Internal Flow and Atomization Characteristics of Intersecting Hole Nozzles
Xiaorong Wang
Jiangsu University of Science and Technology
Copyright © 2019 by Cayley Nielson Press, Inc.
ISBN: 978-1-5323-9661-8
Cayley Nielson Press Scholarly Monograph Series Book Code No.: 209-4-1
US$146.50
Preface
Since the invention of the self-compressed ignition engine, the diesel engine has continuously integrated advanced technologies such as turbocharger, four-valve technology, EGR technology and high-pressure jet technology, and has become one of the most thermally efficient engines. At present, the diesel fuel injection system has evolved from the original mechanical fuel injection system to the most promising high-pressure common rail injection system, with the aim of increasing the area of evaporation and gasification to increase the combustion rate and reduce emissions. The formation of atomization directly affects the quality of the mixture in the fuel atomization cylinder, thereby affecting engine power, economy and emissions.
Favorable fuel atomization combustion is very important to improve the diesel engine power and release emissions. The existing research has shown that the fuel atomization characteristics of internal combustion engine are affected by the hole and turbulence in the nozzle hole. The greater the turbulence intensity near the outlet of the nozzle, the better the atomization effect, which can significantly affect the droplet size, spray cone angle and penetration distance. The morphology, geometry and distribution of the nozzle orifice have a certain influence on the cavity and turbulence disturbance in the nozzle, which in turn affects the atomization characteristics of the fuel.
In order to obtain better combustion effect, many scholars have carried out a lot of exploration on the factors affecting the injection pressure, the movement of the airflow in the cylinder, and the structure of the nozzle. The research on nozzles indicates that the geometry of the nozzle shape affects the evolution of in the nozzle multiphase flow, and affects the spray and combustion process. Therefore, improving the nozzle geometry is also an important way to improve the spray and combustion characteristics. The inner/outer cross-hole nozzles exhibit a good atomization effect in the spray atomization test, which is beneficial to improve the combustion of the diesel engine cylinder and realize the in-machine purification of pollutants, and has the value of further exploration.
Chapters 2-5 of this book introduce the study of internal flow and fuel atomization characteristics of coupled cross-nozzles, and study the influence of self-injection angle, injection pressure and combustion chamber pressure on the internal flow characteristics of cross-nozzle. On this basis, the combustion atomization characteristics of the cross-nozzle under the coupling nozzle are studied, including the angle of the sub-nozzle, the injection pressure and the influence of the combustion chamber pressure on the atomization characteristics. The flow characteristics of the two-phase flow in the cross-nozzle under steady state and transient state are studied in Chapters 6-7 of this book. The effects of length-diameter ratio, cross-angle and sub-nozzle shrinkage coefficient on internal flow characteristics are studied in detail. On this basis, the effects of pressure fluctuation replication, frequency and nozzle geometry on the internal flow characteristics of the intersecting orifice are studied.
This book was written by Professor Xiaorong Wang. At the same time, thanks to Genzhu Jiang and Wenxian Tang for reviewing this book. In addition, Jinxin Zhang, Haitao Huang, Jigang Wang, Minglu Dai, Yulong Xie, Jiaxing Chen, Yin Ma, Huili Luo, Jun Yan, Gang Wang, Ning Wei, Jie Zhang Yang Yu and Tong Li have contributed to this book.
Xiaorong Wang
School of Mechanical and Technology
Jiangsu University of Science and Technology
Jiangsu, China
May, 2019
Contents
Preface........................................................................................... I
1 Introduction....................................................................................... 1
1.1 The background and significance of the research..................... 1
1.2 The current situation of research at domestic and abroad........ 3
1.2.1 Research status of fuel injector structure................................ 3
1.2.2 Research status of fuel atomization......................................... 8
1.3 The main research content of this paper................................... 16
2 Fuel atomization model coupled with internal flow.................. 18
2.1 Mathematical model of internal flow....................................... 18
2.1.1 Basic governing equation........................................................ 18
2.1.2 Turbulence model.................................................................... 22
2.1.3 Cavity model............................................................................ 25
2.2 Mathematical model of fuel atomization................................. 29
2.2.1 Evaporation model................................................................... 29
2.2.2 Fragmentation model............................................................... 31
2.2.3 Turbulent diffusion model...................................................... 34
2.2.4 Impinging mode....................................................................... 35
2.3 Establishment of a fuel atomization model coupled with internal flow 36
2.4 Chapter summary........................................................................ 38
3 Simulation and verification of cross-nozzle fuel atomization coupled with internal flow 39
3.1 Geometric model and mesh generation of cross nozzle......... 39
3.2 Boundary conditions and initial conditions of intersecting orifices 43
3.3 Internal flow simulation and experimental verification of cross-nozzle 44
3.4 Simulation and experimental verification of cross-nozzle fuel atomization in coupled internal flow...... 45
3.5 Chapter summary........................................................................ 46
4 Analysis of internal flow characteristics of cross-nozzles......... 47
4.1 Effect of sub-nozzle angle on flow characteristics in cross-nozzle 47
4.2 Effect of injection pressure on internal flow characteristics of intersecting orifices 54
4.3 Effect of combustion chamber pressure on internal flow characteristics of crossed nozzles 59
4.4 Comparative analysis of internal flow characteristics of single and intersecting orifices 63
4.4 Chapter summary........................................................................ 69
5 Analysis of the atomization characteristics of the cross-nozzle in the coupled internal flow 72
5.1 Effect of the angle of sub-nozzle on atomization characteristics 72
5.1.1 Influence law on penetration and SMD................................ 73
5.1.2 Influence law on the cone angle of fan spray....................... 75
5.1.3 Influence law on the characteristics of spray space............. 77
5.1.4 Influence law on the quality of mixed air............................. 79
5.2 Effect of injection pressure on atomization characteristics... 80
5.2.1 Influence law on penetration and SMD................................ 81
5.2.1 Influence law on the cone angle of fan spray....................... 83
5.2.3 Influence law on the characteristics of spray space............. 84
5.2.4 The Law of Influencing Mixed Air Quality.......................... 86
5.3 Effect of Combustion Chamber Pressure on Atomization Characteristics 87
5.3.1 Influence law on penetration and SMD................................ 87
5.3.2 Influence law on the cone angle of fan spray....................... 89
5.3.3 Influence law on the characteristics of spray space............. 90
5.3.4 Influence law on the quality of mixed air............................. 93
5.4 Comparative analysis of atomization characteristics of single hole and crossed hole 94
5.4.1 Comparative analysis of penetration and SMD................... 94
5.4.2 Comparative analysis of spray cone angle............................ 96
5.4.3 Comparative analysis of spray space characteristics........... 97
5.4.4 Comparative analysis of blended air quality........................ 98
5.5 Chapter summary........................................................................ 99
6 Gas-liquid two-phase flow characteristics in cross-nozzle under steady state 101
6.1 Effect of length to diameter ratio on internal flow characteristics 101
6.1.1 Effect on pressure distribution and hole distribution inside the nozzle 102
6.1.2 Effect on mass flow at nozzle outlet................................... 104
6.1.3 Effect on the velocity at the nozzle exit.............................. 108
6.1.4 Effect on the turbulent kinetic energy at the nozzle exit... 112
6.2 Influence of intersection angle on internal flow characteristics 116
6.2.1 Effect on pressure distribution and hole distribution inside the nozzle 117
6.2.2 Effect on mass flow at nozzle outlet.................................... 118
6.2.3 Effect on the velocity at the nozzle exit.............................. 120
6.2.4 Effect on the turbulent kinetic energy at the nozzle exit.. 123
6.3 Effect of sub-nozzle shrinkage coefficient on internal flow characteristics 126
6.3.1 Effect on pressure distribution and hole distribution inside the nozzle 127
6.3.2 Effect on mass flow at nozzle outlet................................... 130
6.3.3 Effect on the velocity at the nozzle exit.............................. 133
6.3.4 Effect on the turbulent kinetic energy at the nozzle exit.. 137
6.4 Chapter summary...................................................................... 141
7 Gas-liquid two-phase flow characteristics in crossed nozzles under transient conditions 143
7.1 Effect of pressure fluctuation amplitude on internal flow characteristics of nozzle 144
7.2 Effect of pressure fluctuation frequency on internal flow characteristics of nozzle 149
7.3 Effect of nozzle geometry on internal flow characteristics. 154
7.3.1 Effect of aspect ratio on internal flow characteristics....... 155
7.3.2 Influence of cross angle on internal flow characteristics.. 161
7.3.3 Effect of sub-nozzle shrinkage coefficient on internal flow characteristics 167
7.4 Chapter summary...................................................................... 174
Readership
This book should be useful for students, scientists, engineers and professionals working in the areas of optoelectronic packaging, photonic devices, semiconductor technology, materials science, polymer science, electrical and electronics engineering. This book could be used for one semester course on adhesives for photonics packaging designed for both undergraduate and graduate engineering students.
