• Title/Summary/Keyword: Shape of Nozzle

Search Result 432, Processing Time 0.023 seconds

Evaluation of Formability of Copper Alloy for Regenerative Cooling Chamber before and after Heat Treatment (재생냉각 챔버 제작용 구리합금의 열처리 전후 성형성 평가)

  • Ryu, Chul-Sung;Lee, Keum-Oh;Choi, Hwan-Seok
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.37 no.12
    • /
    • pp.1201-1208
    • /
    • 2009
  • Dome stretching tests and tension tests were performed to evaluate the formability of a copper alloy used for manufacturing the regenerative cooling chamber. The test specimens were prepared to investigate the effect of heat treatment and direction of specimens on the formability. The test results show that forming limit values are increased by the heat treatment of the material but the variation of the forming limit values by manufacturing direction is negligible compared to the heat treatment effect, and forming limit values are also different according to the test methods. These results indicate that the high temperature heat treatment of the material before bulging is a very important process to deform the inner cylindrical structure of the regenerative cooling chamber into a nozzle shape by the bulging process without necking or fracture and the test methods also have a great effect on a evaluation of the formability. The forming limit diagram obtained in this study would be utilized to the design of regenerative cooling chamber nozzles.

Study of Optimal Process Conditions of 3D Porous Polymer Printing for Personal Safety Products (개인안전 제품을 위한 3 차원 다공성 폴리머 프린팅의 최적화 공정조건에 대한 연구)

  • Yoo, Chan-Ju;Kim, Hyesu;Park, Jun-Han;Yun, Dan-Hee;Shin, Jong-Kuk;Shin, Bo-Sung
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.33 no.5
    • /
    • pp.333-339
    • /
    • 2016
  • In this paper, a fundamental experiment regarding the formation of porous 3D structures for personal safety products using 3D PPP (Porous Polymer Printing) was introduced for the first time. The filament was manufactured by mixing PP (Polypropylene) and CBA (Chemical Blowing Agent) with polymer extruder, and the diameter of the filament was approximately 1.75mm. The proposed 3D PPP method, combined with the conventional FDM (Fused Deposition Modeling) procedure, was influenced by process parameters, such as the nozzle temperature, printing speed and CBA density. In order to verify the best processing conditions, the depositing parameters were experimentally investigated for the porous polymer structure. These results provide parameters under which to form a multiple of 3D porous polymer structures, as well as various other 3D structures, and help to improve the mechanical shock absorption for personal safety products.

Performance Analysis of Liquid Pintle Thruster Using Quasi-one-dimensional Multi-phase Reaction Flow: Part II. Thruster Performance Characteristics (준 일차원 다상 반응유동 기법을 이용한 케로신/과산화수소 액체 핀틀 추력기 성능해석 연구: Part II 추력기 성능 특성)

  • Kang, Jeongseok;Bok, Janghan;Sung, Hong-Gye;Kwon, Minchan;Heo, JunYoung
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.24 no.6
    • /
    • pp.78-84
    • /
    • 2020
  • The performance of pintle thruster is analyzed by using the pintle thruster performance analysis model which integrating the element models introduced in Part I. To verify the performance analysis, the results of the developed program are compared with the experimental data of kerosene/hydrogen peroxide liquid pintle thrusters. Based on the results, the characteristics of the pintle thruster are analyzed. The sensitivity analysis is performed to investigate the effect of thruster shape and operation parameters on performance characteristics using both OAT and scatter plot methods. The four performance parameters such as droplet diameter, film flow rate, O/F ratio, and nozzle throat diameter are evaluated to investigate their effects on characteristic speed, combustor pressure, and specific thrust.

Numerical Study on Thrust Characteristics of an External Pintle Thruster (노즐 목 외부형 핀틀추력기의 추력특성에 대한 수치해석 연구)

  • Choi, Junsub;Kim, Dongyeon;Huh, Hwanil
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.43 no.12
    • /
    • pp.1071-1078
    • /
    • 2015
  • Numerical computations were performed to investigate the effects of pintle stroke, altitude, and bore on the performance of an external pintle thruster. Results show that under-expansion flow occurs always, independent of pintle stroke. An external pintle thruster shows good performance in that it is capable of good amount of thrust control, while aerodynamic loads are increased due to shock waves on the pintle support. When altitude is increased to 20 km, the nozzle exit velocity, Mach number, thrust as well as aerodynamic loads are increased. Bore increases aerodynamic load 5.9%, and therefore pintle shape without bore is preferred for lower aerodynamic load of a pintle in order to actuate the pintle.

Flow characteristics of supersonic twin-fluid atomizers (초음속 2유체 분무노즐의 유동 특성)

  • Park, Byeong-Gyu;Lee, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.20 no.7
    • /
    • pp.2267-2276
    • /
    • 1996
  • Twin-fluid atomization has been widely used in combustors and process industries because of its high performance and simple structure. Flow visualization and pressure measurements were conducted to investigate the effects of gas flow in twin-fluid atomization. Schlieren photographs showed that changes in atomizing gas pressure, altered the wave patterns, and the lengths of both recitrculating toroid (impinging stangnation point) nad supersonic flow region in the jet. A longer supersonic wave pattern like net-shape wqas observed as atomizing gas pressure increased. The disintegration phenomenon of liquid delivery tube. The variation of spray angles with gas pressures were obtained by visualization using laser sheet beam. Suction pressuresat the nozzle orifice exit and recirculating region are shown to be used to estimate the stable atomization condition of a twin-fluid atomizer.

A Study of Spray Characteristics for the Slinger Injector System of Micro Turbo Jet Engine (초소형 터보제트엔진 슬링거 인젝터의 분무특성)

  • Choi, Hyun-Kyung;Choi, Seong-Man;Lee, Dong-Hun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2007.11a
    • /
    • pp.354-358
    • /
    • 2007
  • An experimental study was performed to understand spray characteristics of the slinger injector. system for the micro turbojet engine. In this fuel injection system, fuel is sprayed and atomized in the combustor by centrifugal forces of engine shaft. This experimental apparatus consist of a high speed rotating Spindle, slinger injector, pressure tank and acrylic case. The droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, the droplet size(SMD) is largely affected to rotational speed, mass flow rate and the number of injection orifice. From the this experimental study, we could understand the spray characteristics of the slinger injection system and obtain the optimum shape of the slinger injector nozzle which is suitable for the micro turbojet engine.

  • PDF

Design of Venturi Dump Surface for Pre-filming Airblast Injector (예막 공기충돌형 분사기의 벤추리 덤프면 설계)

  • Shin, Dongsoo;Choi, Myunghwan;Radhakrishnan, Kanmaniraja;Koo, Jaye;Jung, Seungchai
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.22 no.4
    • /
    • pp.44-54
    • /
    • 2018
  • In a spray experiment using a venturi mounted on a lean premixed LPP injector, droplets appear to have non-uniform distributions. To solve this problem, the exit angle of the venturi was changed to form a dump surface on the nozzle neck. The dump surface improved the atomization performance and minimized droplet loss while forming recirculation zone in the venturi exit. In order to solve the non-uniform spray of the injector, the flow characteristics inside the venturi and SMD of the spray are compared. Finally, an optimum venturi shape is selected to minimize the spray loss and improve the spray performance.

Local heat transfer measurement from a concave surface to an oblique impinging jet (오목한 표면위에 분사되는 경사충돌제트에 대한 국소열전달계수의 측정)

  • 임경빈;김학주
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.10 no.3
    • /
    • pp.324-333
    • /
    • 1998
  • Measurements of the local heat transfer coefficients on a hemispherically concave surface with a round oblique impinging jet were made. The liquid crystal transient method was used for these measurements. This method, which is a variation of the transient method, suddenly exposes a preheated wall to an impinging jet while video recording the response of liquid crystal for the surface temperature measurements. The Reynolds number used was 23,000 and the nozzle -to -jet distance was L/d=2, 4, 6, 8 and 10 and the jet angle was $\alpha$=0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$and 40$^{\circ}$. In the experiment, the maximum Nusselt number at all region occurred at L/d(equation omitted)6 and Nusselt number decreases as the inclined jet angle increases. For the normal jet the contours of constant Nusselt number are circular and as the jet is inclined closer and closer to the surface the contours become elliptical shape. The decreasing rate of the Nusselt number at X/d> 0(upstream) on a surface curvature are higher than those on a flate plate and the decreasing rate of the Nusselt number at X/d <0(downstream) on a surface curvature are lower than those on a flate plate. And also, the decreasing rate of local Nusselt number distribution at X/d <0(upstream) exhibit lower than with X/d <0(downstream) as jet angle increases. The second maximum Nusselt number occurred at long distance from stagnation point as jet angle increases.

  • PDF

A Study on the Encapsulation of Cosmetic Emulsion Using Microfluidics (Microfluidics를 이용한 화장품 에멀젼 캡슐레이션에 대한 연구)

  • Jeong, Nam-Gyun;Jin, Hong-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.22 no.1
    • /
    • pp.81-86
    • /
    • 2021
  • The cosmetic industry is technology-intensive in the field of fine chemistry and continues to grow globally. The functional aspects have been mainly emphasized in the past to increase the market share in these cosmetics industries. Recently, however, efforts have been made to attract the attention of consumers to the visual effects as well as the excellent performance of cosmetics at home and abroad. Accordingly, cosmetic manufacturers are trying various technologies that encapsulate the cosmetic emulsion and modify the shape, color, and texture of the emulsion capsule. The basic and easiest method of encapsulating emulsion is dropping the emulsion through the nozzle from emulsion storage. On the other hand, the existing method of encapsulating emulsion has a limit in reducing the size of the capsule. In this study, the limit was shown by theory and numerical analysis method, and the emulsion encapsulation phenomena occurring in the micro-channel were studied to apply microfluidics as an alternative.

An Experimental Study on Freezing Behavior of NaCl and Heavy Metal Aqueous Solution Using Freeze Concentration Method (동결농축법을 이용한 염수 및 중금속 수용액의 동결거동에 관한 실험 연구)

  • Kim, Jung-Sik;Lim, Seung-Taek;Oh, Cheol
    • Journal of Navigation and Port Research
    • /
    • v.37 no.2
    • /
    • pp.129-135
    • /
    • 2013
  • Recently, waste water treatment system is developed in small and middle size to get more economic advantage. Freeze concentration system has high thermodynamic efficiency and low energy consumption, can re-use purified water and cold energy obtained from ice. This study was experimentally performed to investigate pollution containment in frozen layer by cooling wall temperature, air-bubble flow methods, initial ice-lining thickness of frozen layer in NaCl aqueous solution and the representative heavy metals, Pb and Cr aqueous solution. As the result, a decrease in the cooling wall temperature bring a higher growth rate of ice front and the more solute was involved in frozen layer. The method to inject directly air-bubble into ice-liquid interface through ring shape nozzle gave high purity of ice compared to indirect method. Ice lining in 5mm thickness resulted in frozen layer with higher purity than 1mm thickness.