiment with the 90 and 60 degrees of the injection angle to the main flow. Mie-scattering was used for spray visualization and PDPA was used for the measurement of the atomization characteristics. It was found that increasing the pressure of supplied gas and the distance from nozzle tip led to the enhancement atomization characteristics and the injector with 60 degrees injection angle has better atomization characteristics than 90 degrees injector.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.52-59
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• 2007

Fuel injection system greatly affects the performance of a direct injection diesel engine. A common rail injection system was introduced to satisfy the stringent emission standards, low fuel consumption, and low noise in recent years. The performance of a common-rail fuel injection system is strongly influenced by the injector characteristics. The common rail injector has evolved in order to improve its injection performance. The piezo-actuated injector is more suitable for common rail injection system due to its fast response and is expected to replace current solenoid-operated injector. In this study, nonlinear mathematical models are proposed for the solenoid-operated and the piezo-actuated injectors for control applications. Based on these models, the injection rate, which is one of the most important factors for the injection characteristics, is estimated using sliding mode observer. The simulation results and the experimental data show that the proposed sliding mode observers can effectively estimate the injection timing and the injection rate for both common-rail injectors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.147-150
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• 2006

The influences of injection conditions and recess configuration of liquid-liquid swirl coaxial injector on spray characteristics were investigated. The characteristics of the coaxial spray in internal mixing injection region were mai y controlled by the merging phenomenon and momentum balance between two liquid sheets, but those in internal mixing injection region were influenced by the impingement phenomenon as well as momentum balance between two liquid sheets.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.877-880
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• 2011

A coaxial swirl/shear injector using GCH4/LOx as propellants was degisned and manufactured. Flow analysis by Fluent was performed to decide the number of orifice and the rear shapes of inlet orifice etc. Flow rate of the injector was measured according to differential pressure and uniformity of injector's spray pattern was confirmed by a patternator. The results showed that the difference of flow rate was around 10% and the spray angle of oxidizer was $66^{\circ}$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.658-661
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• 2011

A coaxial swirl/shear injector using GCH4/LOx as propellants was degisned and manufactured. Flow analysis by Fluent was performed to decide the number of orifice and the rear shapes of inlet orifice etc. Flow rate of the injector was measured according to differential pressure and uniformity of injector's spray pattern was confirmed by a patternator. The results showed that the difference of flow rate was around 10% and the spray angle of oxidizer was $66^{\circ}$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.146-149
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• 2006

Spray characteristics of an injector employed in mono-propellant hydrazine thrusters were investigated by PIV(particle image velocimetry) and LDA/PDA(laser/phase Doppler anemometry) techniques. The instanteneous plane image data captured by PIV measurement were examined in order to judge a pass-fail criteria of spray injection performance according to the specific pressure supplied. LDA/PDA technique were also applied to measure the velocity and droplet size of spray were not obtained from PIV measurement. The objective of this experimental study was the clear understanding of spray characteristics as well as the derivation of injector performance to understand clearly the spray characteristics by comparing the both results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.289-292
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• 2009

Injector dynamics of multi swirl injectors in an annular combustor have been investigated by LES(Large Eddy Simulation) turbulent model with MPI parallel computation technique. The present study employs the LM6000 lean premixed swirl-stabilized annular combustor. Real shape combustor is simulated in order to investigate the detail interaction mechanism among multi-injectors. The strong vortex breakdown occurs at the impinging surface between the adjacent injectors so that the complex and strong oscillatory pressure propagates inside of the combustor. Tangential pressure fluctuation mode was captured by including multi injectors in computational domain.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.141-144
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• 2009

An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE). This paper is focused on the injection performance of a small LRE-injector by employing the spray characteristic parameters made up of the velocity, Sauter mean diameter, and turbulence intensity. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along transverse axis, spatially. The Weber number and Reynolds number are used to characterize the atomization and turbulence nature of injector spray.

• Journal of ILASS-Korea
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• v.19 no.1
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• pp.9-14
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• 2014

Performance of DI diesel engine with high-pressure fuel injection equipment is directly related to its emission characteristics and fuel consumption. So, the electro-hydraulic injector for the common-rail injection system should be designed to meet the precise high fuel delivery control capability. Currently, most high pressure injector in use has a needle driven by the solenoid coil energy or the piezo actuator controlled by charge-discharge of output pulse current. In this study, macroscopic spray approaching method was applied under constant volume chamber to research the performance of three different injectors : solenoid, indirect-acting piezo and direct-acting piezo type for CR direct-injection. LED back illumination for Mie scattering was applied on the liquid spray visible of direct-acting piezo injector, including hydraulic-servo type solenoid and piezo-driven injectors. As main results, we found that a direct-acting piezo injector had better a spray tip penetration than hydraulic-servo injectors in spray visualization.