Search results
Results From The WOW.Com Content Network
Surface tension is an important factor in the phenomenon of capillarity. Surface tension has the dimension of force per unit length, or of energy per unit area. [3] The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to ...
The ASME definition of a pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. [2]The Australian and New Zealand standard "AS/NZS 1200:2000 Pressure equipment" defines a pressure vessel as a vessel subject to internal or external pressure, including connected components and accessories up to the connection to external ...
(σ: surface tension, ΔP max: maximum pressure drop, R cap: radius of capillary) Later, after the maximum pressure, the pressure of the bubble decreases and the radius of the bubble increases until the bubble is detached from the end of a capillary and a new cycle begins. This is not relevant to determine the surface tension. [3]
The positions are primarily driven by surface tension. [ 2 ] : 1 The liquids tend to adhere to the walls and leave a gaseous bubble in the center of the vessel. [ 3 ] : 2 Propellant management devices (PMDs) are required to provide gas-free operation of the engine.
For the thin-walled assumption to be valid, the vessel must have a wall thickness of no more than about one-tenth (often cited as Diameter / t > 20) of its radius. [4] This allows for treating the wall as a surface, and subsequently using the Young–Laplace equation for estimating the hoop stress created by an internal pressure on a thin-walled cylindrical pressure vessel:
In physics, the Young–Laplace equation (/ l ə ˈ p l ɑː s /) is an algebraic equation that describes the capillary pressure difference sustained across the interface between two static fluids, such as water and air, due to the phenomenon of surface tension or wall tension, although use of the latter is only applicable if assuming that the wall is very thin.
To change the surface tension, one can apply a surfactant to the capillary walls. The contact angles vary by sudden expansion or contraction within the device channels. A positive capillary pressure represents a valve on the fluid flow while a negative pressure represents the fluid being pulled into the microchannel. [3]
The Laplace pressure is determined from the Young–Laplace equation given as [2] = (+), where and are the principal radii of curvature and (also denoted as ) is the surface tension. Although signs for these values vary, sign convention usually dictates positive curvature when convex and negative when concave.