• Title/Summary/Keyword: Driving nozzle

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Design Factor Analysis of Aerospike Pintle Nozzle for Increasing Thrust in Off-Design (탈설계 조건에서 추력 증대를 위한 에어로 스파이크 핀틀 노즐의 설계인자 분석 연구)

  • Kim, Jeongjin
    • Journal of Aerospace System Engineering
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    • v.16 no.4
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    • pp.1-9
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    • 2022
  • A design factor analysis was conducted to reduce the thrust reduction in the off-design, due to the driving of the aerospike pintle nozzle. The close (NPR 100) as well as the open (NPR 11) stroke were fixed, as under-expansion conditions. The pintle contour, pintle head radius (R), cowl angle (θ), and cowl exit length (L) were selected as design factors. The change in thrust was analyzed, using a verified numerical analysis technique. First, the pintle head radius and the length of the cowl exit had little influence on the thrust. The cowl angle changed the mass flow rate by affecting the effective nozzle throat area, and created a reverse pressure gradient at the cowl exit. As a result of applying the dual aerospike contour, it was confirmed that the thrust in the design-off increased by approximately 1.2%, compared to the reference case and by approximately 3.4% compared to the worst case.

Analysis of Macroscopic Spray Characteristics of Diesel Injectors with Three Different Needle Driving Type in Common Rail Direct Injection System (3가지 니들구동방식별 CRDi 디젤엔진용 고압 인젝터의 거시적 분무특성 비교해석)

  • Lee, Jin-Wook;Min, Kyoung-Doug
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.3
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    • pp.351-358
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    • 2006
  • The capability of high pressure injection with small fuel quantify at all engine operating conditions is one of the main feature in common rail fuel injection system, which is used in small and light-duty Diesel engine. The key parameter for the better atomized fuel sprays and multiple injections of this common rail fuel injection control, that can be freely selected irrespective of the engine speed and load is the mechanism controlling the needle energizing and movement in high pressure Diesel injector. In the electro-hydraulic injector, the injection nozzle is being opened and closed by movement of the injector's needle which is balanced by pressure between the nozzle seat and the needle control chamber. This study describes the macroscopic spray structure characteristics of the common rail Diesel injectors with different electric driving method i.e. the solenoid-driven and piezo-driven type. The macroscopic spray characteristics such as spray tip speed. spray tip penetration and spray cone angle were investigated by the high speed spray, which is measured by the back diffusion light illumination method with optical system for the high speed temporal photography in a constant volume chamber pressurized by nitrogen gas. As the results, the prototype piezo-driven injector system was designed and fabricated for the first time in domestic case and the effect of injector's needle response driven by different drive type was compared between the solenoid and piezo-driven injector It was found therefore. that the piezo-driven injector showed faster needle response and had better needle control capability by altering the electric input value than the solenoid-driven injector.

Analysis of Hydraulic Characteristics of Two Solenoid-driven Injectors for CRDi System (2개 솔레노이드 구동방식별 CRDi용 인젝터의 유압 동특성 해석)

  • Lee, Jin-Wook;Lee, Jung-Hyup;Kim, Min-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.6
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    • pp.140-147
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    • 2011
  • The injection nozzle of an electro-hydraulic injector for the common rail Diesel fuel injection system is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the slenoid actuator was considered as a prime movers in high pressure Diesel injector. Namely a solenoid-driven Diesel injector with different driving current types, as a general method driven by solenoid coil energy, has been applied with a purpose to develop the analysis model of the solenoid actuator to predict the dynamics characteristics of the hydraulic component (injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the solenoid-driven injector, the circuit model has been developed as a unified approach to mechanical modeling in this study. As this analytic results, we know the suction force and first order time lag for driving force can be endowed in solenoid-driven injector in controlling the injection rate. Also it can predict that the input current wave exerted on solenoid coil is the dominant factor which affects on the initial needle behavior of solenoid-driven injector than the hydraulic force generated by the constant injection pressure.

Study of HSDI Diesel Engine Development for Low Fuel Consumption (HSDI 디젤 엔진 연비 저감 개발에 대한 연구)

  • Chun, Je-Rok;Yu, Jun;Yoon, Kum-Jung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.1
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    • pp.138-143
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    • 2006
  • Modification of injector, oil ring tension reduction and oil pump rotor re-matching with optimization of relevant engine control parameters could drive fuel consumption reduction of HSDI diesel engine. A 5 holes injector was replaced with a 6 holes with smaller nozzle hole diameter and 1.5 k factor, and evaluated in a view of fuel economy and emission trade-offs. With introducing smaller nozzle hole diameter injector, PM(Particulate Matter) was drastically decreased for low engine load and low engine rpm. Modification of oil pump and oil ring was to reduce mechanical friction and be proved to better fuel economy. Optimization of engine operating conditions was a great help for the low fuel consumption. Influence of the engine operating parameters· including pilot quantity, pilot interval, air mass and main injection timing on fuel economy, smoke and NOx has been evaluated with 14 points extracted from NEDC(New European Driving Cycle) cycle. The fuel consumption was proved to $7\%$ improvement on an engine bench and $3.7\%$ with a vehicle.

Heat Transfer on a Jet Vane Surface Installed in a Rocket Nozzle (로켓노즐에 장착된 제트베인 표면의 열전달 특성)

  • Yu Man Sun;Cho Hyung Hee;Hwang Ki Young;Bae Ju Chan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.1
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    • pp.9-16
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    • 2005
  • Jet vane is an useful component which is installed at the end of a nozzle for the purpose of the posture control and the secure controlling stability during the initial launching of a rocket. During several seconds from its initial launching moment, the JV driving part is heated due to the direct contact of the vane with the combusted gas and the vane is ablated mechanically or chemically. In this study, as the fundamental study for the thermal analysis of jet vane, the heat transfer into a jet vane which is located in the uniform supersonic flow field is calculated. For this, boundary layer integral method and finite difference method are used simultaneously. Based on the thermal boundary conditions derived from the analysis, the transient heat conduction in the vane is also calculated.

Optimization of ejector for swirl flow using CFD (CFD를 이용한 회전 운동을 하는 이젝터의 최적화)

  • Kang, Sang-Hoon;Park, Young-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.2
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    • pp.31-37
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    • 2017
  • This paper investigates the effect of the rotational motion of a driving fluid generated by a rotational motion device at the inlet of a driving nozzle for a gas-liquid ejector, which is the main device used for ozonated ship ballast water treatment. An experimental apparatus was constructed to study the pressure and suction flow rate of each port of the ejector according to the back pressure. Experimental data were acquired for the ejector without rotational motion. Based on the data, a finite element model was then developed. The rotational motion of the driving fluid could improve the suction efficiency of the ejector based on the CFD model. Based on the CFD results, structure optimization was performed for the internal shape of the rotation induction device to increase the suction flow rate of the ejector, which was performed using the kriging technique and a metamodel. The optimized rotation induction device improved the ejector efficiency by about 3% compared to an ejector without rotational motion of the driving fluid.

Design Study of a Simulation Duct for Gas Turbine Engine Operations (가스터빈엔진을 모의하기 위한 시뮬레이션덕트 설계 연구)

  • Im, Ju Hyun;Kim, Sun Je;Kim, Myung Ho;Kim, You Il;Kim, Yeong Ryeon
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.1
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    • pp.124-131
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    • 2019
  • A design study of gas turbine engine simulation duct was conducted to investigate the operating characteristics and control gain tunning of the Altitude Engine Test Facility(AETF). The simulation duct design involved testing variable spike nozzle and ISO standard choking nozzle to verify the measurements such as mass flow rate and thrust. The simulation duct air flow area was designed to satisfy Ma 0.4 at the aerodynamic interface plane(AIP) at engine design condition. The test conditions for verifying the AETF controls and measurement devices were deduced from 1D analysis and CFD calculation results. The spike-cone driving part was designed to withstand the applied aero-load, and satisfy the axial traversing speed of 10 mm/s at whole operation envelops.

Driving Per Nozzle By Various Waveform Depending On Resonance Frequency In Piezoelectric Inkjet Head (잉크젯 헤드의 공진주파수에 따른 구동파형을 이용한 개별노즐 제어)

  • Kim, Y.J.;Park, C.S.;Sim, W.C.;Kang, P.J.;Yoo, Y.S.;Park, J.H.;Joung, J.W.;Oh, Y.S.
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1542-1543
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    • 2007
  • This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Using the water based ink of viscosity of 11.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets through 64 nozzles average velocity of 4.05 m/s with standard deviation of 0.06 m/s and average diameter of $29.2\;{\mu}m$ with standard variation of $0.5\;{\mu}m$.

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A Numerical Analysis of Supersonic Intake Buzz in an Axisymmetric Ramjet Engine

  • Yeom, Hyo-Won;Sung, Hong-Gye;Yang, Vigor
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.2
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    • pp.165-176
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    • 2015
  • A numerical analysis was conducted to investigate the inlet buzz and combustion oscillation in an axisymmetric ramjet engine with wedge-type flame holders. The physical model of concern includes the entire engine flow path, extending from the leading edge of the inlet center-body through the exhaust nozzle. The theoretical formulation is based on the Farve-averaged conservation equations of mass, momentum, energy, and species concentration, and accommodates finite-rate chemical kinetics and variable thermo-physical properties. Turbulence closure is achieved using a combined scheme comprising of a low-Reynolds number k-${\varepsilon}$ two-equation model and Sarkar's compressible turbulence model. Detailed flow phenomena such as inlet flow aerodynamics, flame evolution, and acoustic excitation as well as their interactions, are investigated. Mechanisms responsible for driving the inlet buzz are identified and quantified for the engine operating at subcritical conditions.

Fundamental Experiment of Underwater Ram-jet by PIV Measurement (PIV에 의한 수중램제트의 기초실험)

  • 김춘식
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2000.05a
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    • pp.165-170
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    • 2000
  • A fundamental experimental study for a substitute proposal to super-speed craft propulsion system called underwater ram-jet propulsion by high pressure air ejection as driving force was investigated. for basic study of effect of ram-jet propulsion performances ismple underwater ram-jet flow field was established and PIV(Particle Image Velocimetry) method was adopted to analyse the jet-induced flow appearing at ram intake mixing chamber and nozzle. Some flow dynamics relating to the high-speed ejector effect were discussed for the basic understanding for the ram-jet propulsion principle.

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