Atomization Improvement of a Liquid Jet with Wall Impingement and its Application to a Jet Engine Atomizer

Shiga, Seiichi The Institute for Liquid Atomization and Spray Sys 2006 한국액체미립화학회지 Vol.11 No.3

In the present study, capability of improving the liquid atomization of a high-speed liquid jet by using wall impingement is explored, and its application to a jet engine atomize. is demonstrated. Water is injected from a thin nozzle. The liquid jet impinges on a wall positioned close to the nozzle exit, forming a liquid film. The liquid film velocity and the SMD were measured with PDA and LDSA, respectively. It was shown that the SMD of the droplets was determined by the liquid film velocity and impingement angle, regardless of the injection pressure or impingement wall diameter. When the liquid film velocity was smaller than 300m/s, a smaller SMD was obtained, compared with a simple free jet. This wall impingement technique was applied to a conventional air-blasting nozzle for jet engines. A real-size air-blasting burner was installed in a test rig in which three thin holes were made to accommodate liquid injection toward the intermediate ring, as an impingement wall. The air velocity was varied from 41 to 92m/s, and the liquid injection pressure was varied from 0.5 to 7.5 MPa. Combining wall impinging pressure atomization with gas-blasting produces remarkable improvement in atomization, which is contributed by the droplets produced in the pressure atomization mode. Comparison with the previous formulation for conventional gas-blasting atomization is also made, and the effectiveness of utilizing pressure atomization with wall impingement is shown.

SUPPRESSED PROMPT ATOMIZATION OF FLASHBOILING SPRAY BY ELEVATING INJECTION PRESSURE

( Qinglin Xu ),( Min Xu ),( David L. S. Hung ),( Tianyun Li ),( Xue Dong ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

In a direct injection spark ignition (DISI) engine, the mixing time of the fuel with intake air in the cylinder is limited, thus quicker atomization and evaporation are desired. In general, there are two viable ways to promote these processes. One of them is by increasing the injection pressure, which has always been the key technology adopted by automobile manufacturers to improve the engine performance and meet the emission regulations. While high-pressure injection is already applied in most of the DISI engines, it has been reported that further increase of injection pressure is still beneficial on fuel efficiency and emissions reduction. In addition to this, flash-boiling is also regarded as an effective way to improve fuel atomization and evaporation with the potential to reduce fuel consumption and emissions. Existing research on flash-boiling spray mainly focuses on the multi-hole injector. Its plume-to-plume interaction phenomenon, as called “collapse”, has been thoroughly studied. Its benefits on atomization and evaporation have been proved. However, limited work has been done on the flash-boiling spray of a single-hole injector. Its breakup mechanism and movement behavior need to be further studied. Moreover, the study of high pressure gasoline spray beyond 35 MPa is also limited, especially at flash-boiling conditions. The effects of injection pressure on flash-boiling spray is still unrevealed. Therefore, the objective of this work is to study the influence of the superheat degree and injection pressure on the spray penetration and dispersion of a single-hole injector. Results show that in promoting dispersion and reducing penetration of the fuel, the effect of superheat degree was better than that of high injection pressure. In addition, increasing injection pressure of superheated fuel led to the increase in the tip penetration and decrease in the spray width while the injection pressure had opposite effects on subcooled fuel spray.

Atomization Using a Pressure-Gas-Atomizer

Achelis Lydia,Uhlenwinkel Volker,Lagutkin S.,Sheikhaliev Sh. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

An update and the latest results on molten metal atomization using a Pressure-Gas-Atomizer will be given. This atomizer combines a swirl-pressure atomizer, to generate a liquid hollow cone film and a gas atomizer to atomize the film and/or the fragments of the film. The paper is focused on powder production, but this atomization system is also applicable for deposition purposes. Different alloys (Sn, SnCu) were atomized to study the characteristics of the Pressure-Gas-Atomizer.

Effects of the Geometry of an Injector on the Atomization and Combustion Characteristics Using a Jet Engine Fuel Injector with Wall Impingement

( Satoshi Yamamura ),( Nobuaki Motegi ),( Mikiya Araki ),( Hideshi Yamada ),( Hisao Nakamura ),( Seiichi Shiga ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Effects of the geometry of a jet engine fuel injector with wall impingement on the atomization and combustion characteristics are investigated. The atomization characteristics were evaluated by mean droplet size (SMD) obtained by a light scattering technique (LDSA) under atmospheric condition. Combination of pressure atomization with air-blasting gives remarkable improvement of the atomization. The effect of droplet size and spray dispersion on the combustion characteristics are also investigated experimentally. Results showed that SMD decreased with the decrease in the nozzle diameter D. Spray dispersion became better with the decrease in the D. EI(NOx) decreased with the decrease in the D. Spray dispersion became worse with the decrease in N. EI(NOx) decreased with the increase in N. The relationship between the rate of decrease in SMD and the rate of decrease in EI(NOx) was defined and was verified to be useful. According to the result of the effect of nozzle number N on the atomization and combustion characteristics, it is shown that the dispersion is more important than the atomization.

On the empirical models for the discharge coefficient of pressure-swirl atomizers

( Moon Geun Hong ),( Jae Hyoung Jeon ),( Soo Yong Lee ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

For the design of injectors used for rocket engines, it is important to secure an appropriate discharge coefficient because the pressure loss of injectors is profoundly dependent on the pressure losses distribution in the whole propulsion system. Moreover the injector geometries are usually restricted by the available installation space in the manifold of a combustion chamber. An experimental study on the discharge coefficient of several tens of simplex pressure-swirl injectors with various dimensions has been performed. The experimental results show that the discharge coefficients of certain injector geometries especially with a low coefficient of nozzle opening seem not to be in accord with the previous empirical models. A novel empirical model is proposed for the prediction of the discharge coefficient of pressure-swirl atomizers with a low coefficient of nozzle opening.

기체주입식 분사기 내부 유동에서의 압력 섭동

홍문근(Moongeun Hong) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

기체주입식(Effervescent) 분사기는 액체 유동에 소량의 기체를 주입하여 분사기 내부에 형성된 기체/액체 이상유체 유동이 분사기 노즐을 빠져나오면서 고압의 기포들이 팽창/폭발하여 주위의 액체 유동을 미립화시킨다. 기체주입식 분사기는 소량의 기체유량과 작은 차압 조건에서도 우수한 미립화 특성을 보이지만, 근본적으로 분사기 내부의 이상유체 유동에 의한 미립화 불안성이 발생하게 된다. 본 논문에서는 미립화 불안성과 밀접히 연관되어 있는, 분사기 내부 이상유체 유동의 압력섭동 특성에 대한 실험결과를 간단히 소개하기로 한다. An effervescent atomizer employs the expansion and explosion of gas bubbles to disintegrate bulk liquid into small volumes. In spite of the advantages of this kind of atomizer, the quality of effervescent atomization is intrinsically affected by the characteristics of the internal two-phase flow, presenting the spray instability. With the aim of improving understanding of spray unsteadiness in effervescent atomization, the present study introduces some significant experimental results on the pressure fluctuation of the internal two-phase flow within an effervescent atomizer.

BREAKUP LENGTH OF CONICAL EMULSION SHEET DISCHARGED BY PRESSURE-SWIRL ATOMIZER

Rhim, Jung-Hyun,No, Soo-Young The Korean Society of Automotive Engineers 2001 International journal of automotive technology Vol.2 No.3

Many researches on pressure-swirl injectors due to the variety of application have been conducted on the effects of nozzle design, operating conditions, properties of liquid and ambient conditions on the flow and spray characteristics. The breakup length of conical emulsified fuel sheet resulting from pressure-swirl atomizer using in the oil burner was investigated with the digital image processing method with neat light oil and emulsion with water content of lotto% and the surfactant content of 1-3%. The injection pressure ranged from 0.1 to 1.2 MPa was selected. The various regimes for the stage of spray development within the experimental conditions selected in this study is newly suggested in terms of Ohnesorge number and injection pressure. The breakup length for both criteria show the same tendency even though the random nature of perforation and disintegration process of liquid sheet. The stage of spray development is widely different with the physical properties of liquid atomized, mainly viscosity of liquid. The breakup length decreases smoothly with increase in the injection pressure for the lower viscous liquid.

Atomization and Spray Formation of a Superheated Liquid Jet

( Won Ho Kim ),( Woong Sup Yoon ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Flash spray is distinguished from a cold spray in regard of abrupt changes in its thermal state through which the liquid-to-vapor phase change may assist the liquid breakup. In the present study spray formation and atomization of a superheated liquid jet due to a pressurized swirl nozzle were experimentally investigated. Injectant temperature is raised by a high frequency dielectric heating method and Global Sizing Velocimetry (GSV) measures the spray characteristics. Atomization quality is characterized in terms of dimensionless superheat degree, injection pressure and nozzle diameter. Smaller drops occur in the spray core region and local SMD distributions largely depend on the dimensionless superheat degree and the injection pressure. The region of the core drops is axially expanded with increasing in the injection pressure but it diminishes with increasing of the nozzle diameter.

Experimental Analysis of Breakup Length in Pressure-Swirl Atomiser

( Jung Ill Kim ),( Soo Young No ),( Young Jae Lee ) 한국액체미립화학회 2001 한국액체미립화학회 학술강연회 논문집 Vol.2001 No.-

Spray Characteristics of Electrostatic Pressure-Swirl Nozzle

( Gabriel Nii Laryea ),( Tae Gyoung Kang ),( Soo Young No ) 한국액체미립화학회 2001 한국액체미립화학회 학술강연회 논문집 Vol.2001 No.-