• Title/Summary/Keyword: Nozzle Pressure

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Thrust Vectoring Control of Supersonic Jet Using Proportional Control Valves (비례제어밸브를 이용한 초음속 제트의 추력편향 제어)

  • Lee, MyungYeon;Lee, Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.1
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    • pp.1-8
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    • 2019
  • An experimental study is performed to observe the characteristics of the thrust vectoring control (TVC) of the supersonic jet using proportional control valves. It is observed that three different TVC characteristics exist as the nozzle pressure ratio varies. Strong hysteresis phenomena are also observed during the valve control for a certain range of the nozzle pressure ratio. It is also noticed that the secondary chamber pressure is one of the influencing parameters for the TVC. Therefore, a control algorithm utilizing the secondary chamber pressure coefficient as a predictor is applied to achieve the stable TVC avoiding the hysteresis. Consequently, the stable TVC with the maximum deflection angle of about 20-degree has been realized using the proportional control valves.

Behaviors of Mach Disk in Underexpanded Supersonic Moist Jet (초음속 습공기 제트에서 발생하는 마하디스크의 거동)

  • 백승철;김희동;권순범
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.87-90
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    • 2003
  • It has been well known that the major feature of compressible flow fields might be different depending on their formation processes. The objectives of the present study is to investigates the effect of jet development on the time history of supersonic jet flow field, accompanying nonequilibrium condensation. Especially, the behaviors of Mach disk diameter and location in a supersonic moist air jet are presented in terms of nozzle pressure ratio and initial relative humidity. The relative humidity of moist air is controlled at the nozzle supply, and the nozzle pressure ratio is varied to obtain the moderately underexpanded flows at the exit of the nozzle, installed in an indraft wind tunnel. It is found that at the same pressure ratio the Mach disk diameter increases with the initial relative humidity, while moves further upstream. Furthermore, the values of Mach disk diameter and location for increasing pressure ratio show larger than those for increasing.

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An Experimental Study on Noise Phenomena in Supersonic Over-expanded Jet (초음속 과팽창 제트에서 발생하는 소음현상에 관한 실험적 연구)

  • Kweon Yong-Hun;Lim Chae-Min;Kim Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.337-340
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    • 2006
  • The present paper describes an experimental work to investigate a transonic resonance in supersonic jet that is discharged from a convergent-divergent nozzle. When the nozzle m: at low nozzle pressure ratios, the shock occurs within the divergent section of the nozzle. The transonic resonance of a jet flow is generated by an emission of strong acoustic tones due to the unsteadiness of the shock. A Schlieren optical system is used to visualize the supersonic jet flow In order to specify the flow resonance of a jet, acoustic measurements are performed to obtain noise spectra. The acoustic characteristics of transonic resonace are compared with those of screech tones. The results obtained show that unlike screech frequency, the transonic reso- nace frequency somewhat increases with increasing the nozzle pressure ratio.

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A Theoretical Study on the Fluid-Structure Interaction Due to the Pump in the Pressurized Water Reactor (원자로에서 펌프에 의해 야기되는 유체와 구조물 상호 작용에 대한 이론적 연구)

  • Lee, Kye-Bock;Jong Ryul park
    • Nuclear Engineering and Technology
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    • v.27 no.5
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    • pp.710-720
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    • 1995
  • The propagation of pump-induced pressure pulsation in a reactor is important because of the potential for vibration and resultant damage of reactor internals. A hydrodynamic model has been developed to obtain the pressure fluctuation due to the operation of pumps in the annulus(between the core support barrel and reactor vessel of a pressurized water reactor) including the coolant inlet pipe. The mathematical analysis is formulated in accordance with the linearized Navier-Stokes equation by assuming a compressible, inviscid flow. Two regions are considered separately and by coupling the solutions of the inlet pipe and the annulus, the inlet nozzle pressure(pressure at pipe and annulus interface) is to be calculated without assumptions. The geometric parameter effect on the pump-induced pressure pulsation is evaluated. Comparison of predicted and measured inlet nozzle pressure values for each forcing frequency shows good order of magnitude agreement.

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Numerical Study on Under-Expanded Jets through a Supersonic Nozzle(II) (초음속 노즐을 통하는 부족팽창 제트에 관한 수치계산적 연구 (2))

  • Kim, Hui-Dong;Sin, Hyeong-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.6
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    • pp.1994-2004
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    • 1996
  • Numerical calculation was applied to supersonic under-expanded jets, and compared with the results of a linear theory and other experiments. TVD difference scheme was employed to solve 2-dimensional and axisymmetric inviscid Euler equation. This paper aims to explore the effects of angle of divergence and design Mach number of nozzle on the structure of under-expanded jets. The angle of divergence was varied from 0 to 20 deg. The results show that the length of the first cell of the under-expanded jets decreases and Mach disk generates at lower nozzle pressure ratio, if the angle of divergence or design Mach number of nozzle increases. The distance from the nozzle exit to Mach disk in 2-dimensional jets becomes much larger than that of axisymmetric jets, and the widths of the jet boundary and the barrel shock wave are also larger than that of axisymmetric jets. Calculation results indicate that the configuration of the under-expanded jets is strongly dependent on the nozzle pressure ratio.

An Experimental Study on Supersonic Jet Issuing from Gas Atomizing Nozzle (I) (가스 미립화용 노즐로부터 방출되는 초음속 분류에 관한 실험적 연구)

  • Kim, Hui-Dong;Lee, Jong-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.2
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    • pp.697-709
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    • 1996
  • Supersonic axisymmetric jets issuing from various kinds of nozzles with a throat diameter of a few millimeters were experimentally investigated. The exit Mach number and Reynolds number based on the throat diameter of nozzle were in the range of 1.0 ~ 5.9 and 8.4$\times$ $10^4$ ~ 2.9$\times$$10^6$, respectively. The nozzle pressure ratio was varied from 5 to 85. Present paper aims to offer fundamental information of the supersonic free-jets, with an emphasis to give data with which the shape of the free-jets can be depicted under a specified condition. Experimental data are summarized to enable an estimation of the shape of the supersonic free-jets. The result shows that the shape of free-jets is dependent on only the nozzle pressure ratio.

Preparation and evaluation of GFP-containing microspheres for oral vaccine delivery system (경구용 백신수송체용 GFP 함유 마이크로스피어의 제조 및 평가)

  • Jiang, Ge;Park, Jong-Pil;Kwak, Son-Hyok;Hwang, Sung-Joo;Maeng, Pil-Jae
    • Journal of Pharmaceutical Investigation
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    • v.30 no.4
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    • pp.253-258
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    • 2000
  • In order to design the oral vaccine delivery system, we prepared the alginate micro spheres containing GFP (green fluorescent protein) as a model drug by spray method. To optimize the preparation conditions of microspheres, we investigated the effects of various parameters including nozzle pressure, nozzle opening angle, and concentrations of sodium alginate and calcium chloride. The prepared microspheres were evaluated by measuring their sizes, loading efficiency, and morphology. The particle size of microspheres was affected by the concentration of sodium alginate and calcium chloride, nozzle pressure, and nozzle opening angle. As the concentration of sodium alginate increased, GFP loading efficiency and particles size of microsphere also increased. However, it was observed to be difficult to spray the sodium alginate solution with concentration greater than 1.5% (w/v), due to high viscosity. The pressure over $3\;kgf/cm^2$ didn't affect the size of particles. As a result, the spraying method enabled us to prepare microspheres for oral vaccine delivery system. In this study, microspheres prepared with 1% (w/v) sodium alginate had greater loading efficiency and better spherical shape.

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Experimental Investigations Into Low Current Steady State Arcs In A Dual-Airflow Model Interrupter

  • Shin, Young-June;Cho, Yun-Ok;Kim, Jin-Gi;Lee, Jeong-Rim
    • Proceedings of the KIEE Conference
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    • pp.961-965
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    • 1992
  • It is well-known that shock waves frequently occur inside the nozzle of the interrupter, and that they play important roles in the arc interruption. A model interrupter with two-dimensional dual-airflow nozzles was used for this experiment. The arc was ignited with 1.4 mil copper wire stretched between the electrodes which were spaced out 56 mm. The arc current of 60 to 230 A was achieved by adjusting the external resistance from 5.5 to 1.6 ohms. The arc tests have been conducted for investigating the air arc characteristics, and the effects of shock waves and nozzle pressure ratios on the arc voltage, the arc resistance, the arc power, and average electric field. The results of these tests have been analyzed to provide insights into the arc characteristics for gas circuit breakers. The average electric field is represented by the function of the arc current to show the negative E-I characteristic explicitly. The effects of shock waves and nozzle pressure ratios are shown to be significant for a circuit breaker performance.

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An Experimental Study of Underexpanded Moist Air Jet Impinging on a Flat Plate

  • Lee, D.W.;S.C. Baek;S.B. Kwon;Kim, H.D.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.768-773
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    • 2004
  • When a gas expands through a convergent nozzle in which the ratio of the ambient to the stagnation pressures is higher than that of the critical one, the issuing jet from the nozzle is underexpanded. If a flat plate is placed normal to the jet at a certain distance from the nozzle, a detached shock wave is formed at a region between the nozzle exit and the plate. In general, supersonic moist air jet technologies with nonequilibrium condensation are very often applied to industrial manufacturing processes. In spite of the importance in major characteristics of the supersonic moist air jets impinging to a solid body, its qualitative characteristics can not even know. In the present study, the effect of the nonequilibrium condensation on the underexpanded moist air jet impinging on a vertical flat plate is investigated experimentally. Flow visualization and impact pressure measurement are performed for various relative humidities and flat plate positions. The obtained results show the plate shock and Mach disk are dependent on the nozzle pressure ratio and the relative humidity, but for a given nozzle pressure ratio, the diameters of the plate shock and Mach disk depend on the stagnation relative humidity. The impact pressure deviation from the flow of without condensation is large, as the relative stagnation humidity increases.

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Enlarge duct length optimization for suddenly expanded flows

  • Pathan, Khizar A.;Dabeer, Prakash S.;Khan, Sher A.
    • Advances in aircraft and spacecraft science
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    • v.7 no.3
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    • pp.203-214
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    • 2020
  • In many applications like the aircraft or the rockets/missiles, the flow from a nozzle needs to be expanded suddenly in an enlarged duct of larger diameter. The enlarged duct is provided after the nozzle to maximize the thrust created by the flow from the nozzle. When the fluid is suddenly expanded in an enlarged duct, the base pressure is generally lower than the atmospheric pressure, which results in base drag. The objective of this research work is to optimize the length to diameter (L/D) ratio of the enlarged duct using the CFD analysis in the flow field from the supersonic nozzle. The flow from the nozzle drained in an enlarged duct, the thrust, and the base pressure are studied. The Mach numbers for the study were 1.5, 2.0 and 2.5. The nozzle pressure ratios (NPR) of the study were 2, 5 and 8. The L/D ratios of the study were 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. Based on the results, it is concluded that the L/D ratio should be increased to an optimum value to reattach the flow to an enlarged duct and to increase the thrust. The supersonic suddenly expanded flow field is wave dominant, and the results cannot be generalized. The optimized L/D ratios for various combinations of flow and geometrical parameters are given in the conclusion section.