The Influence of Actual Layout and Off-Axis Needle Stroke on Diesel Nozzle Flow Under Ballistic Needle Displacement

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Fulvio Palmieri
Keyword(s):  
Injection Pressure ◽  
Operating Conditions ◽  
Dynamics Modeling ◽  
Split Injection ◽  
Computational Fluid Dynamics Modeling ◽  
Fuel Flow ◽  
High Injection Pressure ◽  
Flow Features ◽  
Diesel Nozzle

The injection of small amount of diesel fuel relies on the shortening of energizing signal. In such injection conditions, the needle does not reach the mechanical stroke-end and its displacement is defined as ballistic. Some specific experimental work has been performed on how the dynamics of injector needle is reflected on the fuel flow pattern within the nozzle. Due to the intrinsic difficulties of the field, just single axial hole injectors have been optically investigated in real time, by means of the most advanced X-ray techniques. In the current study, based on 3D-computational fluid dynamics modeling, the investigation has been extended to multihole injector layouts, under typical pilot/split injection conditions, namely, high injection pressure and low needle lift. The role of different factors on the flow development within the nozzle has been shown and discussed; the investigations have taken into account actual injector tip layouts and the response to the needle off-axis operating conditions. Results are presented highlighting the flow features within the nozzle and their reflects on the hole-to-hole differences.

Actual Tip Layout and Off-Axis Stroke in Nozzle Flow Modeling Under Ballistic Needle Displacement

2012 ◽  
Author(s):  
Giancarlo Chiatti ◽  
Fulvio Palmieri
Keyword(s):  
Injection Pressure ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Nozzle Flow ◽  
Flow Modeling ◽  
Split Injection ◽  
Fuel Flow ◽  
High Injection ◽  
High Injection Pressure

The injection of small amount of diesel fuel is mainly achieved through the shortening of energizing signal. Consequently, in such injection phases, the needle does not reach the mechanical stroke-end and its displacement may be defined as ballistic. By means of a detailed 3D-CFD modeling, the behavior of nozzle flow is investigated under typical pilot/split injection conditions, namely high injection pressure and low needle lift. The investigation focuses on the effects of the restricted flow passage on fuel flow at hole inlets. Once the modeling details are described, the influence of different elements on the internal fuel flow is shown and discussed, pointing out the role of different driving factors; investigations take into account actual injector tip layouts and the response to the needle off-axis operating conditions. Results are presented highlighting the flow pattern features within the nozzle and their reflects on the hole-to-hole differences.

Study on Influence of Nozzle Structure on Flow in Diesel Nozzle Orifice

2012 ◽  
Vol 246-247 ◽  
pp. 127-130
Author(s):  
Bing Li ◽  
Xue Song Hu ◽  
Xiao Feng Cao ◽  
Gui Qi Jia ◽  
Fang Xi Xie ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Key Factors ◽  
Complex Flow ◽  
Two Phase ◽  
Nozzle Orifice ◽  
Fuel Flow ◽  
Flow Features ◽  
Diesel Nozzle ◽  
Nozzle Hole

The fuel flow characteristics in diesel nozzle orifice are key factors to the atomization of fuel near the nozzle orifice. In the paper, two-phase flow model is used to simulate the complex flow features in nozzle orifice, and to study the influences of the relative position of nozzles orifice axis and nozzle axis, and inclination angle of nozzle hole on the internal flow feature.

Computational Fluid Dynamics Modeling of Oxy-Fuel Flames: The Role of Soot and Gas Radiation

2012 ◽  
Vol 26 (5) ◽  
pp. 2786-2797 ◽  
Author(s):  
Stefan Hjärtstam ◽  
Robert Johansson ◽  
Klas Andersson ◽  
Filip Johnsson
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
Gas Radiation

Visualization of diesel spray and combustion from lateral side of two-dimensional piston cavity in rapid compression and expansion machine, second report: Effects of injection pressure and interval of split injection

2021 ◽  
pp. 146808742199306
Author(s):  
Chengyuan Fan ◽  
Keiya Nishida ◽  
Yoichi Ogata
Keyword(s):  
Combustion Process ◽  
Injection Pressure ◽  
Lateral Side ◽  
Two Dimensional ◽  
Split Injection ◽  
High Injection ◽  
High Injection Pressure ◽  
Compression And Expansion ◽  
Combustion Processes ◽  
Injection Pressures

The effect of split injection on the fuel spray and combustion processes in a rapid compression and expansion machine was investigated using the visualization process. A two-dimensional piston cavity, designed with the cross section of a reentrant piston, was installed in the combustion chamber to observe the combustion process from the lateral side. Combustion experiments were conducted with injection pressures of 80 MPa, 120 MPa, and 180 MPa and an O2 concentration of 15%. The spray/wall interaction, mixture distribution, and ignition location were investigated using the shadow method. Along with natural flame luminescence, different spray impinging behaviors on combustion process were studied. Furthermore, the combustion characteristics of in-cylinder pressure, apparent heat release rate, and combustion phase were recorded and analyzed simultaneously. The results showed that both high injection pressure and split injection with a longer interval effectively improved the combustion performance. In addition, when the pilot injection was advanced further, the injection interval had a larger influence in reducing soot generation, while the effect of high injection pressure on heat release decreased. Flame separation was found to occur at high injection pressures. It was observed that the flame separation caused by the strong spray momentum was beneficial for reducing soot generation owing to the greater fuel-air interaction area. The spray and combustion processes were investigated in detail, and the significant effects of different injection pressures and injection intervals on combustion performance with the split injection method were highlighted.

Experimental and computational fluid dynamics modeling of a novel tray humidifier column in humidification dehumidification desalination; evaluation of hydrodynamic and heat transfer characteristics

2020 ◽  
Vol 234 (3) ◽  
pp. 275-284
Author(s):  
Taleb Zarei ◽  
Reza Hamidi Jahromi ◽  
Arash Mohammadi Karachi
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Rectangular Cross Section ◽  
Seawater Temperature ◽  
Operating Conditions ◽  
Dynamics Modeling ◽  
Heat Transfer Characteristics ◽  
Computational Fluid Dynamics Modeling ◽  
Transfer Characteristics

In this article, a novel tray humidifier column for humidification dehumidification desalination was proposed. The performance of the humidifier column has been investigated with experimental and computational fluid dynamics simulations. The hydrodynamics and heat transfer characteristics of this tray humidifier has been studied. A stainless steel sieve tray with a rectangular cross section with a dimension of 20 × 50 cm was used in the experimental study. In computational fluid dynamics modeling, a transient three-dimensional model has been developed based on the volume of fluid framework by using standard k-epsilon model. The effect of air and seawater flow rate and inlet seawater temperature on the exit air temperature has been investigated. The results show that the humidifier effectiveness of the tray humidifier column varies between 0.67 and 0.87 depending on operating conditions. Then, tray column can be used in humidification dehumidification desalination systems with advantages such as compact equipment, low-pressure drop, and handling solids or other sources of fouling.

scholarly journals Optical experiments of string cavitation in diesel injector tapered nozzles

2020 ◽  
Vol 24 (1 Part A) ◽  
pp. 193-201 ◽  
Author(s):  
Genmiao Guo ◽  
Zhixia He ◽  
Xicheng Tao ◽  
Shenxin Sun ◽  
Zhen Zhou ◽  
...  
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Typical Development ◽  
Type B ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Fuel Flow ◽  
Diesel Nozzle ◽  
Development Processes ◽  
Occurrence Regularity

Flow inside the diesel nozzle is crucial to spray, combustion, and emissions. This work aimed to improve the understanding of effects of internal fuel-flow on diesel spray, especially the special string cavitating flow. Optical experiments were employed for characterizing the formation of string cavitation inside the transparent scaled-up tapered diesel orifices. Simultaneously, the corresponding evolution of spray cone angles were obtained. Results show that there were two origins of the string cavitation, which were originated from inlet and outlet of the orifice, respectively. Moreover, there were two typical development processes of the string cavitation between hole and hole, which were defined as type-A and type-B string cavitation. Furthermore, effects of string cavitation were analyzed: it could trigger the geometry-induced cavitation and make a sharp increase of spray cone angle. Finally, the relationships between the occurrence regularity of string cavitation, the needle lift and the injection pressure were revealed by comparison of different needle lifts and different injection pressures.

scholarly journals Experimental investigation on lubricity of 2,5-dimethylfuran blends

2012 ◽  
Vol 148 (1) ◽  
pp. 2-10
Author(s):  
Farshad ESLAMI ◽  
Miroslaw WYSZYNSKI ◽  
Athanasios TSOLASKIS ◽  
Hongming XU ◽  
Shahrouz NOROUZI ◽  
...  
Keyword(s):  
Alternative Fuels ◽  
Direct Injection ◽  
Injection Pressure ◽  
Spark Ignition Engines ◽  
Test Rig ◽  
High Injection ◽  
High Injection Pressure ◽  
Ethanol Blends ◽  
Fuel Lubricity

Spark ignition engines fuelled with alternative fuels are the topic of many studies. As alternatives for gasoline, ethanol and recently 2,5-dimethylfuran (DMF) have been investigated for their different properties. Lubricity analysis of fuels in fuel systems is vital because of the lubricating role of fuel. Lubricity of gasoline and its alternatives became important since introduction of direct-injection gasoline fuel pump with high injection pressure becoming closer to diesel pumps. Therefore, this work examines the lubricity properties of gasoline and its blends with alternative fuels using a HFRR lubricity test rig. Results showed that DMF as an additive to gasoline improved the lubricity of blend; this effect was increasing with the percentage of DMF. These results can be compared with DMF-ethanol blends which displayed the same pattern but with lower enhancing role of DMF. The DMF fuel was kept in storage for seven months and then the same experiments were repeated (DMF Ageing). Smaller wear scar and better lubricity effects were achieved by using the aged DMF. These results highlight the potential of DMF to become an additive for gasoline and its alternatives.

Role of Reynolds and Archimedes numbers in particle-fluid flows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Haim Kalman
Keyword(s):  
Flow Regime ◽  
Power Function ◽  
Fluid Flows ◽  
Limited Range ◽  
Operating Conditions ◽  
Pneumatic Conveying ◽  
Particulate Materials ◽  
Simple Power ◽  
Simple Power Function

AbstractAny scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

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