Experimental Study on Jet Breakup Morphologies and Jet Characteristic Parameters of Non-circular Nozzles under Low-intermediate Pressures

2019 ◽  
Vol 35 (4) ◽  
pp. 617-632
Author(s):  
Yue Jiang ◽  
Hong Li ◽  
Lin Hua ◽  
Daming Zhang ◽  
Zakaria Issaka
Keyword(s):  
Surface Wave ◽  
High Speed ◽  
Flow Behavior ◽  
Initial Section ◽  
Droplet Formation ◽  
High Speed Photography ◽  
Breakup Length ◽  
Jet Breakup ◽  
Circular Jets ◽  
Pressure Water

Abstract. A High-Speed Photography (HSP) technique was used to investigate the breakup process and flow behavior of low-intermediate pressure water jets issued from square and triangular shaped nozzles. The non-circular orifices were designed based on the principle of equal flowrate with the same pressure in relation to the circular orifice. The breakup morphologies and boundary structures of the jets were studied under different nozzles and working pressures. Two forms of droplet formation and the process of droplet formation, in addition to the jet breakup lengths, initial amplitudes of surface waves and jet diffusion angles of different nozzles were evaluated. It was found that the jet presented a good continuity and fluidity in the initial section, and the fluid bands gradually appeared due to the air resistance and the jet break up as the disturbance intensifies. The degree of jet breakup was enhanced with the increase of pressure and cone nozzle angle. The random appearance of the fluid band structures and the dactylitic textures near the nozzles for non-circular jets appeared earlier than those produced by the circular jets. The small satellite droplets with different shapes and sizes were seen inside and outside the jet interface. Triangular jets exhibited the shortest breakup length, the initial amplitude of surface wave, and the diffusion angle of the jet at the same pressure were largest compared with square and circular jets. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular nozzles were fitted with a relative error of less than 10%, which means the fitting formulas are accurate. Keywords: Breakup length, High-speed photography, MATLAB simulation, Non-circular nozzle, Surface wave amplitude.

Hydraulic Performance and Jet Breakup Characteristics of the Impact Sprinkler with Circular and Non-circular Nozzles

2019 ◽  
Vol 35 (6) ◽  
pp. 911-924 ◽  
Author(s):  
Yue Jiang ◽  
Hong Li ◽  
Chao Chen ◽  
Lin Hua ◽  
Daming Zhang
Keyword(s):  
High Speed ◽  
Cone Angle ◽  
Hydraulic Performance ◽  
High Speed Photography ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Circular Jets ◽  
Square Jets ◽  
The Impact

HighlightsThe hydraulic performance of the impact sprinkler with circular and non-circular nozzles were measured.A High-Speed Photography (HSP) technique was employed to extract the jet breakup process of the impact sprinkler.Two index equations of jet characteristic lengths and equivalent diameters of non-circular nozzles were fitted. Abstract. An experiment was carried out to investigate the hydraulic performance of an impact sprinkler by using circular and non-circular nozzles. A High-Speed Photography (HSP) technique was employed to extract the breakup process and flow behavior of low-intermediate pressure water jets issued from the different types of orifices. These orifices were selected by the principle of equal flowrate with the same pressure. Moreover, two characteristic lengths: the jet breakup length and the initial amplitude of surface wave were measured. It was found that the sprinkler with circular nozzles produced the largest radius of throw followed by square nozzles and regular triangular nozzles when the cone angle of nozzle and pressure were unchanged, while the sprinkler with regular triangular nozzle had the best variation trend of water distribution and combination uniformity coefficient. Regular triangular jets exhibited a higher degree in breakup and the shortest breakup length compared with the square jets and the circular jets. The initial amplitudes of surface waves of regular triangular jets were larger than the square jets and the circular jets with the same cone angle. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular orifices were fitted with a relative error of less than 10%, which means the fitting formulas were accurate. Keywords: Breakup length, Fitting formula, Hydraulic performance, Initial amplitude, Non-circular jets.

Jet Breakup and Droplet Formation in Immiscible Liquid-Liquid System

2016 ◽  
Author(s):  
Shimpei Saito ◽  
Yuzuru Iwasawa ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Tetsuya Kanagawa ◽  
...  
Keyword(s):  
Weber Number ◽  
Droplet Diameter ◽  
Droplet Formation ◽  
Liquid System ◽  
Immiscible Liquid ◽  
Satellite Droplet ◽  
Breakup Length ◽  
Jet Breakup ◽  
Fundamental Process ◽  
Median Diameter

Mitigative measures against the event of a core disruptive accident (CDA) are of the importance from the viewpoint of safety of a sodium-cooled fast reactor (SFR). If the CDA occurs, the so-called post-accident heat removal must be surely achieved. The present study focuses on the scenario that the molten materials are injected into the lower plenum as jets. The jet breakup behavior during the CDA will be very complicated. Therefore, a specialized study on the fundamental process during the jet breakup is believed to be an effective approach. The aim of this paper is to understand the fundamental process of hydrodynamic interaction of jet breakup and droplet formation Using the immiscible liquid-liquid system, water and silicon oil as the test fluids, visualization via high-speed videography was performed. From the visualization results, the breakup length and droplet diameter were measured by image processing. The experimental data were scaled with ambient Weber number. When the Weber number was smaller than 1, the droplet diameter was close to the nozzle diameter, and distribution of droplet size was not observed. When the Weber number exceeded 1, the breakup length became longer and the generated droplet diameter possessed a distribution with two peaks due to satellite droplet formation. In both cases, the droplet formed at the leading edge of jet. In case that Weber number is around 100, the droplets were formed by entrainment of interfacial wave at jet side. From the mass median diameter data, we can see that the increase of the Weber number caused the decrease of median diameter and the increase of the width of the distribution.

Experimental Investigation of Liquid Jet Breakup in a Cross Flow of a Swirling Air Stream

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach number 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using matlab to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes—bag breakup, column breakup, shear breakup, and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15 deg swirl show reduced breakup length and penetration related to the nonuniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

The brittle fracture of solids by liquid impact, by solid impact, and by shock

1964 ◽  
Vol 282 (1390) ◽  
pp. 331-352 ◽  
Keyword(s):  
Surface Wave ◽  
High Velocity ◽  
High Speed ◽  
Turbine Blades ◽  
Explosive Loading ◽  
Back Surface ◽  
High Speed Photography ◽  
Liquid Mass ◽  
Liquid Impact ◽  
The Impact

The type of stress pulse produced when a liquid mass strikes a solid at high velocity is first examined. Compressible behaviour, giving rise to a sharp peak of pressure, is found to occur in the initial stages of the impact. The duration of this peak depends on the dimensions and impact velocity of the liquid mass, and also on the compressible wave velocity for the liquid. A comparison is made with pulses produced by solid/solid impact and by the detonation of small quantities of explosive. Both the high-speed liquid impact and the explosive loading give intense pulses of duration only a few microseconds. A solid/solid impact has, by comparison, a much longer impact time of the order of hundreds of microseconds. The fracture of glasses and hard polymers using these three types of loading is described. The development of fracture is followed by high-speed photography. Differences in the modes of fracture are attributed to variations in the shape and duration of the applied stress pulses. Short circumferential fractures produced around the loaded area in liquid impact and explosive loading are shown to be initiated by the Rayleigh surface wave at points where flaws existed. More complex fracture patterns on the front surfaces of plates are due to the reinforcement of the surface wave with components of stress waves reflected from the back surface. A combination of impact loading and etching makes it possible to investigate the distribution and depths of flaws, their role in the fracture process, and the effect which etching has upon them. The observation on the deformation produced in solids by liquid impact has practical significance in the problem of supersonic aircraft flying through rain and in the erosion of turbine blades moving at high velocity through wet steam.

Effect of Solidification on Molten Material Jet Behavior in Coolant

2014 ◽  
Author(s):  
Yuzuru Iwasawa ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Shimpei Saito ◽  
Hideki Nariai ◽  
...  
Keyword(s):  
Melting Point ◽  
Energy Release ◽  
High Speed ◽  
Heat Removal ◽  
Injection Velocity ◽  
Molten Material ◽  
Breakup Length ◽  
Jet Breakup ◽  
Jet Behavior ◽  
Interfacial Temperature

For the safety design of a Fast Breeder Reactor (FBR), if a Core Disruptive Accident (CDA) occurred hypothetically, it is required to suppress the rapid energy release due to a prompt criticality. Even if the rapid energy release does not occur, there is a possibility that a large amount of fuel melts. Therefore it is important to achieve Post Accident Heat Removal (PAHR). In order to achieve PAHR, it is strongly required that the molten material which is released from a core region gets cool and solidifies in the sodium coolant in a reactor vessel by breaking up. It is considered that the molten fuel is injected into the coolant like a jet. Furthermore, in the actual FBR, the interfacial temperature between the molten fuel jet and the coolant is considered to be lower than the melting point of the molten material. Thus for PAHR in CDA, it is important to understand the interaction between the jet and the coolant in such a condition and to estimate the molten jet behavior quantitatively. In order to estimate quantitatively the effects of the solidification on the molten jet behavior, we carried out the experiment in which a simulant material was injected into a simulant coolant. In the experiment, we used low melting point alloy (Bi -Sn) and water as the simulant molten material and the simulant coolant respectively. In the experiments, we chose the temperature range including the condition that the interfacial temperature was lower than the melting point of the molten material. The jet breakup and the fragmentation behavior of the molten material jet were observed with a high speed video camera. Then the jet breakup length is estimated form the results. We changed the initial interfacial temperature condition by adjusting temperature of the molten material and the coolant. We also changed the jet velocity by adjusting the height of the nozzle tip from the water surface. From the experiment, we found that the jet breakup behavior depends greatly on the interfacial temperature and the injection velocity and that the solidification of a molten material jet and the growth of unstable jet surface, which results from the relative velocity of the jet to the coolant, are in a competitive relation for the jet breakup. We also found that when the molten material jet breaks up into fragments, the breakup length is independent of the initial interfacial temperature and the initial injection velocity.

Investigations of Arc Behavior and Particle Formation in the Wire Arc Spray Process Using High Speed Photography

2000 ◽  
Author(s):  
N.A. Hussary ◽  
J. Heberlein
Keyword(s):  
Thermal Spray ◽  
High Speed ◽  
Imaging System ◽  
Metal Droplet ◽  
Droplet Formation ◽  
Operating Conditions ◽  
Arc Spraying ◽  
High Speed Photography ◽  
Spray Process ◽  
The Wire

Abstract The wire arc spraying process, one of several thermal spray processes, gained a sizable part of the thermal spray market, however, more control is needed for this process to be used for high precision coatings. This study is aimed at investigating the liquid metal droplet formation process in order to identify methods for droplet trajectory control. A high speed Kodak imaging system has been used to observe the droplet formation for different operating conditions. Decreasing the upstream pressure and the current levels lead to the reduction in the asymmetric melting of both anode and cathode. By decreasing the interactions of the large eddy structures with the formed metal agglomerates one can achieve better control of the particle trajectories and jet divergence. Thus, coatings can be obtained with higher definition and improved reliability.

Computational Study of the Air/Fuel Mixture in a Small Spark Ignition Engine

2007 ◽  
Author(s):  
Suzanne Caulfield ◽  
Ryo S. Amano
Keyword(s):  
Fluid Dynamics ◽  
Formation Process ◽  
High Speed ◽  
Computational Study ◽  
Spark Ignition ◽  
Droplet Formation ◽  
Spark Ignition Engine ◽  
Droplet Breakup ◽  
High Speed Photography ◽  
Fuel Delivery

In an effort to understand the fluid dynamics in the droplet formation process, during the fuel delivery portion of operation of a small spark ignition engine, a computational study of the process was undertaken. A combination of high-speed photography and Computational Fluid Dynamics was used to investigate the droplet formation process. Droplets of liquid are stripped from a column of liquid and entrained in a high velocity, cross-flow air stream. This process is known as aerodynamic stripping. This aerodynamic stripping is the process by which fuel is metered and delivered to a spark ignition engine. The condition of the fuel and air mixtures has an impact on the combustion event in the engine. Therefore, a thorough understanding of the fuel delivery process is desirable. This paper details a comprehensive CFD model that was created to explore the possibility of modeling the droplet breakup process. The mesh density required for this analysis was investigated. The accuracy of the predictions was verified by comparing the CFD results with high-speed film taken of the process. The results show that the process can be modeled accurately, provided the correct size mesh is used, and that the predicted droplets compare well with those seen in the film.

scholarly journals Cavity surface wave patterns and general appearance

1970 ◽  
Vol 44 (1) ◽  
pp. 33-49 ◽  
Author(s):  
Christopher Brennen
Keyword(s):  
Boundary Layer ◽  
Surface Wave ◽  
High Speed ◽  
Cavity Surface ◽  
High Speed Photography ◽  
Instability Analysis ◽  
Instability Waves ◽  
Spatial Growth ◽  
Wave Patterns ◽  
General Appearance

Observations were made of the appearance of hydrodynamic cavities behind a series of axisymmetric headforms. Among the phenomena investigated was the transition of the interfacial or separated boundary layer on the cavity surface. The first stage of this process, namely the spatial growth of instability waves could be distinguished by means of high-speed photography. Comparison is made with a theoretical instability analysis.

Experimental Investigation of Liquid Jet Breakup in Cross Flow of Swirling Air Stream

2013 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross-flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach No. 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using MATLAB to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes — bag breakup, column breakup, shear breakup and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15° swirl show reduced breakup length and penetration related to the non-uniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

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