کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
11008881 1840429 2019 64 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Spread and recoil of liquid droplets impacting on solid surfaces with various wetting properties
ترجمه فارسی عنوان
گسترش و دفع مایع قطرات موثر بر روی سطوح جامد با خواص خیس شدن مختلف
کلمات کلیدی
جریان دو مرحله ای، تاثیر قطره، اثرات خیس شدن،
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فناوری نانو (نانو تکنولوژی)
چکیده انگلیسی
Thermally sprayed coatings are manufactured by molten or semi-molten droplets impinging onto the target substrate. The properties of coatings created (porosity, conductivity, cracks, ...) depend largely on the dynamics of the droplets which is an outcome of joint aspects, such as properties of liquid droplet and surface wettability. The present work investigates the normal impact of liquid droplets (molten ceramic or metallic droplets) onto dry solid surfaces of various wetting properties. Use is made of the Volume-Of-Fluid (VOF) interface tracking method with a single set of mass and momentum conservation equations. The wettability of a solid surface, characterised by a contact angle, is taken as part of the boundary conditions in the Smooth VOF algorithm. Introducing the dimensionless time t* = tV0/D0 for a droplet with the initial speed V0 and initial diameter D0, its spread factor ξ (= D/D0) is found to be proportional to the square root of t* when 0.2 < (t*)1/2 < 0.35. There exists a transitional zone where the changing rate of the spread factor decreases with the ascending contact angle. In addition, the wetting effects on the spreading can be ignored when 0.2 < (t*)1/2 < 0.35 but have to be accounted for once (t*)1/2 < 0.2. Further, the droplet jetting time is found to be inversely proportional to the impact velocity but not affected by the solid surface wettability. Finally, in the recoil stage, the influences of Weber number, Ohnesorge number and contact angle are studied; in particular, the spread factor ξ turns out to be well described by a second-order polynomial equation for t*≥0.5We.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface and Coatings Technology - Volume 357, 15 January 2019, Pages 140-152
نویسندگان
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