• 제목/요약/키워드: Nozzle Pressure

검색결과 83건 처리시간 0.431초

An Experimental Study of the Trust Vector Control Using Counterflow Concept

  • C. M. Lim;Kim, H. D.;Lee, K. H.;T. Setoguchi
    • 한국추진공학회:학술대회논문집
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    • pp.192-197
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    • 2004
  • Recently, fluidic thrust vectoring methods have been preferably employed to control the movement of propulsive systems due to relatively simpler design and lower cost than mechanical thrust vectoring methods. For An application of the thrust vectoring to flight bodies, it is necessary to understand very complicated exhaust flows which are often subject to shock waves and boundary layer separation. But researches for the thrust vector control using counterflow have been few. In the present study, experiments have been performed to investigate the characteristics of supersonic jets controlled by a thrust vectoring method using counterflow. The primary jet is expanded through a two-dimensional primary nozzle shrouded by collars, and is deflected by the suction of the air near nozzle into an upper slot placed between the primary nozzle and the upper collar. A shadowgraph method is used to visualize the supersonic jet flowfields. Primary nozzle pressure ratios and suction nozzle pressure ratios are varied from 3.0 to 5.0, and from 0.2 to 1.0 respectively. The present experimental results showed that, for a given primary nozzle pressure ratio, a decrease in the suction nozzle pressure ratio produced an increased thrust vector angle. As the suction nozzle pressure ratios were increased and decreased, the hysteresis of the thrust vectoring was observed through the wall pressure distributions

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Counterflow 개념을 이용한 추력벡터 제어에 관한 실험적 및 수치해석적 연구 (Experimental and Computational Studies of the Fluidic Thrust Vector Control Using a Counterflow Concept)

  • 임채민;이권희;김희동
    • 대한기계학회:학술대회논문집
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    • pp.1637-1642
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    • 2004
  • Experimental and computational studies were performed to investigate the effectiveness of a thrust vectoring method using a counterflow concept. A shadowgraph method was used to visualize the supersonic jet expanded from a two-dimensional convergent-divergent nozzle and deflected by a now suction. The primary nozzle pressure and suction nozzle pressure ratios are varied between 3.0 and 5.0, and between 0.2 and 1.0 respectively. The present experimental and computational results showed that, for a given primary nozzle pressure ratio, a decrease in the suction nozzle pressure ratio produced an increased thrust vector angle, and during the change processes of the suction pressure, a hysteresis effect of the thrust vectoring was found through the wall pressure distributions.

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핀틀 변곡 각도에 따른 E-D 노즐 특성에 대한 전산수치해석 연구 (Numerical Study on an E-D Nozzle Characteristics with Various Pintle Inflection Angles)

  • 박상현;문태석;허환일
    • 한국추진공학회지
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    • v.22 no.6
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    • pp.19-27
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    • 2018
  • 본 논문에서는 E-D 노즐 공압 실험 연구의 선행 연구로써, 노즐 압력비에 따라 변화하는 E-D 노즐특성 파악을 위한 해석적 연구가 수행되었다. 설계 변수 중, 핀틀 변곡 각도를 하나의 변수로 하여 서로 다른 세 가지 수치해석 모델을 설계하였다. 노즐 압력비가 낮을 때는 E-D 노즐 내부로 외부 대기가 유입되어 개방 유동장이 형성되었다. 노즐 압력비가 높아짐에 따라 노즐 내부에 재순환 영역이 고립되는 폐쇄 유동장으로 유동 천이가 발생함을 확인하였다. 또한, 전체 노즐 압력비 구간에서 핀틀 변곡 각도가 높은 해석 모델에서 가장 높은 추력 계수가 도출되었다.

노즐 압력비와 충돌면까지의 거리 변화에 따른 초음속 충돌 제트 유동의 진동 특성 (Oscillatory Features of Supersonic Impinging Jet Flows; Effects of the Nozzle Pressure Ratio and Nozzle Plate Distance)

  • 김성인;박승오;이광섭
    • 한국전산유체공학회:학술대회논문집
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    • pp.154-159
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    • 2004
  • Numerical simulations of supersonic impinging jet flows are carried out using the axisymmetric Navier-Stokes code. This paper focuses on the oscillatory flow features associated with the variation of the nozzle pressure ratio and nozzle-to-plate distance. Frequencies of the surface pressure oscillation from computational results are in accord with the measured impinging tones for various cases of nozzle-to-plate distance. The variation of this frequency with distance show a staging behavior. Computed results for the case of nozzle pressure ratio variation for a fixed nozzle-to-plate distance also demonstrate a staging behavior. These two seemingly different staging behaviors are found to obey the same frequency-distance characteristics when the frequency and the distance are normalized by using the length of the shock cell.

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고속 회전하는 RAP(Rocket Assisted Projectile)의 추력 및 유동 특성에 관한 연구 (A Study on the Thrust and Flow Characteristics of High Spin RAP(Rocket Assisted Projectile))

  • 반영우;정현호;박주현;주형욱;이치훈;박용인;윤종원
    • 한국추진공학회:학술대회논문집
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    • pp.1072-1076
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    • 2017
  • 고속 회전하는 로켓보조추진탄의 로켓 추진 유동특성을 수치해석적으로 연구하였다. 회전지상연소시험을 통해 연소실 내부 압력을 계측하였고 지상 조건, 작동 고도 조건, 기저부 압력 조건의 노즐압력비를 적용하여 수치해석을 수행하였다. 그리고 수치해석 결과를 등엔트로피 1차원 해와 지상회전시험 결과와 비교 하였다. 또한 동일 노즐압력비에서 유동의 회전 유/무에 따른 추력특성의 차이를 확인하였다.

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렌즈 사출성형 공정 상태 특징 추출 및 진단 알고리즘의 개발 (A Development of Feature Extraction and Condition Diagnosis Algorithm for Lens Injection Molding Process)

  • 백대성;남정수;이상원
    • 한국정밀공학회지
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    • v.31 no.11
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    • pp.1031-1040
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    • 2014
  • In this paper, a new condition diagnosis algorithm for the lens injection molding process using various features extracted from cavity pressure, nozzle pressure and screw position signals is developed with the aid of probability neural network (PNN) method. A new feature extraction method is developed for identifying five (5), seven (7) and two (2) critical features from cavity pressure, nozzle pressure and screw position signals, respectively. The node energies extracted from cavity and nozzle pressure signals are also considered based on wavelet packet decomposition (WPD). The PNN method is introduced to build the condition diagnosis model by considering the extracted features and node energies. A series of the lens injection molding experiments are conducted to validate the model, and it is demonstrated that the proposed condition diagnosis model is useful with high diagnosis accuracy.

Mixer-Ejector 노즐 유동장에 관한 수치해석 (Computational Analysis of the Flowfield of a Mixer-Ejector Nozzle)

  • Park, Yun-Ho
    • 한국추진공학회지
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    • v.6 no.1
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    • pp.71-82
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    • 2002
  • 본 연구에서는 2차원의 압축성 Navier-Stokes 코드를 개발하여 mixer-ejector 노즐의 유동장 해석을 다양한 덕트와 노즐 면적비 및 노즐 압력비에 대하여 계산을 수행하였다. 덕트와 노즐 면적비 계산에서는 먼저 효율적인 2차 유동의 유입을 위한 최적의 면적비가 있음을 볼 수 있었다. 높은 면적비에서는 입구 자유유동의 적절한 혼합없이 mixing duct를 그대로 통과하는 것을 볼 수 있었고, 낮은 면적비에서는 제트의 경계가 유입 유동에 장애물로 작용하는 것을 볼 수 있었다. 노즐 압력비의 계산에 있어서는 shroud 벽면과 shock cell structure 간에 상호작용이 작다면 유입유량은 압력비에 따라 증가하는 것을 볼 수 있었다.

An Experimental Study on the Characteristics of Rectangular Supersonic Jet on a Flat Plate

  • Kwak, Ji-Young;Lee, Yeol
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.324-331
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    • 2016
  • The present study focuses on the characteristics of a supersonic jet flowing from a rectangular nozzle exit on a flat plate. Flow visualization techniques using schlieren and kerosene-lampblack tracing are utilized to investigate shock reflection structures and boundary-layer separations over a flat plate. Wall pressure measurements are also carried out to quantitatively analyze the flow structures. All observations are repeated for multiple jet flow boundary conditions by varying the flap length and nozzle pressure ratio. The experimental results show that the jet flow structures over the flat plate are highly three-dimensional with strong bleeding flows from the plate sides, and that they are sensitive to plate length and nozzle pressure ratio. A multi-component force measurement device is also utilized to observe the characteristics of the jet flow thrust vectoring over the plate. The maximum thrust deflection angle of the jet is about $8^{\circ}$, demonstrating the applicability of thrust vector control via a flat plate installed at the nozzle exit.

밀폐된 노즐 내부의 초기 압력발달에 대한 수치적 연구 (Numerical study of interior pressure development of closed nozzle)

  • 박근홍;김형준;권세진
    • 한국추진공학회:학술대회논문집
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    • v.y2005m4
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    • pp.423-426
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    • 2005
  • 본 연구에서는 노즐 마개에 의해 출구가 막힌 노즐 내부의 압력 발달을 관찰하기 위하여 밸브 작동을 고려한 수치해석을 수행하였다. 밸브가 작동함에 따라 시간에 대하여 압력값을 실험결과와 비교하였다. 수치해석에는 상용코드가 사용되었으며, 밸브 작동을 고려한 경계조건을 이용한 해석 결과는 실험결과와 비교적 잘 일치하는 경향을 보여준다.

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인공위성 추력기의 유동 해석 (Flow Computation of a Satellite Thruster)

  • 권순덕;김성초;김정수;최종욱;박정
    • 한국가시화정보학회:학술대회논문집
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    • pp.145-148
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    • 2006
  • In order to design a micro-thruster which controls the altitude of a space vehicle for a very long lifetime, the flow field should be analyzed considering the nozzle geometry and the difference between stagnation and environmental pressures and so on. This paper describes the axisymmetric non-reacted computational results which were carried out to understand the basic flow phenomena according to the high nozzle pressure ratio. The area ratio is about 56 and the diameter of a nozzle exit is about 0.46 inch. The Mach cell and waves are predicted well.

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