Stereographic Backlit Imaging and Bubble Identification From a Plunging Jet With Floor Interactions

2021 ◽  
Author(s):  
Roy A. Pillers ◽  
Theodore J. Heindel
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
Primary Source ◽  
Breaking Waves ◽  
Bubble Plume ◽  
Shape Estimation ◽  
Fish Farms ◽  
Automated Identification ◽  
Set Up ◽  
The Impact

Abstract Plunging jets have been extensively studied for their relatively simple set-up but complex multiphase interactions. This phenomenon includes gas carry-under and mixing, which occurs when shear effects between the plunging liquid jet and surrounding gas are sufficient to entrain gas at the impact site. Previous investigations typically assume the floor has an infinite depth and neglect compressive effects caused by the jet interacting with the catch tank floor. While this assumption is ideal for breaking waves in the middle of the ocean, many other applications have to contend with floor effects. These include waterfalls, wastewater treatment, dams, fish farms, mineral separation, and molten metal pouring. It is hypothesized that floor interactions will significantly affect the multiphase flow hydrodynamics, especially in places where the uninhibited jet would approach or pass the floor region. Using a large catch tank with an adjustable floor region designed to hold a constant water level, data were collected using high-speed backlit stereographic imaging to capture and compare the effects of three separate tank depths with those found using an infinite pool assumption. To identify bubbles in each stereographic projection, a uniform bubble recognition procedure was developed that was used across all data sets. This allowed for the automated identification of bubble entrainment regions, which could be compared with different flow conditions. Preliminary results are inconclusive as to the effects of the floor region on the bubble plume dynamics; however, the results showed consistent measurements between trials and the two stereographic cameras, implying the time variation of the jet dynamics was the primary source of uncertainty in the results and not the identification procedure. Therefore, the identification methods have provided a method for plume volume and shape estimation, which will be used in future studies using 3D imaging techniques.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

Analysis of Dynamic Response of Simply-Supported Girder Bridge in High-Speed Railway Based on the Moving Rows Mass-Spring Model

2012 ◽  
Vol 193-194 ◽  
pp. 919-924
Author(s):  
Jin Feng Wu ◽  
Zhi Jun Zhang ◽  
Xiao Zhen Li
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Spring Model ◽  
Simply Supported ◽  
Mass Spring Model ◽  
Girder Bridge ◽  
Set Up ◽  
Mass Spring ◽  
The Impact ◽  
Bridge System

The vibration theory of beam and D’Alembert principle are used to set up vehicle-bridge system for a simply-supported girder bridge under the moving rows mass-spring model. The kinematic equations of vehicle and bridge are derived separately. And with the force balanced relationship and the displacement compatibility conditions between wheels and rail, the equations of vehicle-bridge system are established. A calculating program is complicated with MATLAB language and solved by Newmark-β method. Results show that the effect of the damping ratio on the impact factor is significant and running speed of the vehicle is one of the main actors resulting in vibration of the system.

scholarly journals Liquid Propane Injection in Flash-Boiling Conditions

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6257
Author(s):  
Łukasz Jan Kapusta ◽  
Jakub Bachanek ◽  
Changzhao Jiang ◽  
Jakub Piaszyk ◽  
Hongming Xu ◽  
...  
Keyword(s):  
High Speed ◽  
Saturation Pressure ◽  
Injection Pressure ◽  
Spray Angle ◽  
Liquid Propane ◽  
Spray Tip Penetration ◽  
Commercial Gasoline ◽  
Flash Boiling ◽  
Set Up ◽  
The Impact

This study aimed to investigate the influence of flash-boiling conditions on liquid propane sprays formed by a multi-hole injector at various injection pressures. The focus was on spray structures, which were analysed qualitatively and quantitatively by means of spray-tip penetration and global spray angle. The effect of flash boiling was evaluated in terms of trends observed for subcooled conditions. Propane was injected by a commercial gasoline direct injector into a constant volume vessel filled with nitrogen at pressures from 0.1 MPa up to 6 MPa. The temperature of the injected liquid was kept constant. The evolution of the spray penetration was observed by a high-speed camera with a Schlieren set-up. The obtained results provided information on the spray evolution in both regimes, above and below the saturation pressure of the propane. Based on the experimental results, an attempt to calibrate a simulation model has been made. The main advantage of the study is that the effects of injection pressure on the formation of propane sprays were investigated for both subcooled and flash-boiling conditions. Moreover, the impact of the changing viscosity and surface tension was limited, as the temperature of the injected liquid was kept at the same level. The results showed that despite very different spray behaviours in the subcooled and flash-boiling regimes, leading to different spray structures and a spray collapse for strong flash boiling, the influence of injection pressure on propane sprays in terms of spray-tip penetration and spray angle is very similar for both conditions, subcooled and flash boiling. As for the numerical model, there were no single model settings to simulate the flashing sprays properly. Moreover, the spray collapse was not represented very well, making the simulation set-up more suitable for less superheated sprays.

Experimental Investigation of Water Entry Impact on Hydrophobic Surfaces

2015 ◽  
Author(s):  
Bulent Guzel ◽  
Fatih C. Korkmaz
Keyword(s):  
Experimental Investigation ◽  
Flow Separation ◽  
High Speed ◽  
Water Entry ◽  
Air Entrapment ◽  
Hydrophobic Surfaces ◽  
Blunt Bodies ◽  
Drop Tests ◽  
Set Up ◽  
The Impact

The results of an experimental investigation on hull bottom slamming of three different geometries, sphere, cylinder and wedge, with hydrophobic surfaces are presented. In water entry of blunt bodies, different fluid dynamics phenomena like jet formation, cavity formation, water splashing, flow separation on solid surfaces and air entrapment between solid and liquid surface have been studied for decades. Our study is aimed at understanding and modeling the dynamics of slamming under an extended range of parameters including hydrophobic surfaces. In this study, drop tests have been set up for hull bottom slamming by dropping a body from various heights toward water surface. From digital images captured using a high speed camera, flow separation and water splashing at different velocities are observed and spreading diameters and entrance characteristics are measured during the impact process. At the same time, we measure the pressure distribution on the surface of the bodies during impact via strain gages.

Backlit Imaging of a Circular Plunging Jet With Floor Interactions

2020 ◽  
Author(s):  
Roy A. Pillers ◽  
Theodore J. Heindel
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Air Entrainment ◽  
Ocean Waves ◽  
Jet Flows ◽  
Small Scale ◽  
Bubble Plume ◽  
Plunging Jets ◽  
Compression Effects ◽  
The Impact

Abstract Plunging jets occur when a liquid stream enters a slower moving or stationary liquid body after first passing through a gaseous region. The most commonly studied plunging jet structure is that of water entering water. Plunging jets have been studied in order to understand and model mixing and transport from the atmosphere into the liquid. Shear forces at the edge of the jet cause air entrainment both in the free jet and at the impact point on the pool surface. Plunging jet applications range from large scale environments, such as ocean waves, waterfalls, wastewater treatment, and dams, to small scale environments, such as liquid-gas fuel mixing, mineral separation, and molten metal pouring. The majority of the literature today involve facilities designed to approximate an infinite liquid pool; few of these studies take into account the compression effects prevalent in several of the real systems. Therefore, a tank has been developed for the visualization of plunging jet flows with varying pool depth. This study involved the creation of a 32 cm by 32 cm, 91.4 cm deep rectangular acrylic tank with an interior adjustable acrylic bottom for the visualization of plunging jet flows with bottom compression effects. The pool height was held constant using a secondary tank with an overflow weir. In this study high-speed backlit images were taken of the plunging jet region. Preliminary results indicate that there is a significant change in both the shape and estimated entrained air volume when the plunging jet is subjected to compression effects. This is attributed to the plate spreading the bubble plume and allowing for easier bubble rise.

Numerical Study on High-Speed Impact Between a Water Droplet and a Deformable Solid Surface

2012 ◽  
Author(s):  
Yongqiang Han ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Solid Surface ◽  
Water Droplet ◽  
High Speed ◽  
Numerical Study ◽  
Contact Radius ◽  
Deformable Solid ◽  
Theoretical Predictions ◽  
Steam Turbine Blade ◽  
Set Up ◽  
The Impact

In this study an axisymmetric model is set up to study the impact of a spherical water droplet with a planar deformable solid surface using the Lagrange-Euler coupling method which is based on a penalty formulation. The diameter and velocity of the droplet are 0.4 mm and 500 m/s respectively, while the solid is a kind of steam turbine blade material. The generated pressure distribution in the droplet and its variation with time, the formation of lateral jet, the deformation and stress distribution in the solid are obtained and investigated. It is shown that the compressibility of the droplet and the solid plays a significant role during the impact. The water-hammer pressure and the maximum contact edge pressure are calculated and in good agreement with the existing theoretical predictions. The calculated contact radius for shock departure is larger than that of the conventional theoretical prediction, which is analyzed and attributable to the radial motion of the liquid in the compressed region. The formation of the high-speed lateral jet is calculated and the time for the observable jetting is much later than that of the shock departure. This delay is discussed and the reason needs more research. The pressure of the contact edge region remains highest even after a considerable time of shock departure and lateral jetting. In the mean time, a saucer-shaped depression is generated in the center of the impact. The stress waves in solid move faster even before shock departure in the liquid. This causes disturbance of the solid surface before the high-speed lateral jetting and provides site for the scouring action of it, and subsequently may cause material damage and erosion.

Vibration Tests of the Processing Shaft Cascading Structure in High Speed and High Precision PCB Drilling Machine

2012 ◽  
Vol 246-247 ◽  
pp. 1263-1267
Author(s):  
Feng Gong ◽  
Yan Ping Tan ◽  
Ji Bin Li
Keyword(s):  
High Precision ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Drilling Machine ◽  
Guide Rail ◽  
Basic Part ◽  
Free Mode ◽  
Set Up ◽  
Vibration Tests ◽  
The Impact

It is necessary to study the dynamic characteristics of the structure of processing shaft cascade in high speed and high precision PCB drilling machine because of its great impact on the drilling precision. As a basic part, the dynamic characteristics of the structure of cascade depend on the dynamic characteristics of the Z-axis floor. Based on it, firstly, the free mode test is conducted on the Z-axis floor, the same as the modes that it is just set up on the guide rail, the cascade is added and the motor spindle has been added on the Z-axis floor. From the four situations, the modal pa-rameters are gained in the tests. Then the ODS test is carried out and the vibration is analyzed in the real situation. The vibration tests of the cascade comprehensively acquire dynamic characteristics from the Z-axis floor before being assembled to the Z-axis floor which is entirely cascaded on the Z axis. Acknowledge of the impact that the vibrations bring to the drilling precision of the drilling machine provides the direction of improving the structure.

scholarly journals The Influence of Electronic Word-of-Mouth Communication on the Behaviour of the Theatre Audience Analysed Through the Kosovo Example

2017 ◽  
Vol 7 (2) ◽  
pp. 26
Author(s):  
Shpresë Mulliqi
Keyword(s):  
Social Networks ◽  
Interpersonal Communication ◽  
Information And Communication Technologies ◽  
Word Of Mouth ◽  
Online Communication ◽  
Primary Source ◽  
Electronic Word Of Mouth ◽  
The Social ◽  
Set Up ◽  
The Impact

The expansion of Internet, the development of the new information and communication technologies as well as social networks have revolutionized the social interaction as they have enabled individuals to quickly and conveniently get in touch with each other. The interaction performed online, defined as online interpersonal communication, or the Electronic word-of-mouth (eWOM), as seen in numerous research papers, impacted the consumer behaviour. This paper analyses audience behaviour when making decisions vis-à-vis cultural offers presented in social networks. Although the issue of subjectivity in relation to the offered content in these platforms is set up as a determining factor for using e-WoM and the social networks, the main results suggest that both have been used by audience as a primary source of information when deciding to visit a cultural event. Moreover social networks have been described as places where information is not headed by clienteles, thus significant, customer friendly and trustworthy, despite the fact that all these information are based on subjective impressions of each social network user. The limited number of research on the impact of online communication of the theatre audience has been perceived as an obstacle, as there are no guiding direction how we should do it, and as a challenge, given that through this research we will set the baseline for future researches that will analyse the effectiveness of eWoM.

scholarly journals High-Speed Visualization of Very Large High-Resolution Simulations for Air Hazard Transport and Dispersion

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 920
Author(s):  
Olivier Oldrini ◽  
Sylvie Perdriel ◽  
Patrick Armand ◽  
Christophe Duchenne
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Management Framework ◽  
Emergency Situations ◽  
Noxious Substance ◽  
Multi Level ◽  
Set Up ◽  
Effective Visualization ◽  
The Impact ◽  
Atmospheric Release

In the case of an atmospheric release of a noxious substance, modeling remains an essential tool to assess and forecast the impact of the release. The impact of such situations on populated, and hence built-up, areas is of the uttermost importance. However, modeling on such areas requires specific high-resolution approaches, which are complex to set up in emergency situations. Various approaches have been tried and evaluated: The EMERGENCIES and EMED project demonstrated an effective strategy using intensive parallel computing. Large amounts of data were produced that proved initially to be difficult to visualize, especially in a crisis management framework. A dedicated processing has been set up to allow for rapid and effective visualization of the modeling results. This processing relies on a multi-level tiled approach initiated in web cartography. The processing is using a parallel approach whose performances were evaluated using the large amounts of data produced in the EMERGENCIES and EMED projects. The processing proved to be very effective and compatible with the requirements of emergency situations.

scholarly journals The Influence of Electronic Word-of-Mouth Communication on the Behaviour of the Theatre Audience Analysed Through the Kosovo Example

2017 ◽  
Vol 3 (2) ◽  
pp. 26
Author(s):  
Shpresë Mulliqi
Keyword(s):  
Social Networks ◽  
Interpersonal Communication ◽  
Information And Communication Technologies ◽  
Word Of Mouth ◽  
Online Communication ◽  
Primary Source ◽  
Electronic Word Of Mouth ◽  
The Social ◽  
Set Up ◽  
The Impact

The expansion of Internet, the development of the new information and communication technologies as well as social networks have revolutionized the social interaction as they have enabled individuals to quickly and conveniently get in touch with each other. The interaction performed online, defined as online interpersonal communication, or the Electronic word-of-mouth (eWOM), as seen in numerous research papers, impacted the consumer behaviour. This paper analyses audience behaviour when making decisions vis-à-vis cultural offers presented in social networks. Although the issue of subjectivity in relation to the offered content in these platforms is set up as a determining factor for using e-WoM and the social networks, the main results suggest that both have been used by audience as a primary source of information when deciding to visit a cultural event. Moreover social networks have been described as places where information is not headed by clienteles, thus significant, customer friendly and trustworthy, despite the fact that all these information are based on subjective impressions of each social network user. The limited number of research on the impact of online communication of the theatre audience has been perceived as an obstacle, as there are no guiding direction how we should do it, and as a challenge, given that through this research we will set the baseline for future researches that will analyse the effectiveness of eWoM.

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