 | Negri M. Breakup behavior of non-Newtonian fluids with threads and droplets formation in impinging jet injectors / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Raumfahrtsysteme, Lampoldshausen. - Köln: DLR, 2014. - xxi, 142 p.: ill. - (Forschungsbericht; 2014-04). - Bibliogr.: p.136-141. - 75 р. - Пер. загл: Разрушительное действие неньютоновских жидкостей при формировании потока и капель, попадающих в струйный инжектор. - ISSN 1434-8454
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List of Figures ................................................ VI
List of Tables ................................................. XI
Nomenclature ................................................. XIII
Kurzfassung .................................................. XVII
Abstract ...................................................... XIX
Ringraziamenti & Acknowledgments .............................. XXI
Chapter 1. Introduction ......................................... 1
1.1 Research motivation: thread formation ...................... 1
1.2 State of the art of research on thread formation with
impinging jet injectors .................................... 2
1.3 Objectives ................................................. 5
1.4 Outline .................................................... 6
Chapter 2. Theoretical background ............................... 7
2.1 Elongational flow .......................................... 7
2.2 Basics of polymer solution chemistry ...................... 14
2.3 Deborah number ............................................ 76
2.4 Molecular theory for polymer solutions .................... 19
2.5 A note on compressibility ................................. 24
2.6 Breakup mechanism of a liquid sheet created by a doublet
impinging jet injector .................................... 27
Chapter 3. State of the art .................................... 35
3.1 Thread formation and droplet suppression .................. 35
3.2 Elongational rheometers ................................... 43
Chapter 4. Materials and methods ............................... 49
4.1 Spray test: experimental setup ............................ 49
4.2 Fluid characterization .................................... 51
4.3 Test fluids selection ..................................... 51
4.4 Preparation of the test fluids ............................ 53
4.5 Analysis of the systematic uncertainty .................... 54
Chapter 5. Capillary rheometer ................................ 59
5.1 Theoretical background .................................... 59
5.2 Experimental results ...................................... 67
5.3 Discussion ................................................ 73
Chapter 6. A Qualitative study of thread formation ............ 75
6.1 Shadowgraph images ........................................ 75
6.2 Properties influencing thread formation ................... 83
6.3 Discussion ................................................ 92
Chapter 7. Characterization of the spray behavior of Boger
fluids ......................................................... 95
7.1 Boger fluids: selection and characterization .............. 95
7.2 Spray behavior of the Boger fluids tested ................. 99
7.3 A quantitative analysis of thread formation in Boger
fluids ................................................... 107
7.4 Results and discussion ................................... 112
Chapter 8. Physical mechanisms leading to droplet or thread
formation ..................................................... 119
8.1 Phenomenology of droplet and thread formation ............ 119
8.2 Effects of elasticity on the breakup mechanism ........... 121
8.3 Influence of viscoelasticity on capillary instability .... 124
8.4 Conclusions .............................................. 127
Chapter 9. Conclusions ....................................... 129
9.1 Overview of the work conducted ........................... 129
9.2 Results obtained ......................................... 130
9.3 Application to gelled propellants ........................ 133
9.4 Outlook and recommendation for future works .............. 133
References .................................................... 136
Curriculum Vitae .............................................. 142
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