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A Study on Dynamic Characteristics of Gas Centered Swirl Coaxial Injector with Liquid Excitation

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dc.description학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 윤영빈.-
dc.description.abstractIt is important to study on the combustion instability to develop liquid rocket engines for preventing lower combustion efficiency and destruction of the combustion chamber. Various methods such as a baffle and cavity are used to prevent the combustion instability. It is important to suppress the combustion instability by designing an injector because it is in the middle of the process of the disturbance propagating in a rocket engine. Most of studies on the injector focuses on the simplex injector with liquid pulsation. In real rocket engine system, however, coaxial injectors are primarily used. In previous studies on a gas-centered swirl-coaxial injector, the dynamics characteristics and the spray pattern was analyzed on the condition of gas excitation. Therefore, research on coaxial injector with liquid pulsation is essential. In this study, instability of liquid fuel flow with perturbation of liquid propellant flow in a gas-cantered swirl- coaxial injector was investigated using air and water. The liquid perturbation was generated by a mechanical pulsator, and film thickness variation at the end of the injector which affects spray characteristics such as spray angle, break up length, and Sauter mean diameter(SMD) was measured using electrodes. The spray image which shows the evidence of the flow fluctuation such as a monolayer and spray width changes was achieved using DSLR camera and high speed camera. The dynamic characteristics of the gas-centered swirl-coaxial injector was studied varying tangential inlet diameter and gap thickness without gas flow. In addition, the response characteristics of the injector was investigated varying the momentum flux ratio while the gas and liquid were simultaneously injected.-
dc.description.tableofcontentsChapter 1 INTRODUCTION 1

1.1 Combustion instability 1
1.2 Overview of previous research 4
1.3 Objectives 6


2.1 Experimental apparatus and method 7
2.2 Experimental condition 11

Chapter 3 Result and Discussion 13

3.1 Definition of gain 13
3.2 Tangential inlet diameter 15
3.3 Gap thickness 32
3.3.1 Magnitude of gain 33
3.3.2 Sharp drop 36
3.4 Existence of gas flow 38

Chapter 4 CONCLUSION 42

Bibliography 44

Abstract in Korean 46
dc.format.extent1930556 bytes-
dc.publisher서울대학교 대학원-
dc.subjectliquid rocket engine-
dc.subjectgas centered swirl coaxial injector-
dc.subjectdynamic characteristics-
dc.subjectliquid excitation-
dc.titleA Study on Dynamic Characteristics of Gas Centered Swirl Coaxial Injector with Liquid Excitation-
dc.citation.pagesx, 47-
dc.contributor.affiliation공과대학 기계항공공학부-
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