Splashing of a Small Droplet Impinging on a Solid Surface at High Velocity

2000 ◽  
Author(s):  
N. Z. Mehdizadeh ◽  
S. Chandra ◽  
J. Mostaghimi
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Impact Velocity ◽  
Steel Substrate ◽  
Video Camera ◽  
Droplet Impact ◽  
Stainless Steel Surface ◽  
Water Droplets ◽  
Produce Water ◽  
The Impact

Abstract We photographed water droplets (550 μm diameter) as they impacted on a stainless steel surface. We varied droplet impact velocity (10–40 m/s) and the average surface roughness (0.03–0.23 μm) of the steel plates used as test surfaces in our experiments. A piezoelectric droplet generator was used to produce water droplets. The stainless steel substrate was mounted on the end of a rotating arm, giving linear velocities of up to 40 m/s. A CCD video camera was used to photograph droplets impinging on the substrate. By synchronizing the ejection of a single droplet with the position of the rotating arm and triggering of the camera, different stages of droplet impact were photographed. From these photographs we measured the size of droplets as they spread. It was observed that as the impact velocity increased, finger-shape perturbations around the spreading droplet became longer and narrower. At sufficiently high velocities the tips of these fingers detached, producing satellite droplets. Increasing surface roughness was found to promote splashing and reduce the velocity at which splashing was first observed. By increasing surface roughness, both the number of fingers and the maximum extent of spreading were decreased. At high impact velocities the spreading liquid film became so thin that it ruptured in several places.

Boiling during high-velocity impact of water droplets on a hot stainless steel surface

2006 ◽  
Vol 462 (2074) ◽  
pp. 3115-3131 ◽  
Author(s):  
Navid Z Mehdizadeh ◽  
Sanjeev Chandra
Keyword(s):  
Stainless Steel ◽  
Substrate Temperature ◽  
Impact Velocity ◽  
High Velocity ◽  
Steel Surface ◽  
Stainless Steel Surface ◽  
High Velocity Impact ◽  
Water Droplets ◽  
Velocity Impact ◽  
The Impact

High-velocity impact of water droplets (0.55 mm diameter) on a heated stainless steel surface was photographed. To achieve high impact velocities, the test surface was mounted on the rim of a rotating flywheel, giving linear velocities of up to 50 m s −1 . Two cartridge heaters were inserted in the substrate and used to vary substrate temperature. A charge coupled device (CCD) video camera was used to photograph droplets impinging on the substrate. To photograph different stages of droplet impact, the ejection of a single droplet was synchronized with the position of the rotating flywheel and triggering of the camera. Substrate temperature was varied from 100 to 240 °C and the impact velocity from 10 to 30 m s −1 . High-resolution photographs were taken of vapour bubbles nucleating sites inside the thin liquid films produced by spreading droplets. An analytical expression was derived for the amount of superheat required for vapour bubble nucleation as a function of the impact velocity. For a given surface roughness, the amount of superheat needed decreased with impact velocity, which agreed with experimental results. For a fixed impact velocity, the maximum extent of droplet spread increased with substrate temperature.

Effect of Impact Velocity and Substrate Temperature on Boiling of Water Droplets Impinging on a Hot Stainless Steel Surface

Volume 3 ◽  
2004 ◽  
Author(s):  
N. Z. Mehdizadeh ◽  
S. Chandra
Keyword(s):  
Stainless Steel ◽  
Substrate Temperature ◽  
Impact Velocity ◽  
Steel Surface ◽  
Bubble Nucleation ◽  
Test Surface ◽  
Stainless Steel Surface ◽  
Water Droplets ◽  
Droplet Spreading ◽  
The Impact

We photographed high velocity impact of small water droplets (0.55 mm) on a heated stainless steel surface. To achieve high impact velocities the test surface was mounted on the rim of a rotating flywheel, giving linear velocities of up to 50 m/s. Two cartridge heaters were inserted in the substrate and used to vary substrate temperature. A CCD video camera was used to photograph droplets impinging on the substrate. By synchronizing the ejection of a single droplet with the position of the rotating flywheel and triggering of the camera, different stages of droplet impact were photographed. Substrate temperature was varied from 100–240°C and the impact velocity from 10–30 m/s. High-resolution photographs were taken of vapor bubbles nucleating sites inside the thin films produced by spreading droplets. For a given impact velocity, the extent of droplet spreading increased with substrate temperature. The superheat needed to initiate bubble nucleation decreased with impact velocity. We derived an analytical expression for the amount of superheat required for vapor bubble nucleation as a function of impact velocity.

Investigation of Metal Droplet Flattening Behavior after Impacting onto Stainless Steel Substrate

2009 ◽  
Vol 628-629 ◽  
pp. 703-708 ◽  
Author(s):  
Hao Ping Zeng ◽  
Liang Rong Zhu ◽  
Y.Q. Gao ◽  
Wen Ji Xu ◽  
L. Yang ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Stainless Steel ◽  
Impact Velocity ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Metal Droplet ◽  
Spray Forming ◽  
Molten Droplet ◽  
Plasma Spray Forming ◽  
The Impact

During plasma spray forming, the forming quality is directly influenced by the flattening behavior of the droplet impacted onto the substrate, which is determined by the flattening configuration and solidification state of the droplet. In this study, according to the rule of Reynolds number and Peclet number, the flattening behavior of big-size molten droplet impacted onto the substrate with low-speed were experimentally simulated during flattening. The droplets of Sn30Pb70, Zn and ZA12 impacting onto the stainless steel substrate with different velocity were investigated. Splashing degree was introduced to evaluate the flattening profiles of the splats. The relationships between the splashing degree and the impact velocity, Reynolds number and Weber number of the droplet were established. Experimental results show that the flattening and diffusion are impeded by the dynamic viscosity and surface tension of the droplets, and the impeding effects are more remarkable when the impact velocity is lower. The research has a significant ap

Study of CIGS Thin Films Solar Cell P2 Layer Scribing Using UV Laser

2015 ◽  
Vol 764-765 ◽  
pp. 148-152
Author(s):  
Dyi Cheng Chen ◽  
Ming Fei Chen ◽  
Ming Ren Chen
Keyword(s):  
Stainless Steel ◽  
Solar Cell ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Processing System ◽  
Uv Laser ◽  
Cigs Solar Cell ◽  
Laser Apparatus ◽  
The Impact ◽  
Solar Cell Technology

This study will be UV (355nm) laser processing system as a carrier. Using laser direct forming for CIGS solar cell technology P2 layer of stainless steel studied electrode insulated characteristic. To explore the impact of this process on the way to a stainless steel substrate P2 film sizes using its laser different frequency parameters. The experimental results indicated that the electrode pattern of the experiment was similar to that of the simulation result, and the laser process has good results in scribing processing. The analysis results confirm the effectiveness of the laser apparatus when applied to a CIGS solar cell P2 layer of stainless steel.

Comparison studies of the protective properties of silane/polyrhodanine and polyrhodanine/silane bilayer coatings applied on stainless steel

2018 ◽  
Vol 65 (2) ◽  
pp. 190-196 ◽  
Author(s):  
Edyta Owczarek
Keyword(s):  
Stainless Steel ◽  
Photoelectron Spectroscopy ◽  
Steel Surface ◽  
Steel Substrate ◽  
Dip Coating ◽  
Stainless Steel Surface ◽  
Protective Properties ◽  
Content Type ◽  
Anticorrosion Properties ◽  
Bilayer Coatings

Purpose The purpose of this paper is to evaluate and compare the protective, anticorrosion properties of silane- and polyrhodanine-based bilayer coatings pRh/IBTES and IBTES/pRh on an X20Cr13 stainless steel substrate. Design/methodology/approach IBTES/pRh and pRh/IBTES have been coated using the dip-coating method and the cyclic voltammetry technique. The electrochemical measurements have been used to assess the anticorrosion properties of the resulting bilayer coatings. Morphological and chemical characterizations have been performed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Findings The results clearly show that the combination of both the deposits of polyrhodanine and silane yields a more protective structure that affords better protection against corrosion with time. The best barrier properties are achieved by the substrates coated with polyrhodanine film upon which silane is subsequently adsorbed – the pRh/IBTES bilayer coating. Originality/value The paper reveals that the procedure of modification of silane films with polyrhodanine had a marked effect on the anti-corrosive performance of the obtained two types of bilayers coatings (pRh/IBTES, IBTES/pRh) applied on a stainless steel surface. The coating where polyrhodanine was first electrodeposited on the steel surface and then the silane layer adsorbed (pRh/IBTES) achieved the best protective properties.

scholarly journals Multi-objective optimization and analysis for laser beam cutting of stainless steel (SS304) using hybrid statistical tools GA-RSM

2021 ◽  
Vol 1201 (1) ◽  
pp. 012030
Author(s):  
A D Tura ◽  
H B Mamo ◽  
D G Desisa
Keyword(s):  
Genetic Algorithm ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Laser Beam ◽  
Response Surface ◽  
Focal Point ◽  
Cutting Speed ◽  
Machining Parameters ◽  
Multi Objective ◽  
The Impact

Abstract A laser beam machine is a non-traditional manufacturing technique that uses thermal energy to cut nearly all types of materials. The quality of laser cutting is significantly affected by process parameters. The purpose of this study is to use a genetic algorithm (GA) in conjunction with response surface approaches to improve surface roughness in laser beam cutting CO2 with a continuous wave of SS 304 stainless steel. The effects of the machining parameters, such as cutting speed, nitrogen gas pressure, and focal point location, were investigated quantitatively and optimized. The tests were carried out using the Taguchi L9 orthogonal mesh approach. Analysis of variance, main effect plots, and 3D surface plots were used to evaluate the impact of cutting settings on surface roughness. A multi-objective genetic algorithm in MATLAB was used to achieve a minimum surface roughness of 0.93746 μm, with the input parameters being 2028.712 mm/m cutting speed, 11.389 bar nitrogen pressure, and a focal point position of - 2.499 mm. The optimum results of each method were compared, as the results the response surface approach is less promising than the genetic algorithm method.

Sign in / Sign up

Export Citation Format

Share Document