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Behind the heat conduction: How does hydraulic diameter affect the calculation of internal flow?
In fluid dynamics, hydraulic diameter (DH) is a widely used term, especially when dealing with the flow of non-circular pipes and channels.This concept allows engineers and researchers to calculate many parameters related to flow in the same way as circular pipes.Hydraulic diameters are often used in flow analysis, especially when calculating various performance indicators of heat conduction or fluid flow.
The hydraulic diameter is defined as:
DH = 4A / P, where A is the cross-sectional area of the flow and P is the wetting perimeter.
In this formula, the ratio of the cross-sectional area of the fluid to the wetting perimeter can help us determine the characteristics of the flow.For example, in a circular pipe, the hydraulic diameter and the diameter of the pipe are equal, which makes the calculation relatively simple.However, this is not the case for more complex geometries such as water pipes in daily life or special passages in industrial equipment.
The hydraulic diameter is not only cited in flow analysis, but also plays an important role in the calculation of heat conduction.This means that hydraulic diameter is an important reference indicator whether in designing a pipeline system or analyzing its thermodynamic properties.By understanding hydraulic diameters, engineers can better design and optimize fluid systems.
The hydraulic diameter can be regarded as a function of the hydraulic radius (RH), defined as:
RH = A / P, and the hydraulic diameter is four times its value, which is why it is named Hydraulic” diameter".
In some cases, especially when the fluid flows in the pipe, turbulence occurs.This turbulence will result in secondary flow in non-circular pipes, affecting the flow efficiency and the effect of heat conduction.Understanding how to effectively calculate and apply hydraulic diameters is key to improving system performance in this case.
In more complex cases, such as using the channels of Tesla valves, the definition of hydraulic diameter becomes richer.In this case, another formula for hydraulic diameter is: DH = 4V / S, where V represents the total wetting volume of the channel and S is the total wetting surface area.This definition provides a comprehensive perspective on flow characteristics and can effectively solve the problems of non-uniform and non-circular cross-sections that occur in general channels.
For a fully filled pipe or pipe, its cross-section is convex polygonal, and the hydraulic diameter is actually equivalent to the diameter of the incised circle.
This means, use water
