词条 | Hydraulic diameter | ||||||||||||||||
释义 |
The hydraulic diameter, {{math|DH}}, is a commonly used term when handling flow in non-circular tubes and channels. Using this term, one can calculate many things in the same way as for a round tube. It is defined as[1][2] where {{mvar|A}} is the cross-sectional area of the flow, {{mvar|P}} is the wetted perimeter of the cross-section. More intuitively, the hydraulic diameter can be understood as a function of the hydraulic radius {{math|RH}}, which is defined as the cross-sectional area of the channel divided by the wetted perimeter. Here, the wetted perimeter includes all surfaces acted upon by shear stress from the fluid.[3] Note that for the case of a circular pipe, The need for the hydraulic diameter arises due to the use of a single dimension in case of dimensionless quantity such as Reynolds number, which prefer a single variable for flow analysis rather than the set of variables as listed in the table. The Manning formula contains a quantity called the hydraulic radius. Despite what the name may suggest, the hydraulic diameter is not twice the hydraulic radius, but four times larger. Hydraulic diameter is mainly used for calculations involving turbulent flow. Secondary flows can be observed in non-circular ducts as a result of turbulent shear stress in the turbulent flow. Hydraulic diameter is also used in calculation of heat transfer in internal-flow problems. List of hydraulic diameters
For a fully filled duct or pipe whose cross-section is a regular polygon, the hydraulic diameter is equivalent to the diameter of a circle inscribed within the wetted perimeter.{{cn|date=October 2017}} References1. ^{{Cite web|url=http://fluid.itcmp.pwr.wroc.pl/~znmp/dydaktyka/fundam_FM/Lecture13.pdf|title=Viscous flow in pipe|last=Kudela|first=Henryk|date=May 2017|website=|archive-url=|archive-date=|dead-url=|page=3|access-date=}} 2. ^{{Cite web|url=http://www.me.umn.edu/courses/me5341/handouts/essay%209.pdf|title=Hydraulic Diameter for Non-Circular Ducts|last=|first=|date=May 2017|website=|page=2|archive-url=|archive-date=|dead-url=|access-date=}} 3. ^Frank M. White. Fluid Mechanics. Seventh Ed. See also
4 : Fluid dynamics|Heat transfer|Hydrology|Hydraulics |
||||||||||||||||
随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识,基本涵盖了大多数领域的百科知识,是一部内容自由、开放的电子版国际百科全书。