Effect of Injection Pressure on Nozzle Internal Flow and Jet Breakup under Sub-Cooled and Flash Boiling Test Conditions

2019 ◽  
Author(s):  
Shangze Yang ◽  
Xuesong Li ◽  
David L.S. Hung ◽  
Min Xu
Keyword(s):  
Injection Pressure ◽  
Internal Flow ◽  
Test Conditions ◽  
Jet Breakup ◽  
Flash Boiling

Characteristics and correlation of nozzle internal flow and jet breakup under flash boiling conditions

2018 ◽  
Vol 127 ◽  
pp. 959-969 ◽  
Author(s):  
Shangze Yang ◽  
Xuesong Li ◽  
David L.S. Hung ◽  
Min Xu
Keyword(s):  
Internal Flow ◽  
Jet Breakup ◽  
Flash Boiling

INTERNAL FLOW PATTERN AND MACROSCOPIC CHARACTERISTICS OF A FLASH-BOILING SPRAY ACTUATED THROUGH A TWIN-ORIFICE ATOMIZER WITH LOW INJECTION PRESSURE

2016 ◽  
Vol 26 (4) ◽  
pp. 377-410 ◽  
Author(s):  
Dehao Ju ◽  
Chunhai Wang ◽  
Xinqi Qiao ◽  
Jin Xiao ◽  
Zhen Huang
Keyword(s):  
Flow Pattern ◽  
Injection Pressure ◽  
Internal Flow ◽  
Flash Boiling

Visual Observation of Fragmentation Behavior on Molten Material Jet Surface in Coolant

2008 ◽  
Author(s):  
Yuta Uchiyama ◽  
Yutaka Abe ◽  
Akiko Fujiwara ◽  
Hideki Nariai ◽  
Eiji Matsuo ◽  
...  
Keyword(s):  
Water Surface ◽  
High Speed ◽  
Internal Flow ◽  
Core Material ◽  
Generation Process ◽  
High Speed Camera ◽  
Sodium Coolant ◽  
Molten Material ◽  
Fragmentation Behavior ◽  
Jet Breakup

For the safety design of the Fast Breeder Reactor (FBR), it is strongly required that the post accident heat removal (PAHR) is achieved after a postulated core disruptive accident (CDA). In the PAHR, it is important that the molten core material is solidified in sodium coolant which has high boiling point. Thus it is necessary to estimate the jet breakup length which is the distance that the molten core material is solidified in sodium coolant. In the previous studies (Abe et al., 2006), it is observed that the jet is broken up with fragmenting in water coolant by using simulated core material. It is pointed out that the jet breakup behavior is significantly influenced by the fragmentation behavior on the molten material jet surface in the coolant. However, the relation between the jet breakup behavior and fragmentation on the jet surface during a CDA for a FBR is not elucidated in detail yet. The objective of the present study is to elucidate the influence of the internal flow in the jet and fragmentation behavior on the jet breakup behavior. The Fluorinert™ (FC-3283) which is heavier than water and is transparent fluid is used as the simulant material of the core material. It is injected into the water as the coolant. The jet breakup behavior of the Fluorinert™ is observed by high speed camera to obtain the fragmentation behavior on the molten material jet surface in coolant in detail. To be cleared the effect of the internal flow of jet and the surrounding flow structure on the fragmentation behavior, the velocity distribution of internal flow of the jet is measured by PIV (Particle Image Velocimetry) technique with high speed camera. From the obtained images, unstable interfacial wave is confirmed at upstream of the jet surface, and the wave grows along the jet-water surface in the flow direction. The fragments are torn apart at the end of developed wave. By using PIV analysis, the velocity at the center of the jet is fast and it suddenly decreases near the jet surface. This means that the shear force acts on the jet and water surface. From the results of experiment, the correlation between the interfacial behavior of the jet and the generation process of fragments are discussed. In addition, the influence of surface instability of the jet induced by the relative velocity between Fluorinert™ and coolant water on the breakup behavior is also discussed.

Experimental Study of Spray Penetration under High Pressure Common Rail Condition

2011 ◽  
Vol 347-353 ◽  
pp. 66-69
Author(s):  
Jian Xin Liu ◽  
Song Liu ◽  
Hui Yong Du ◽  
Zhan Cheng Wang ◽  
Bin Xu
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Injection Pressure ◽  
Electronic System ◽  
Common Rail ◽  
Spray Penetration ◽  
Jet Breakup ◽  
Secondary Breakup ◽  
Breakup Time ◽  
High Pressure Common Rail

The fuel spray images were taken with an equipment (camera-flash-injection) which has been synchronized with a purpose made electronic system under the condition of the high pressure common rail in two injection pressure has been expressed in this paper. It is discovered when fitting spray tip penetration that after jet breakup for a period of time, the spray tip begin to slow down rapidly, and the speed of spray tip running becomes smooth. Hiroyasu and other traditional tip penetration fitting formula are fitting larger to this phase. This is because that after jet breakup, the secondary breakup of striker particles will occur under the influence of the aerodynamic, surface tension and viscosity force. Therefore, a spray penetration fitting formula containing secondary breakup time to fit penetration in three sections was proposed in this paper. Results show that when pressure difference increase, both first and second breakup time become earlier. The former is because of gas-liquid relative velocity increasing, while the latter is due to high speed interface movement acceleration increasing.

Macroscopic characteristics and internal flow pattern of dimethyl ether flash-boiling spray discharged through a vertical twin-orifice injector

Energy ◽  
2016 ◽  
Vol 114 ◽  
pp. 1240-1250 ◽  
Author(s):  
Dehao Ju ◽  
Zhong Huang ◽  
Xiaoxu Jia ◽  
Xinqi Qiao ◽  
Jin Xiao ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Dimethyl Ether ◽  
Internal Flow ◽  
Flash Boiling

In-nozzle bubble formation and its effect on fuel jet breakup under cavitating and flash boiling conditions

2021 ◽  
Vol 183 ◽  
pp. 116120
Author(s):  
Shangze Yang ◽  
Shangning Wang ◽  
Zhe Sun ◽  
Xuesong Li ◽  
David L.S. Hung ◽  
...  
Keyword(s):  
Bubble Formation ◽  
Jet Breakup ◽  
Fuel Jet ◽  
Flash Boiling

Characterization of Flow Structures in a Diesel Injector for Different Needle Lifts and a Fluctuating Injection Pressure

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alexandre Pelletingeas ◽  
Louis Dufresne ◽  
Patrice Seers
Keyword(s):  
Steady State ◽  
Coherent Structures ◽  
Injection Pressure ◽  
Internal Flow ◽  
Orthogonal Decomposition ◽  
Navier Stokes ◽  
Flow Structures ◽  
Single Hole ◽  
Proper Orthogonal

This paper aims at analyzing the needle lift's influence on the internal flow of single-hole diesel injector to identify flow structures. A numerical Reynolds-Averaged Navier–Stokes (RANS) model of a single-hole diesel injector was developed and validated to study the flow's dynamic for different needle's lifts and subjected to realistic injection pressure. The main findings are: (1) under steady injection pressure, flow coefficients reached a steady-state value and maximum injected fuel mass flow rate is reached at intermediate needle's lifts. (2) The sac volume is the area with several vortex structures due to the throttling between the needle body and the injector body. (3) The frequency of the fluctuating injection pressure can excite the initial jet entering the sac volume similarly to the Coanda effect. Finally, using a proper orthogonal decomposition (POD) allowed extracting coherent structures within the sac volume and putting in evidence a reorganization of the flow.

Numerical Simulation of Internal Flow and Spray of Liquid Phase LPG (Liquefied Petroleum Gas) Injection

2008 ◽  
Author(s):  
Boyan Xu ◽  
Yunliang Qi ◽  
Shaoli Cai ◽  
Deqiang Geng
Keyword(s):  
Numerical Simulation ◽  
Liquid Phase ◽  
Initial Conditions ◽  
Gas Injection ◽  
Injection Pressure ◽  
Internal Flow ◽  
Liquefied Petroleum Gas ◽  
Sauter Mean Diameter ◽  
Mean Diameter ◽  
Nozzle Geometries

Cavitation and flashing formed inside and outside of an injector, respectively, have significant effect on liquid phase LPG (Liquefied Petroleum Gas) injection. Numerical simulations of internal flow of the liquid phase LPG inside different injector nozzles were performed using the FIRE CFD code. The results showed that the cavitation always occurred at the inlet corner of the nozzle with negative pressure and higher velocity regardless the nozzle geometries. The relationships between vapor void fraction at the exit of the nozzle and injection pressure were also investigated for different nozzle geometries. The spray of the liquid phase LPG was further simulated by using the results of the internal flow as initial conditions. During the simulation of the spray, the effect of superheat degree on evaporation was considered and a modified evaporation equation was employed. The comparison of the simulation with experimental results showed that, with the injection pressure increasing, spray tip penetration increased but SMD (Sauter mean diameter) decreased.

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