Maximum entrainment limit

Applications
One application of the Weber number is the study of heat pipes. When the momentum flux in the vapor core of the heat pipe is high, there is a possibility that the shear stress exerted on the liquid in the wick can be large enough to entrain droplets into the vapor flow. The Weber number is the dimensionless parameter that determines the onset of this phenomenon called the entrainment limit (Weber number greater than or equal to 1). In this case the Weber number is defined as the ratio of the momentum in the vapor layer divided by the surface tension force restraining the liquid, where the characteristic length is the surface pore size.

https://en.wikipedia.org/wiki/Weber_number

Aplicacions
Una aplicació del nombre de Weber és l'estudi dels tubs termosifons bifàsics (més coneguts pel seu nom en anglès heat pipe). Quan el flux de moment en el nucli de vapor del heat pipe és alt, hi ha la possibilitat que l'esforç tallant exercit en el líquid a la metxa pot ser prou gran com per crear gotes en el flux de vapor. El nombre de Weber és un paràmetre adimensional que determina l'inici d'un fenomen anomenat límit d'arrossegament (quan el nombre de Weber és igual o més gran que 1). En aquest cas el nombre de Weber és definit com la raó entre el moment en la capa de vapor entre el tensor de superfície refrenant el líquid, on la llargària característica és la mida del porus.

https://ca.wikipedia.org/wiki/Nombre_de_Weber

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Note added at 1 hr (2019-05-03 20:43:52 GMT)
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Verifying the Performance of a Cleanroom

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To verify that your cleanroom is operating according to design specifications, several tests can be run with the help of the Institute of Environmental Sciences Recommended Practice 006.

By William Whyte

In a conventionally ventilated room, if the air supply issues direct from HEPA filters in the ceiling, particles may be entrained from the room into the clean air supply. It is difficult at the perimeter of the filter to distinguish between a leak from the case/housing interface and entrainment of particles from the room. Use of a box a few inches deep, which is placed against the ceiling and round the filter, can prevent entrainment. If there is a problem with leaks coming from the filter case, then it is difficult to distinguish them from leaks between the filters case and the filter housing. It may be possible to resolve this by removing the filter and testing it on a rig.

https://electroiq.com/1996/06/verifying-the-performance-of-a...

Page 67
Rinse test. A test to determine cleanliness by entrainment or by solution of soluble materials with a suitable rinsing liquid; the liquid is sloshed or agitated over the critical surfaces of the component to ensure entrainment of particles.

http://www.oir.caltech.edu/twiki_oir/pub/Main/PatrickMurphy/...