What is the pressure drop in butterfly valve fluid dynamics

The pressure drop in the fluid dynamics effect of a butterfly valve refers to the pressure loss caused by the valve structure and movement when the fluid passes through the butterfly valve. Pressure drop is a key parameter in butterfly valve performance evaluation, which directly affects the fluid dynamics characteristics, energy consumption and work efficiency of the system.

Butterfly valve pressure drop source

Disk resistance:

The existence of the butterfly plate will cause resistance to the fluid, resulting in the loss of fluid speed and kinetic energy. The shape of the butterfly plate, surface smoothness and sealing with the valve seat will all affect this resistance.

Change in cross-sectional area through which fluid passes:

As the butterfly valve opens and closes, the effective cross-sectional area through which the fluid passes changes. When the valve closes, the cross-sectional area decreases and the fluid velocity increases, causing a pressure rise. On the contrary, when the valve opens, the cross-sectional area increases and the fluid velocity decreases, causing a pressure drop.

Fluid Turbulence and Friction:

Inside a butterfly valve, fluids may enter turbulent conditions due to rapidly changing cross-sectional areas and flow rates. Friction caused by turbulence causes additional energy loss and increases pressure drop.

Factors affecting pressure drop

Valve opening:

The opening of the butterfly valve directly affects the cross-sectional area through which the fluid passes and the resistance caused by the valve. Typically, the more open the valve is, the smaller the pressure drop across the fluid, but this is weighed against the need for precise control of the fluid.

Fluid velocity:

Fluids flowing at high speeds usually increase the resistance and pressure drop caused by the valve. Therefore, the impact of fluid velocity on performance needs to be considered when designing butterfly valves to reduce pressure drop.

Butterfly plate design:

The shape, material and surface smoothness of the butterfly plate directly affect the resistance and pressure drop. The aerodynamically optimized disc design reduces drag and therefore pressure drop.

Properties of fluids:

Properties such as density and viscosity of the fluid also affect pressure drop. High-density, high-viscosity fluids generally cause larger pressure drops.

Calculation and evaluation of pressure drop

Fluid Dynamics Simulation:

Computational fluid dynamics (CFD) simulation is a common method to predict pressure drop by numerically simulating the behavior of the fluid inside a butterfly valve. This approach provides a more detailed understanding of the distribution of pressure drop.

Empirical formula:

Some empirical formulas and standards (such as fluid mechanics handbooks and valve standards) provide methods for estimating pressure drop based on butterfly valve parameters and operating conditions. These formulas are usually based on experimental data and theoretical analysis.

Ways to Reduce Pressure Drop

Optimize butterfly plate design:

The aerodynamically optimized butterfly plate shape is adopted to reduce resistance and reduce pressure drop.

Fluid Dynamics Optimization:

Through fluid mechanics simulation and other methods, the internal structure of the butterfly valve is optimized to reduce resistance and pressure drop.

Choose the appropriate fluid:

In specific applications, select appropriate fluid properties, such as low viscosity and low density fluids, to reduce pressure drop.