• Journal of ILASS-Korea
• /
• v.5 no.3
• /
• pp.27-36
• /
• 2000

In this study, spray characteristics of a dual airblast atomizer are addressed. Three dimensional characteristics of a dual airblast atomizer with air swirl are measured to provide the significant data. The liquid flow rate was fixed at 0.06 kg/min, and atomizing air was controlled at the liquid-air mass ratio of 4.0. The performance of the spray with co-swirl and counter-swirl flow was investigated at each point in the developed spray region using a three-component phase Doppler particle analyzer. This instrument was also used to evaluate the concentration profiles. The three dimensional mean velocity were investigated of present flow characteristics of the dual airblast atomizer. In addition, drop size distributions, mean droplet size profile, and droplet concentration were analyzed to understand atomization characteristics. This experimental results can be conveniently utilized for the preliminary design of gas turbine engines for aircraft.

• Journal of Institute of Convergence Technology
• /
• v.3 no.2
• /
• pp.51-56
• /
• 2013

This paper describes the atomization characteristics, as well as the velocity and size distribution, of DME spray based on common-rail injection system. To analyze the possibility of using DME fuel as an alternative fuel of diesel, spray atomization characteristics were investigated. For this investigation, two-dimensional phase Doppler analyzer system was used to obtain droplet size and velocity distribution simultaneously. Velocity and droplet size measurements were performed at various injection pressures. Results showed that increasing pressure from 25MPa to 50MPa leads to higher spray droplet velocities and smaller droplet diameter but injection pressure above 40MPa, no signifiant reduction was observed. With the droplet velocity and SMD comparison between diesel and DME fuel, it can be observed that DME has smaller SMD and droplet velocity due to its low surface tension.

• Journal of Mechanical Science and Technology
• /
• v.16 no.8
• /
• pp.1135-1143
• /
• 2002

The intermittent spray characteristics of the single-hole diesel nozzle (d$\sub$n/=0.32 mm) used in the fuel injection system of heavy-duty diesel engines were experimentally investigated. The mean velocity and turbulent characteristics of the diesel spray injected intermittently into the still ambient were measured by using a 2-D PDPA (phase Doppler particle analyzer) . The gradient of spray half-width linearly increased with time from the start of injection, and it approximated to 0.04 at the end of the injection. The axial mean velocity of the fuel spray measured along the radial direction was similar to that of the free air jet within R/b= 1.0-1.5 regardless of elapsing time, and its non-dimensional distribution corresponds to the theoretical velocity distributions suggested by Hinze in the downstream of the spray flow fields. The turbulent intensity of the axial velocity components measured along the radial direction represented the 20-30% of the U$\sub$cι/ and tended to decrease in the outer region. The turbulent intensity in the trailing edge was higher than that in the leading edge.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.801-806
• /
• 2000

This experimental study is to investigate the intermittent spray characteristics of a multi-hole nozzle in a heavy-duty DI diesel engine. Multi 8 hole$(d_n=0.25mm)$, Multi 3 hole$(d_n=0.42)$ and Sing hole nozzle$(d_n=0.25mm)$ were used in this experiment. By using the 2-D PDPA(phase Doppler particle analyzer), the droplet diameter and the velocity of a diesel spray injected intermittently from the multi and the single-hole nozzle into a still ambient were measured. In order to calculate the mean values such as mean velocity, SMD, AMD etc. and to analyze the intermittent characteristics, the time-window of 0.15ms were applied. In the spray, the small droplet$(D<10{\mu}m)$ was regarded as an air flow, and the correlation between the fuel droplet$(10{\mu}m and the air (low was examined. The normalized axial droplet-air relative velocity of the 8 hole, the 3 hole and the single hole nozzle was evaluated as 0.081, 0.067, 0.06 and in case of the radial droplet-air relative velocity, the normalized. value is 0.014, 0.013 and 0.008 respectively.

• Journal of ILASS-Korea
• /
• v.2 no.3
• /
• pp.17-24
• /
• 1997

A simplified experiment was performed to figure out the atomization characteristics of rice-bran oil which it is highly viscous liquid by applying ultrasonic energy. A spray system, an ultrasonic system, and three kinds of hole-type nozzles(hole diameter: 0.31, 0.34, 0.37mm) 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 measurement and calculation of spray droplets data. Nozzle opening pressures were chosen of 3 levels, i.e, 16, 20, and 24MPa. As a result, it could be concluded that the ultrasonic energy was effective to improve the spray atomization when it 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 method compared with the conventional spray increased about 15% in the case of hole type nozzles. By increasing of the nozzle opening pressure and decreasing of the hole diameter, the atomization of spray droplets was improved.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.13 no.6
• /
• pp.41-47
• /
• 2009

This paper presents the spray characteristics of the simplex fuel nozzle with different working fluids for the gas turbine engine. Spray characteristics can be changed with viscosity, surface tension and density. In this research, water and test fluid type 2 which has similar characteristics of the kerosene are used as a working fluid. Spray visualization was performed by using ND-Yag laser and droplet size was measured by using PDPA(Phase doppler particle analyzer) system. The test results show that spray shapes and SMD distributions of two working fluids are similar at main spray region.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.4 no.1
• /
• pp.36-45
• /
• 2000

Most researches for impinging jet spray have been focused on under-standing the breakup mechanism of a liquid sheet formed by the collision of jets and modeling the spray breakup using experimental data. For this reason, there have been few studies on the characteristics of the spatial spray distribution which affects significantly the combustion efficiency. Hence, we measured the radial distribution of fuel massflux using a like-doublet type injector. Instead of PDPA(Phase Doppler Particle Analyzer) which has been used only for the point measurement of the drop size of spray, PLIF(Planar Laser Induced Fluorescence) technique was developed lot the 2-D measurement of the massflux distribution of spray Indirect photography technique was also used to verify PLIF data.

• Nuclear Engineering and Technology
• /
• v.56 no.7
• /
• pp.2545-2556
• /
• 2024

In the present study, we investigated the velocity distribution, temperature distribution and condensation characteristics of steam jet issuing from four different orifice nozzles with a Reynolds number of approximately 79,000 using the phase Doppler particle analyzer system and a K-type thermocouple. The steam jet discharged from the orifice nozzle has a wider jet width compared to pipe nozzle because of the vena-contracta which can enhance the mixing of steam jet with the ambient air. Therefore, the orifice jet showed less condensation due to its wideness, resulting in small velocity decay rate and large temperature decay rate due to momentum conservation and decreased latent heat release compared to pipe nozzle, respectively. Also, the wider jet width of the orifice jet resulted in larger velocity and temperature spread rate compared to the pipe jet. In addition, the increase in the aspect ratio of the orifice jet led to more condensation and larger velocity spread rate and temperature spread rate due to both the vena-contracta and axis-switching effect, resulting in the increase of jet entrainment.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.11a
• /
• pp.254-259
• /
• 1996

Phase Doppler particle analyze. (PDPA) is a instrument which can be used to obtain simultaneous size and velocity measurements in a multiphase flow. In this study, the size of the water droplets entrained from a bubbling surface of a stagnant liquid column is measured by PDPA with a specially designed transmitter of long focal length and large beam diameter. The test section tube is made of acryle with 18 mm I.D. and 900 mm length. The experimental data are obtained for the air superficial velocity between 0.7 m/s to 3.4 m/s at atmospheric pressure. The experimental results show that there exists large difference in the entrainment mechanism between the churn-turbulent flow and annular flow. Through the present study, the phase Doppler analyzer system is shown to be successfully applied to measure particle sizes larger than $2,000\mu\textrm{m}$ if a transmitter of long focal length is utilized.

• Journal of Mechanical Science and Technology
• /
• v.14 no.4
• /
• pp.466-476
• /
• 2000

This paper presents atomization characteristics of a double impinging F -0-0- F type injector with four streams. A phase Doppler particle analyzer was employed to measure the droplet-size and water was used as the inert simulant liquid instead of reactive propellant liquids. The droplet mean diameter (SMD) and size distribution were measured to investigate the effects of the momentum ratio and pressure drop variations. This experimental results can be used during the preliminary design stage of a impinging stream type injector for liquid rockets.