• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.395-398
• /
• 2010

감압비등에 의한 미립화는 더 미세한 직경의 액적을 얻을 수 있고, 분무각이 증가하며, 더 좋은 혼합특성을 갖는 다는 점에서 단순 압력식 미립화와 차이가 난다. 감압비등이란 과열된 액체를 포화 압력 이하의 대기 중으로 분사하여 급격한 비등에 의해 이루어지는 미립화이다. 본 연구는 금속 연료를 이용한 추진기관의 산화제인 물 공급기술에 감압비등과정을 이용한 와류분무를 적용시키기 위해 수행됐다. 분열길이와 같은 거시적 특성은 Charge-Couple Device(CCD) 카메라를 이용해 측정하였고, Sauter Mean Diameter(SMD)와 SMD분포와 같은 미시적 특성은 Global Sizing Velocimetry(GSV) 시스템을 이용해 측정했다. 실험은 압력과 온도, 대류 속도를 변화시키며 진행했다.

• Journal of Energy Engineering
• /
• v.7 no.1
• /
• pp.17-23
• /
• 1998

A simplified experiment was performed to figure out the atomization characteristics of highly viscous liquid of rice-bran oil by applying ultrasonic energy to improve the atomization of spray droplets. A spray system, an ultrasonic system, and three kinds of pintle-type nozzles(pin-edge angle: 5 , 10 , 15 ) were manufactured. To investigate the effects of ultrasonic energy on the atomization of a highly viscous liquid, a phase doppler particle analyzer was used for the measurement and calculation of spray droplets data. Nozzle opening pressures were chosen of 3 levels, i.e, 10, 13, 16 MPa. As a result, it could be concluded that the ultrasonic energy was effective to improve the spray atomization when applied to the fuel by means of 3 different nozzles because of the effects of the liquid fuel cavitation and relaxation between molecules caused by ultrasonic energy. The improvement rate of the spray atomization by the ultrasonic spray atomization by the ultrasonic spray compared with the conventional spray was about 10% increase in the case of pintle type nozzles. With the increase of pin-edge angles the distribution lines by nozzle opening pressures are declined for both conventional and ultrasonic sprays. This means that the increase of the pin-edge angle improves the atomization of sprays.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.3
• /
• pp.50-57
• /
• 2007

Spray characteristics of an injector in a small liquid rocket engine (LRE) is characterized by Particle Image Velocimetry (PIV) and Dual-mode Phase Doppler Anemometry (DPDA). Instantaneous plane images captured by PIV are examined for the qualitative prediction of spray breakup with the setup of evaluation technique for effect of spray angles on injector performance. DPDA is also applied in order to quantify the average velocity, turbulent intensity, SMD, and number density of spray droplets along the spray stream distance leading to precise observation of spray atomization behavior. An objective of the study is the derivation of design parameters of new injectors and the establishment of performance criteria through the clear understanding of spray characteristics.

• Journal of the korean Society of Automotive Engineers
• /
• v.15 no.5
• /
• pp.31-41
• /
• 1993

7. 음파의 흡수와 분산. 8. 초음파의 지향성. 9. 고유진동과 공명,공진. 9.1 고유진동. 9.2 공진,공명. 9.3 공진주파수. 10. 캐비테이션. 10.1 현상. 10.2 거동. 11. 초음파. 11.1 초음파의 발생기구.

• Journal of ILASS-Korea
• /
• v.20 no.2
• /
• pp.114-120
• /
• 2015

Effects of injection conditions on a pintle injector which is proper to recent liquid rocket engines requiring low cost, low weight, high efficiency and reusability were studied. The pintle injector with a typical moving pintle was used for atmospheric experiment using water and air. Injection pressures of water were considered 0.5 and 1.0 bar, 0.1 to 1.0 bar for injection pressures of air and 0.2 to 1.0 mm for pintle opening distance. Sauter mean diameters (SMD) of spray was measured at 50 mm distance from a pintle tip and SMD was treated as a representative parameter in this study. As a result, because of shape characteristics of the pintle injector, there was a transient region between the pintle opening distances of 0.6 and 0.7 mm and this region affected to mass flow rates and SMDs. Also, Reynolds numbers for gas, Weber numbers and momentum ratios were adopted as major non-dimensional paramters and the momentum ratio has strong correlation with SMD.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.159-162
• /
• 2007

The characteristic of air-assist spray injected into subsonic crossflow were studied experimentally. External-mixing air assist injector of Orifice nozzle with L/d of 3 were tested with various air-liquid ratio. Shadowgraph photography was performed for spray visualization and trajectory of spray measurements. The detailed spray structure was characterized in terms of SMD, velocity, and volume flux, using PDPA. Experimental results indicate that penetration length was increased and spray distribution was accelerated by increasing air-liquid ratio.

• Journal of ILASS-Korea
• /
• v.8 no.1
• /
• pp.37-40
• /
• 2003

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.9
• /
• pp.799-804
• /
• 2007

The behavior of spray emanating from an injector to be employed in a liquid-propellant thrust chamber is investigated by optical measurement techniques. The injector has eight holes, each of which has 30 cant angle from the center-axis with the diameter of 0.406 mm. In order to examine an atomization process according to the spray-generation conditions and the evolution along spray downstream, variational features in the velocity and size of droplets obtained through Dual-mode Phase Doppler An 799emometry (DPDA) are delineated and discussed together with instantaneous plane images captured by using Nd:Yag laser sheet beam. A categorization of spray-flow regime representing the atomization and turbulent nature is made through evaluating the non-dimensional parameters, i.e., Reynolds number and Weber number based upon the theoretical injection velocity. These qualitative and quantitative data of spray breakup will be a firm basis for the design of brand-new thruster

• Journal of Digital Convergence
• /
• v.10 no.5
• /
• pp.283-288
• /
• 2012

This study was undertaken to investigation the spray characteristics of the twin fluid atomization nozzle system. The light oil was injected at the normal temperature and injection pressure was 5 bar - 10 bar by 1 bar and volume flow was 0.5, 1.0 and 2,0 mmH2O(X10-2). We measured the SMD of sprayed droplet to study spray characteristics. The following conclusions were reached from the results of these study. 1. The more injection pressure increased, the more SMD decreased. 2. The more measuring distance between pressure nozzle tip and analyser beam increased, the more SMD increased. 3. SMD of the blower-air-added injection system were shown, increasing volume flow decreased respectively. The result of this study indicated the blower-air-added injection system induced beneficial changes in SMD. And it will be considered important indicator for spray characteristics design and performance evaluation of twin fluid atomization nozzle system.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.6
• /
• pp.104-109
• /
• 2004

On this paper study is concentrated on the breakup and atomization characteristics of spray formed by impinging jet injectors(like-doublet) used in liquid rocket engine(LRE). On the process of breakup and atomization, injection velocity and ambient gas pressure are the main parameters, so that these are used as variables that specify the experimental condition. Injection velocity varied from 3m/s to 30m/s and ambient gas pressure changed from 0.1MPa to 4.0MPa with nitrogen gas. As results, measured physical quantities decreased with increasing injection velocity and ambient gas pressure. But the decreasing ratios are different from those of the theory.