dynamic viscosity
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This post was last edited by 955559 on 2018-8-28 at 15:14. Dynamic viscosity, also known as absolute viscosity or simply viscosity, is defined as the ratio of stress to strain rate. Numerically, it equals the internal friction force resulting from the interaction of the fluid between two parallel plates with an area of 1 m² and a separation of 1 m, when these plates move relative to each other at a speed of 1 m/s. The unit is N·s/m² (newtons-seconds per square meter), which is also Pa·s (pascals-second); its dimension is M/(L·T). What is the actual use of the dynamic viscosity parameter? Is it something to consider when choosing a flow meter? Or what?
Considerations are made when choosing a flow meter, and the same holds true when selecting a control valve. This is mainly because the annual viscosity affects the inner diameter of the opening, which in turn impacts the calculation of flow rate.
For a flow meter to function properly, the fluid must be in an appropriate flow state, which is determined by the fluid’s Reynolds number. Therefore, the flow meter can operate correctly only within a certain range of Reynolds numbers. One of the parameters required for calculating the Reynolds number is the fluid’s viscosity; hence, this property of the fluid is an important factor to consider when selecting a flow meter. Additionally, when control valves are used with fluids of high viscosity, it is necessary to adjust the calculated CV value; therefore, the viscosity parameter is also required. In terms of the process, the main task is to calculate the pressure loss in the piping system, and this calculation also requires the viscosity parameter.
It is used in calculating the Reynolds number, and the Reynolds number is the most important factor for differential pressure flow meters.