Experimental study on the effect of surface temperature and Weber number to spreading ratio of multiple droplets on a horizontal surface

Author(s):  
Ardi Wiranata ◽  
Indro Pranoto ◽  
Windy H. Mitrakusuma ◽  
Deendarlianto ◽  
Samsul Kamal
Soft Matter ◽  
2019 ◽  
Vol 15 (5) ◽  
pp. 1017-1026 ◽  
Author(s):  
S. Jowkar ◽  
M. R. Morad

The focus of the present experimental study is on the maximum height of drop bouncing after impinging on flat and semicylindrical concave surfaces, in particular in terms of surface temperature.


2018 ◽  
Vol 154 ◽  
pp. 01114 ◽  
Author(s):  
Aria Riswanda ◽  
Indro Pranoto ◽  
Deendarlianto ◽  
Indarto ◽  
Teguh Wibowo

Multiple droplets are drops of water that continuously dropped onto a surface. Spray cooling is an application of the use of droplet on a cooling system. Spray cooling is usually used in a cooling system of electronic devices, and material quenching. In this study, correlations between Weber number and surface temperature decrease rate during multiple droplets impingement are investigated and analyzed. Visualization process is used to help determine the evaporation time of droplets impingement by using high speed camera. Induction stove is used to maintain a stainless steel surface temperature at 120°C, 140°C, and 160°C. The Weber number was varied at 15, and 52.5 to simulate low and medium Weber number. The result of this study shows that increase in Weber number does not increase the temperature decrease rate noticeably. Whereas the Weber number decrease the time required for surface temperature to reach its lowest surface temperature. It was also found that for low and medium Weber number, Weber number affect the evaporation time of multiple droplets after impingement.


Author(s):  
Ф.В. Роньшин ◽  
Ю.А. Дементьев ◽  
Е.А. Чиннов

An experimental study of drop formation in narrow horizontal microchannels with rectangular cross section and a height from 50 to 150 micrometers was performed. It is shown that in these channels there is a new flow regime when drops moving along the microchannel, which are vertical liquid bridges. Three mechanisms of the formation of such drops are distinguished: the formation directly near the liquid nozzle, the separation of droplets from the liquid moving along the side walls of the channel, and due to the destruction of strongly deformed drops and horizontal liquid bridges. It was found that the deformation of drops increases with an increase in the Weber number. It is shown that when the first critical value of the Weber number is reached, the drops begin to deform, and when the second Weber number is reached, they break.


2019 ◽  
Vol 72 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Liang Yu ◽  
Biao Ma ◽  
Man Chen ◽  
He Yan Li ◽  
Jikai Liu

Purpose This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG). Design/methodology/approach This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration. Findings The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically. Originality/value This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.


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