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.

Diagnostic Development for Control of Wire-Arc Spraying

1997 ◽  
Author(s):  
J. Sheard ◽  
J. Heberlein ◽  
K. Stelson ◽  
E. Pfender
Keyword(s):  
Molten Metal ◽  
High Speed ◽  
Metal Droplet ◽  
Arc Spraying ◽  
Voltage Fluctuations ◽  
Arc Voltage ◽  
Spray Process ◽  
Arc Spray ◽  
Labview Software ◽  
The Wire

Abstract This research has focused on characterization of the wire arc spray process with the goal of achieving improved process controls. Arc voltage and current traces have been analyzed on-line using an oscilloscope and a personal computer with LabView software. The characteristic features of the arc voltage fluctuations are correlated with the molten metal droplet formation process using a high speed Laser Strobe video system operating in synchronization with the oscilloscope trigger. Voltage minima occur when larger globules of molten metal leave the wire tip. Analysis of the voltage fluctuations indicate that they are neither random nor periodic, and that they can be described based on chaos theory. This approach may be used for achieving a further understanding of the dynamic nature of the process, and for the development of control algorithms.

Forensic Uncertainty Quantification for Experiments on the Explosively Driven Motion of Particles

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Kyle Hughes ◽  
S. Balachandar ◽  
Nam H. Kim ◽  
Chanyoung Park ◽  
Raphael Haftka ◽  
...  
Keyword(s):  
Uncertainty Quantification ◽  
High Speed ◽  
Early Time ◽  
Operating Conditions ◽  
Quality Data ◽  
High Speed Photography ◽  
Particle Array ◽  
X Ray Imaging ◽  
Drag Models ◽  
Air Force Research Laboratory

Six explosive experiments were performed in October 2014 and February of 2015 at the Munitions Directorate of the Air Force Research Laboratory with the goal of providing validation-quality data for particle drag models in the extreme regime of detonation. Three repeated single particle experiments and three particle array experiments were conducted. The time-varying position of the particles was captured within the explosive products by X-ray imaging. The contact front and shock locations were captured by high-speed photography to provide information on the early time gas behavior. Since these experiments were performed in the past and could not be repeated, we faced an interesting challenge of quantifying and reducing uncertainty through a detailed investigation of the experimental setup and operating conditions. This paper presents the results from these unique experiments, which can serve as benchmark for future modeling, and also our effort to reduce uncertainty, which we dub forensic uncertainty quantification (FUQ).

scholarly journals Simultaneous Pressure Measurement and High-Speed Photography Study of Cavitation in a Dynamically Loaded Journal Bearing

1993 ◽  
Vol 115 (1) ◽  
pp. 88-95 ◽  
Author(s):  
D. C. Sun ◽  
D. E. Brewe ◽  
P. B. Abel
Keyword(s):  
Pressure Measurement ◽  
Cavitation Bubble ◽  
High Speed ◽  
Journal Bearing ◽  
Operating Conditions ◽  
High Speed Photography ◽  
Pressure Data ◽  
Oil Film ◽  
Dynamically Loaded ◽  
Insight Into

Cavitation of the oil film in a dynamically loaded journal bearing was studied using high-speed photography and pressure measurement simultaneously. Comparison of the visual and pressure data provided considerable insight into the occurrence and non-occurrence of cavitation. It was found that (1), cavitation typically occurred in the form of one bubble with the pressure in the cavitation bubble close to the absolute zero; and (2), for cavitation-producing operating conditions, cavitation did not always occur; with the oil film then supporting a tensile stress.

scholarly journals Kinematic Analysis of a Clamp-Type Picking Device for an Automatic Pepper Transplanter

Agriculture ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 627 ◽  
Author(s):  
Md Nafiul Islam ◽  
Md Zafar Iqbal ◽  
Mohammod Ali ◽  
Milon Chowdhury ◽  
Md Shaha Nur Kabir ◽  
...  
Keyword(s):  
Kinematic Analysis ◽  
High Speed ◽  
Model Simulation ◽  
Mechanical Damage ◽  
Maximum Velocity ◽  
Operating Conditions ◽  
High Speed Photography ◽  
Virtual Model ◽  
Significant Difference ◽  
Simulation And Validation

Pepper is one of the most vital agricultural products with high economic value, and pepper production needs to satisfy the growing worldwide population by introducing automatic seedling transplantation techniques. Optimal design and dimensioning of picking device components for an automatic pepper transplanter are crucial for efficient and effective seedling transplantation. Therefore, kinematic analysis, virtual model simulation, and validation testing of a prototype were conducted to propose a best-suited dimension for a clamp-type picking device. The proposed picking device mainly consisted of a manipulator with five grippers and a picking stand. To analyze the influence of design variables through kinematic analysis, 250- to 500-mm length combinations were considered to meet the trajectory requirements and suit the picking workspace. Virtual model simulation and high-speed photography tests were conducted to obtain the kinematic characteristics of the picking device. According to the kinematic analysis, a 350-mm picking stand and a 380-mm manipulator were selected within the range of the considered combinations. The maximum velocity and acceleration of the grippers were recorded as 1.1, 2.2 m/s and 1.3, 23.7 m/s2, along the x- and y-axes, respectively, for 30 to 90 rpm operating conditions. A suitable picking device dimension was identified and validated based on the suitability of the picking device working trajectory, velocity, and acceleration of the grippers, and no significant difference (p ≤ 0.05) occurred between the simulation and validation tests. This study indicated that the picking device under development would increase the pepper seedling picking accuracy and motion safety by reducing the operational time, gripper velocity, acceleration, and mechanical damage.

Study on the Arc Shape in the Wire Arc Spray Process

2010 ◽  
Vol 154-155 ◽  
pp. 109-112
Author(s):  
Jia Ying Zhang ◽  
Bin Shi Xu
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Digital Camera ◽  
Wire Arc Spray ◽  
Properties Of Coatings ◽  
Spray Process ◽  
Arc Spray ◽  
Arc Shape ◽  
The Wire ◽  
Metal Wires

Being the heat source of arc spray, the characteristics of arc are of importance for properties of coatings. In this paper, the arc shape in the wire arc spray process was analyzed in the aid of high-speed digital camera. It is testified that the arc has the elliptical shape. This type of shape is favorable for heating the metal particles. The arc isn’t always in burning state and it is extinguished frequently. There are two kinds of reasons for arc extinguish. The first one is that the two metal wires short circuit. The second one is that the imperfect melted metal stretches the arc long, and then this part melted and broken away from the metal wires’ tips. If we can control the metal wires state, the properties of coatings will be improved.

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.

A New Type Laser Imaging System of Underwater Wake Bubbles

2014 ◽  
Vol 543-547 ◽  
pp. 2505-2508
Author(s):  
Xi Zhan Liu ◽  
Yan Bo Xue
Keyword(s):  
High Speed ◽  
Imaging System ◽  
Laser Sheet ◽  
High Speed Photography ◽  
Test Results ◽  
Laser Imaging ◽  
Technical Requirements ◽  
Wide Range ◽  
New Type ◽  
Wake Zone

Considering the difficulties in the wake bubbles imaging, a wake bubbles measurement system was presented based on the combination of high speed photography and laser sheet scanning technology. In this system, laser sheet was used to illuminate the wake zone to avoid the image stacking of bubbles. Because the particle size of bubbles was in a wide range (10~500um), three switchable magnification lenses were designed for the bubbles imaging. the test results show that the image quality is good and this system satisfies technical requirements.

An Artistic Approach to Thermal Spray

2016 ◽  
Vol 879 ◽  
pp. 15-28 ◽  
Author(s):  
M. Jeandin ◽  
F. Borit ◽  
N. Fabrègue ◽  
G. Rolland ◽  
F. Delloro
Keyword(s):  
Thermal Spray ◽  
Automotive Industry ◽  
High Speed ◽  
Temperature Sensitive ◽  
X Ray ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Industrial Sectors ◽  
The Arts ◽  
Contemporary Artist

“Art is everywhere” to quote Ben, a renowned French contemporary artist. However, there are some areas in which art is more prevalent. Thermal spray is one of them, as this presentation seeks to demonstrate. For this, each of the arts (according to their official classification) is shown to correspond to a specific key point of the thermal spray process for coating: e.g., coating build-up, additive manufacturing, deposition onto brittle and/or temperature sensitive materials (glass, wood, fabrics, polymers), powder optimization, and adhesion. Both modeling and experimental aspects are discussed, focusing on the study of particle-to-particle or particle-to-substrate interfaces, shock phenomena and advanced investigation techniques such as X-ray microtomography or high-speed instrumentation. Plasma spray and cold spray provide the relevant examples that this contribution elaborates. They relate to different industrial sectors such as aircraft-aerospace, luxury, biomedical and the automotive industry. Beyond anecdotal evidence, the discussion aims to show that an artistic approach to thermal spray does help to understand better this powerful coating process.

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.

Random Behavior of Kerosene Spray Autoignition in Crossflow

2016 ◽  
Author(s):  
Yongsheng Zhao ◽  
Chi Zhang ◽  
Yuzhen Lin
Keyword(s):  
High Speed ◽  
Flow Reactor ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
High Speed Photography ◽  
Primary Analysis ◽  
Photoelectric Detection ◽  
Random Behavior ◽  
Gauss Distribution ◽  
Autoignition Delay

Based on the flow reactor with rectangle cross-section, this paper studies the spray autoignition characteristics of liquid kerosene injected into air crossflow under high temperature and high pressure conditions. Millisecond-level kerosene injection, millisecond-level photoelectric detection, and high speed photography record experiment techniques are adopted in this research. The operating conditions of this research are as follows: 2.3MPa inlet pressure, 917K inlet temperature, fuel/ air momentum ratio of 52, and Weber number of 355. Photoelectric sensor and photomultiplier equipped with CH filter are used to get the autoignition delay time (ADT). A total of 320 experiments are conducted under the same operating conditions in order to obtain the random ADT probability distribution. The high speed photography is utilized to observe and record the developing process of spray autoignition of kerosene. The results show that the ADT varies from 2.5–5.5millisecond (ms) in the above operating conditions, and confirm the existence of the random behavior of kerosene spray autoignition in the crossflow. These random behaviors of ADT can be correlated well with Gauss distribution. The primary analysis shows that the random behavior stems from the random distributions in the diameter and dispersion due to intrinsic turbulence breakup and transportation which dominate the characteristics of spray autoignition.

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