듀얼 매니폴드 가변추력 인젝터 특성에 대한 실험적 연구

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2011.2. 윤영빈.Maste

분말 연료를 이용한 입자 부상 분사기의 분무특성

학위논문 (박사)-- 서울대학교 대학원 : 계항공공학부, 2016. 2. 윤영빈.Spray characteristics of particle-laden injector were experimentally investigated for the particle (aluminum, magnesium) as a fuel. Spray characteristics of gas centered gas-liquid shear coaxial injector were investigated varying injection condition under seawater injected as a liquid phase. Similarity characteristics of particle and carrier gas were investigated in particle-laden jet, and mixing characteristics between particle and coaxial gas also investigated using shear and swirl coaxial injector. Mass flow rate and direct photograph were used to investigte the spray characteristics such as breakup process of liquid sheet in gas centered gas-liquid shear coaxial injector. Self-pulsation occurs in that injector and it is accompanied by an intensive noise. Self-pulsation generate the pressure and flow rate oscillation in gas and liquid phase. Because of this oscillation can argument combustion instabilities, self-pulsation should be suppressed. Effect of recess and Reynolds number of liquid and gas phase on self-pulsation characteristics were studied by measured frequency of liquid sheet under self-pulsating condition. It was found that the different self-pulsation occurred by the recess number of injector. Self-pulsation occurred by the liquid bubble collapse process under low recess case, however liquid sheet and central gas interaction in nozzle inside dominate the oscillation of liquid sheet. Small particle of 1μm represent a fluid characteristics and large particle with 42.5 mean diameter used as a fuel were simultaneously injected for investigate effect of particle on a carrier gas and particle characteristics in particle-laden jet. Particle mass loading ratio effects on a velocity and turbulence intensity of carrier gas, and carrier gas and particle can agreed with similarity. Effect of particle mass loading ratio on carrier gas in jet developing region differs from fully developed region. Accordingly, centerline velocity decay of carrier gas were formulated in jet developing region and fully developed region, respectively, and were compared with the previous results. Centerline velocity decay of particle were formulated with particle Reynolds number, because particle drag force determined by the particle Reynolds number. Previously study, change in turbulence intensity can determined by the ratio of particle diameter and turbulence length scale. The present experimental data suggests that, consideration of the characteristic length scales (particle diameter and turbulence length scale) is insufficient to predict gas-phase turbulence modulation in particle-laden flow, because as slip velocity between gas and particle increases turbulence intensity also increased. Therefore, slip velocity also considered to predict gas-phase turbulence modulation. In addition, Mie scattering and acetone PLIF technique were used for particle and coaxial gas, respectively, to investigate mixing characteristics between particle and coaxial gas. Mixing efficiency of shear coaxial was higher than swirl coaxial under injector without recess, and mixing efficiency was sensitive to the change of velocity ratio between coaxial and central jet. As for the swirl coaxial injector with recess, mixing efficiency was higher than shear coaxial and less sensitive the change of velocity ratio, so swirl coaxial injector can be used for solid particle propulsion system with large operating range.CHAPTER1 1 INTRODUCTION 1 CHAPTER 2 EXPERIMENT AND MEASUREMENT SYSTEMS 6 2.1 Automated Particle Feeder 6 2.2 Two-phase Jet Measurement Technique 8 2.2.1 Phase Discrimination Using Image Processing 8 2.2.2 Validation of the Image Processing Technique 17 2.3 Simultaneous PIV and Acetone PLIF Diagnostics 20 2.3.1 Particle Image Velocimetry 20 2.3.2 Acetone PLIF 24 2.3.3 Simultaneous Measurement System 30 CHAPTER 3 SPRAY CHARACTERISTICS OF GAS/LIQUIG SHEAR COAXIAL INJECTOR WITH ANNULAR LIQUID SHEETS 32 3.1 Background and Objectives 32 3.2 Experimental Apparatus and Methods 34 3.3 Self-pulsation Characteristics 38 3.3.1 Spray Patterns 38 3.3.2 Low Recess Ratio (RR1.67) 42 3.3.3 High recess ratio (RR=3.34) 46 CHAPTER 4 SPRAY CHARACTERISTICS OF CARRIER GAS AND PARTICLES IN PARTICLE-LADEN SIMPLE JETS 50 4.1 Background and Objectives 50 4.2 Experimental Conditions 52 4.3 Fluidic Characteristics of Particle and Carrier Gas 56 4.3.1 Mean Velocity Characteristics 56 4.3.2 Similarity Characteristics of Particle and Carrier Gas 61 4.3.3 Similarity of Particle Number Density 66 4.4 Scaling of the Centerline Velocity Decay 69 4.4.1 Centerline Velocity Decay of Gas Phase 69 4.4.2 Centerline Velocity Decay of Particle 74 4.5 Turbulence Modulation 77 CHAPTER 5 SPRAY CHARACTERISTICS OF PARTICLE-LADEN COAXIAL JETS 85 5.1 Background and Objectives 85 5.2 Experimental Conditions 88 5.3 Effect of Particle Loading Ratio on Gas Phase Velocity 92 5.4 Particle Distribution Characteristics 95 5.5 Mixing Characteristics 100 5.5.1 Fuel and Oxidizer Distributions 100 5.5.2 Mixing Process 103 5.5.3 Mixing Efficiency 107 5.5.4 Recess ratio effects on mixing efficiency 111 CHAPTER 6 CONCLUSION 115 REFERENCES 118 ABSTRACT IN KOREAN 125Docto