Effect of Tapered Nozzle Hole on Spray Characteristics of High Pressure Diesel Injection

( Jang Sik Kong ),( Choong Sik Bae ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

Tapered nozzle hole increases the discharge coefficient and reduces the cavitation in the hole. Non-evaporating diesel sprays from common-rail systems were characterized to investigate the effect of tapered nozzle-hole in diesel injector. Macroscopic spray parameters including penetration and spray angle were analyzed from spray images at constant volume chamber using high speed camera and spark light. Microscopic images of initial spray and spray angle oscillation at near nozzle hole exit were obtained with a long distance microscopic lens. Injection rate shape was measured using the injection rate meter with Bosch tube method. The velocity and particle size of droplets were measured using a phase Doppler anemometer system. It was found from the result of injection rate shape that initial increasing slope of injection velocity from tapered nozzle hole was higher than that of straight nozzle under the same injection pressure. The peak flow velocity from tapered nozzle hole was also higher. At initial stage, spray penetration increased according to injection rate change. As enough time elapsed from start of injection, spray penetration increased according to the square root of time. Spray tip penetration in-creased with tapered nozzle hole because of higher initial injection velocity. And at the vicinity of nozzle hole exit, spray angle decreased with tapered nozzle hole because of strong spray axial momentum. Sauter mean diameter (SMD) at the downstream value with tapered nozzle hole was smaller than that of straight nozzle hole due to higher initial injection and increased air/fuel momentum exchange.

다단형 실린더를 가지는 가변형 임계노즐 유동에 관한 연구

이준희(Jun-Hee Lee),김희동(Heuy-Dong Kim),박경암(Kyung-Am Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Critical nozzle is a reliable flowmeter by using flow properties at the nozzle upstream and the nozzle throat diameter. Therefore, for the critical nozzle is to be utilized at a wide range of operating conditions, the nozzle throat diameter should be changed depending upon the nozzle supply conditions. The present study describes a new method to enlarge the range of mass flow rate measurement of the critical nozzle by using a multiple-stage cylinder which changes the critical nozzle throat diameter. Each stage of the multiple-stage cylinder makes the accurate control of the nozzle throat diameter possible and is connected to the slope to facilitate the flow. A computational work using 2-dimensional, axisymmetric, compressible, Navier-Stokes equations is carried out to simulate the gas flow inside the critical nozzle. The critical nozzle throat diameter is changed using the multiple-stage cylinder under a wide range of operating pressures. It has been found that the discharge coefficient is very sensitive to the variation of cylinder diameter, leading to the much reduced discharge coefficient as the cylinder diameter increases.

가변식 송풍노즐을 이용한 건설폐기물 중 이물질 제거 효율에 관한 연구

권영호 ( Young-ho Kwon ),송기순 ( Ki-soon Song ) 한국환경기술학회 2005 한국환경기술학회지 Vol.6 No.1

개발된 가변식 송풍nozzle을 이용한 건설폐기물 중 이물질 제거 효율에 대하여 실험한 결과 다음과 같은 결론을 얻었다. 개발 제품에서 가변식 송풍nozzle각도 75°의 경우는 평균효율이 99.53%로 나타났으며, 60°의 경우 평균효율은 86.37%로 나타났다. 가변식 송풍nozzle각도 45°의 경우는 평균효율이 82.32%로 나타났다. 또한, 고정식 송풍방식의 평균 제거효율은 69.43%, 개발된 가변식 송풍nozzle을 사용한 장치는 평균 99.53%로 약 30%정도가 높게 나타났으며, 투입되는 폐콘크리트속에 함유된 이물질량의 증가에도 제거효율은 최대 3.8%의 차이를 나타내어 본 실험에서 사용된 제거장치는 신뢰성있는 제거효율을 나타냈다. 실험 결과로 이물질의 성상에 따라 제거효율이 다르지만, 개발된 가변식 송풍nozzle의 각도가 클수록 이물질 제거효율이 높은 것으로 나타났으며, 고정식 송풍장치의 제거효율보다 개발된 가변식 송풍nozzle을 사용한 장치가 제거효율이 월등히 우수한 것으로 나타났다. 이것은 개발된 가변식 송풍nozzle을 자유 자제로 제어할수 있어 재생골재 생산시스템에서 이물질 제거효율에 영향을 크게 미치는 것으로 분석되었다. This study experimented about alien substance removal rate among construction waste that use developed variableness way ventilation nozzle. In development product variableness way ventilation nozzle occasion of 75˚ average rate by 99.53% appear, and in the case of 60˚, average rate appeared by 86.37%. Variableness way ventilation nozzle occasion of 45˚ average rate by 82.32% appear. Also, removal rate of fixed type ventilation system 69.43%, the system which use the Variableness way ventilation nozzle which is developed appears highly about 30% by 99.53%, Exclusion device used in this experiment displayed removal rate that have trustability that display difference of maximum 3.8% is authoritativeness in augmentation of an alien substance quantity that is included in engaged waste concrete. Removal rate differs according to property and state of alien substance by experiment sequence, but was expose that alien substance removal rate is high as angle of developed variableness way ventilation nozzle is big, and device that use variableness way ventilation nozzle developed than removal rate of fixed type ventilation system appeared by thing which removal rate is Excellently melancholy. This was construed that developed variableness way ventilation nozzle affects greatly in alien substance removal rate in recycled aggregate productive system.

Experimental Investigation of Nozzle Cavitating Flow Characteristics for Diesel and Biodiesel Fuels

서현규,박수한,이창식 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.2

This study was performed to clarify criteria for cavitation inception and the relationship between flow conditions and cavitation flow patterns of diesel and biodiesel fuels. The goal was to analyze the effects of injection conditions and fuel properties on cavitating flow and disintegration phenomena of flow after fuel injection. To accomplish this goal, it was utilized a test nozzle with a cylindrical cross-sectional orifice and a flow visualization system composed of a fuel supply system and an image acquisition system. In order to analyze the rate of flow and injection pressure of the fuel, a flow rate meter and pressure gauge were installed at the entrance of the nozzle. A long distance microscope device equipped with a digital camera and a high resolution ICCD camera were used to acquire flow images of diesel and biodiesel, respectively. The effects of nozzle geometry on the cavitating flow were also investigated. Lastly, a detailed comparison of the nozzle cavitation characteristics of both fuel types was conducted under a variety of fuel injection parameters. The results of this analysis revealed that nozzle cavitation flow could be divided into four regimes: turbulent flow, beginning of cavitation, growth of cavitation, and hydraulic flip. The velocity coefficient of diesel fuel was greatly altered following an increase in flow rate, although for biodiesel, the variation of the velocity coefficient relative to the rate of flow was mostly constant. The cavitation number decreased gradually with an increase in the Reynolds number and Weber number, and the discharge coefficient was nearly equal to one, regardless of cavitation number. Lastly, it could not observe cavitation growth in the tapered nozzle despite an increase in fuel injection pressure. This study was performed to clarify criteria for cavitation inception and the relationship between flow conditions and cavitation flow patterns of diesel and biodiesel fuels. The goal was to analyze the effects of injection conditions and fuel properties on cavitating flow and disintegration phenomena of flow after fuel injection. To accomplish this goal, it was utilized a test nozzle with a cylindrical cross-sectional orifice and a flow visualization system composed of a fuel supply system and an image acquisition system. In order to analyze the rate of flow and injection pressure of the fuel, a flow rate meter and pressure gauge were installed at the entrance of the nozzle. A long distance microscope device equipped with a digital camera and a high resolution ICCD camera were used to acquire flow images of diesel and biodiesel, respectively. The effects of nozzle geometry on the cavitating flow were also investigated. Lastly, a detailed comparison of the nozzle cavitation characteristics of both fuel types was conducted under a variety of fuel injection parameters. The results of this analysis revealed that nozzle cavitation flow could be divided into four regimes: turbulent flow, beginning of cavitation, growth of cavitation, and hydraulic flip. The velocity coefficient of diesel fuel was greatly altered following an increase in flow rate, although for biodiesel, the variation of the velocity coefficient relative to the rate of flow was mostly constant. The cavitation number decreased gradually with an increase in the Reynolds number and Weber number, and the discharge coefficient was nearly equal to one, regardless of cavitation number. Lastly, it could not observe cavitation growth in the tapered nozzle despite an increase in fuel injection pressure.

Experimental prediction of multi-nozzle spray characteristics for optimal design in a lead frame etching process

최민성,음성용,성연모,노기율,최경민 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

The objective of this paper is to provide quantitative information of uniform impact forces on the sprayed surface in order to optimize the multi-nozzle spray etching system. Spray characteristics obtained from optical non-intrusive measurements using particle image velocimetry (PIV) and particle motion analysis system (PMAS) are measured in single- and twin-nozzle sprays, and then the multi-nozzle spray characteristics is simulated based on those of measurement data. The influences of the multi-nozzle arrangement, nozzle pitch, and pipe pitch on the spray characteristics such as droplets’ velocity, diameter, number density, impact force and their uniformity are properly evaluated. The experimental cases E1 and E2 represent single-spray nozzle A and B, respectively. For twin-spray tests, three nozzle combinations, namely E3 (nozzle A-A), E4 (nozzle A-B) and E5 (nozzle B-B) are considered with different nozzle pitches. The multi-spray simulation cases S1 and S6 represent the multi-spray cases with a homo-nozzle arrays which is consisted in all nozzles of nozzle A or B. For cases from case S2 to S5, the multi-spray cases with a hybrid-nozzle arrays which is consisted in all nozzles of nozzle A and B. The results show that the impact force increases approximately twice as much for changing of experimental test cases from E1 to E5 owing to the differences in nozzle characteristics of single-sprays and the overlap region between two adjacent nozzles. For the multi-nozzle spray simulation, the uniformity of impact force (UI) is increased with increasing the number of nozzle B which has larger orifice diameter and a wider spray angle. The optimum multi-nozzle spray arrangement is case S4 with more than 90 % UI, based on the fact that the UI is quite stable with increasing the nozzle pitch ranging from 90 mm to 145 mm.

Cross-talk effect in electrostatic based capillary array nozzles

최경현,Khalid Rahman,Arshad Khan,김동수 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.12

Electrohydrodynamic printing is a promising technique for printed electronics application. Most researchers working in this field are using a single nozzle configuration. However, for large area printing a multi-nozzle setup will be required for time and cost effective process. In this paper the influence of electric field and flow-rate on jetting angle on multi-nozzle array has been investigated experimentally. A three nozzle setup has been used in a linear array by using glass capillary as a nozzle with independent voltage applied on each nozzle and independent ink supply. The experiments are performed by changing the nozzle to nozzle gap and the effect on the jetting angle has been investigated. It has been observed that by increasing the applied voltage the jetting angle also increases at fixed flow-rate. In case of increasing the flow-rate, the jetting angle first increases with increase in flow-rate, but as the flow-rate increases at certain level the jetting angle decreases; moreover, at a high flow-rate the cone-jet length starts increasing. Numerical simulation has been performed to have a better understanding of the electric-field with respect to jetting angles. The influence of one nozzle on another nozzle is also investigated by operating the nozzle independently by using different operating cases. The cross-talk effect is also minimized by reducing the nozzle diameter. At 250 μm nozzle diameter the cross-talk effect was negligible for 5 mm nozzle-to-nozzle gap. This study will help in better understanding of the interaction between different nozzles in multi-nozzle cases and better design of the multi-nozzle system by minimizing the effects of adjacent nozzles for multi-nozzle electrohydrodynamic printing system.

선형 오일러 방정식을 이용한 노즐의 연소불안정 감쇠 효과 평가

김준성,문희장 한국추진공학회 2019 한국추진공학회지 Vol.23 No.6

The wave motion inside the nozzle is known as one of the major damping elements of the rocket’s combustion instability by it’s aeroacoustic effects that result from the flow passage through the nozzle throat. These effects can be quantitatively evaluated by the nozzle admittance. In this study, one-dimensional linearized Euler equation was adopted to calculate the nozzle admittance, and trend analysis was performed depending on the nozzle’s main design variables. As a result, when nozzle converging part shortens, it is verified that the frequency dependency of the nozzle admittance is decreased due to the widened frequency range with lowered longitudinal nozzle admittance. Also, admittance estimation using the short nozzle theory is not appropriate when the first tangential mode of the pressure perturbation arises. 노즐 내 파동은 노즐목을 빠져나가는 유동의 공력음향학적인 효과로 인해 연소불안정을 감쇠시키는 주요 요소 중 하나로 알려져 있다. 이와 같은 효과는 노즐 어드미턴스라는 지표를 통해 정량적으로 평가가 가능하다. 본 연구에서는 현재까지 로켓 연소불안정 억제에 가장 효과적인 노즐감쇠(nozzle damping)와 연계된 노즐 어드미턴스를 구하는 여러 기법을 소개한다. 이중, 가장 널리 알려진 1차원 선형 오일러 방정식을 도입하여 노즐의 주 설계 변수에 따른 노즐 어드미턴스의 경향을 분석하였다. 분석 결과, 노즐 수축부 길이가 짧아질수록 축방향 노즐 어드미턴스의 값이 낮게 나타나는주파수 영역대가 확장되므로 짧은 노즐일수록 주파수 의존성을 줄인다는 기존 이론을 검증하였다. 또한, 짧은 노즐 이론을 통한 어드미턴스 예측은 1차 접선방향 압력 섭동에는 적합하지 않음을 알수 있었다.

관창의 유동특성에 관한 연구

이동명 한국화재소방학회 2003 한국화재소방학회논문지 Vol.17 No.3

본 연구에서는 관창의 유동특성예측을 위한 해석이론을 정립하고 수치해석으로부터 방수량과 방수형태를 예측하였다. 예측 데이터로부터 관창의 방수형태가 노즐과 니들의 위치에 따라 결정됨을 알 수 있었고, 관창의 유동특성은 노즐과 니들의 형상에 따라 그 특성이 결정됨을 알 수 있었다. 관창의 유동특성과 예측 데이터로부터 화재진압의 효율성을 극대화할 수 있는 새로운 관창의 모델이 제시되었다. 본 연구의 결과가 새로운 모델의 관창을 개발하는데 필요한 자료로 활용할 수 있을 것으로 보며, 또한 관창의 원천기술 확보, 동종업계의 기술력 파급효과 증대 및 소방분야의 기술개발 활성화 등에 이바지하고 자 한다. This study established analysis theory for flow characteristics prediction of the spray nozzle and predicted discharge and discharge type of the spray nozzle from numerical analysis. It could know that discharge type of the spray nozzle from prediction data determine to position of nozzle and needle, and flow characteristics prediction of the spray nozzle could know that the characteristics according to shape of nozzle and needle is decided. New model of the spray nozzle that can maximize efficiency of fire suppression from flow characteristics and prediction data of the spray nozzle is presented. The result of this study utilize to data necessary to develop new model of the spray nozzle. Also the result of this study wish to contribute to resource technology security of the spray nozzle, technique ripple effect enlargement of same kind industry and technical development activation of fire protection field etc.

미립화 및 분무장치 1 : 타원형 노즐의 내부유동 구조가 액주분열에 미치는 영향

홍정구 ( Jung Goo Hong ),구건우 ( Kun Woo Ku ),이충원 ( Choong Won Lee ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

An experimental study was conducted to investigate the atomization characteristics of a circular nozzle and elliptical nozzles of small diameter (0.5mm) under the high injection pressure (1MPa~9MPa). Furthermore, num erical simulations were attempted to investigate the internal flow structure in the circular and elliptical nozzles. This study showed that the disintegration characteristics of the liquid jet of elliptical nozzles were much differ ent from those of the circular nozzle. In the case of the circular nozzle, the surface of liquid jet was much smooth near the nozzle exit under the injection pressures of this study. But, in the case of the elliptical nozzles, surface waves on liquid jet have been generated and grown with increase of the injection pressure. As a result, surface breakup was observed with the increase of injection pressure because a rough column surface caused by growth of surface wave is disintegrated to ligament as the relative velocity between the liquid jet and ambient air increases. Furthermore, the numerical simulations informed that the internal flow structure of elliptical nozzle was quite different from that of the circular nozzle. The internal flow structure of the elliptical nozzle in hydraulic flip was reattached to the orifice wall of the minor axis unlike the flow in the circular nozzle which is detached from orifice wall. It has been concluded that the internal flow structure of the elliptical nozzle has influence on the disintegration characteristics of the liquid jet issued from the elliptical nozzle.

Effect of Internal Structure of Pressure-Swirl Nozzle on Atomization Characteristics

( Rakhul Chandrahasan ),( Seungwha Ryu ),( Young Choi ),( Chulju Ahn ),( Jeekeun Lee ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-

The spray characteristics of four different pressure-swirl type duplex nozzles were experimentally investigated. Duplex type nozzle consists of two nozzles, named as pilot and main nozzle where pilot nozzle is fixed inside the main one. Spray characteristics are experimentally analyzed by using Phase Doppler Anemometer (PDA) and Particle Image Velocimetry (PIV) at different operating conditions. PDA is used for droplet size and velocity measurement and PIV is used for spray visualization with Jet A-1 fuel as testing fuel. Two of the nozzles are used to investigate the effect of shape of pilot nozzle tip, one is flat and another one is cone shape and other the other two nozzles are used to compare the effect of tangential vane direction on the atomization characteristics of the main-pilot nozzle configuration where swirl vanes of one nozzle is clockwise and another one is counter clockwise direction. Discharge coefficient, SMD distribution, velocity distribution and spray visualization are studied. For the current nozzle, flow rate of main nozzle was two times higher than pilot nozzle and it was found that for the pilot and main nozzles, injection pressure does not have a significantly affect the discharge coefficient. The experimental results indicate that the cone shaped pilot nozzle tip has better atomization than flat type pilot nozzle tip. Moreover, cone shaped pilot nozzle has wider spray angle than flat type nozzle. Clockwise swirl main nozzle provides smaller droplets and wider spray cone angle than clockwise swirl vane. It was also found that the when the counter swirl main nozzle is applied along with the pilot nozzle a wider spray angle and smaller droplets are expected in compare to that of the co-swirl nozzle. For main nozzle, liquid injection pressure had minor effects on the SMD distribution.