In most cases, turbulence in the liquid, cavitation in the nozzle, and aerodynamic interaction with the surrounding gas contribute to atomization. In all cases, atomization occurs when the magnitude of the disruptive force only exceeds the consolidated surface tension force. Many of the larger droplets produced at the first break in the jet or liquid plate are unstable and undergo further disintegration in smaller droplets. Therefore, the droplet size characteristics of an aerosol are determined not only by the droplet sizes produced by primary atomization, but also by the extent to which the largest of these droplets disintegrates further during secondary atomization.
Rotary atomizers use centrifugal energy to achieve the high relative speed between air and liquid required for good atomization. A rotating surface is used that can take the form of a flat disc, a blade disc, a cup, a bell, or a slot wheel. Figure 2d shows a simple form of rotary atomizer, consisting of a rotating disc with means to insert liquid into the center. The liquid flows radially over the disc and is removed from the periphery at high speed. Different atomization mechanisms are observed with a rotating flat disk, depending on the fluid flow and the speed of rotation of the disc. At low flow rates, the liquid is discharged from the edge of the disc in the form of drops of a fairly uniform size.
In this article, the mechanism of interaction of solid, liquid and gas in the nebulization process of superalloy is studied and influential factors and the control of dust characteristics in the fusion, spheroidism and coagulation process are studied. CFD’s numerical calculation method, a commercial ANSYS software that is fluid, is used to simulate the process of preparing the VIGA nickel alloy powder It takes a lot for an engine to work, but nothing would be possible without the atomization of liquid fuels for automobiles.
Since the current field in the actual nebulization process takes the nozzle axis as the center line and shows an asymmetric distribution, the three-dimensional structure of the actual central symmetry is simplified as a two-dimensional asymmetric structure. The simplified geometry model of the VIGA aerosol equipment is shown in Fig. Since the calculation area is two-dimensional asymmetric geometry, to reduce the amount of calculation, the half-model is selected as the calculation area and the game software is used to cut the river basin.
In summary, it is important to recognize that no parameter can fully define a drop size distribution, two sprays are not comparable just because they have the same VMD or SMD. However, if a Rosin-Rammler distribution is assumed, the distribution of drop sizes in an aerosol can be expressed by two parameters, a representative or average diameter and a measure of the drop size distribution. After many years of working on metallurgy and dust atomization, it is very encouraging to see the remarkable current revival in the field. The ‘classical’ PM industry for sintered parts did not attract much research interest in the UK in the 1980s and 1990s, but in the last 20 years it was the first time that MIM and HIP were performed and, more recently, AM or three-dimensional impression . This has led to a massive increase in industrial research and investment in PM worldwide over the past decade. These new PM branches have very different requirements for the metal powders they use.
After a heat treatment at 300 ° C for 4 hours, the powders consisted of a single phase η ‘Cu6Sn5. The Cu6Sn5 phase powders obtained can be used in high temperature applications, such as intermetallic balls for integrated chip interconnections. The most practical atomizers cause falls in the size range of a few microns to several hundred microns. A simple boron nitride nozzle method to illustrate the distribution of droplet sizes in an aerosol is to draw a histogram in which each ordinate represents the number of droplets whose dimensions fall between the limits D – ΔD / 2 and D + ΔD / 2. As ΔD becomes smaller, the histogram takes the form of a frequency distribution curve, provided it is based on sufficiently large samples.
If the interior temperature subsequently fell below 227 ° C, the coagulation of the eutectic η + β would have occurred after peritectural coagulation. Electrothermal atomizers provide greater sensitivity because samples are rapidly atomized and have a longer residence time compared to AAS flame systems, which means that more of the sample is analyzed at the same time. This method can also be used for quantitative determinations based on signal height and surface. Electrothermal atomization also offers the advantage of a smaller sample size and reduced spectral interference due to the high temperature of the graphite furnace. However, electrothermal atomizers have drawbacks, including a slow measurement time due to the required heating and cooling of the system and a limited analytical range. In addition, the analyte and matrix diffuse into the graphite tube, and over time the tube must be replaced, increasing maintenance and costs associated with electrothermal atomization.