Large-diameter triple-eccentric metal hard-seal butterfly valves are widely used in petroleum, chemical, metallurgy, electric power and other industrial fields. They have compact structure, excellent sealing performance, high temperature and high pressure resistance and strong corrosion resistance. They show unique advantages especially in large-diameter applications. However, as the diameter of the valve increases, the force exerted by the fluid on the valve increases sharply, and the vibration problem caused by fluid-structure coupling becomes more obvious. This vibration not only affects the working stability of the valve, but may also cause structural fatigue damage and shorten the service life. CHNLGVF丨中國大乾閥門 has studied the fluid-solid coupling vibration characteristics of large-diameter triple-eccentric metal hard-seal butterfly valves in response to these problems, and proposed a structural optimization strategy to provide theoretical basis and practical guidance for the development and manufacturing of high-quality butterfly valves.

Compared with traditional butterfly valves, triple-eccentric butterfly valves have a three-dimensional eccentric design, including the axial eccentricity and radial eccentricity of the valve shaft relative to the center of the valve seat, as well as the geometric eccentricity of the valve seat cone surface and the butterfly plate. This design allows the contact between the butterfly plate and the valve seat to be completed only in a very small area during the opening and closing process of the valve, thereby reducing friction and wear and extending the service life of the valve.

The working principle of the triple eccentric butterfly valve mainly relies on the effect of three-dimensional geometric eccentricity. When the valve opens, the butterfly plate quickly separates from the valve seat, reducing frictional resistance; during the closing process, the butterfly plate gradually contacts the tapered valve seat, creating a uniform sealing force. The triple eccentric design effectively improves the sealing performance and working efficiency of the butterfly valve, especially maintaining a stable sealing effect under high temperature and high pressure.

Large-diameter butterfly valves have great advantages in the process of fluid transportation and control, but as the diameter increases, the force exerted by fluid power on the valve increases significantly. These forces include impact force, rotational torque and vibration, which pose severe challenges to the structural stability, sealing and service life of the butterfly valve. Therefore, how to optimize the structural design of butterfly valves under large-diameter conditions and reduce vibration caused by fluid-solid coupling is an urgent problem to be solved.

The flow field characteristics of large-diameter triple-eccentric butterfly valve are an important basis for studying its fluid-structure coupling vibration. At high flow rates, the vortices, turbulence and local pressure changes generated when the fluid passes through the valve will produce impact forces and induced vibrations on the valve body and valve plate. Flow field characteristics mainly include:

Fluid velocity distribution: The velocity field of the fluid passing through the valve is uneven, especially near the butterfly plate, which generates strong vortices and pressure gradients, which will produce unstable forces on the valve.

Pressure distribution and pressure difference: There is a large pressure difference between the inlet and outlet of large-diameter valves. Especially during the local opening and closing process, the local flow field pressure changes drastically, causing the valve plate to be subject to large pressure fluctuations, causing vibration.

CFD (Computational Fluid Dynamics) technology can accurately simulate the flow field characteristics of large-diameter triple-eccentric butterfly valves under different working conditions, and analyze the flow field changes of the valve in open, closed and different opening states. These data provide important reference for subsequent vibration analysis.

Fluid-structure interaction (FSI) refers to the dynamic process of interaction between fluid and structure. In large-diameter butterfly valves, the impact of fluid on the valve plate and valve body will cause elastic deformation of the structure. The deformation of the structure in turn affects the flow state of the fluid. The two work together to form a vibration phenomenon. The main manifestations of fluid-structure coupling include the following aspects:

Turbulence-induced vibration: The turbulence formed when the fluid passes through the butterfly valve exerts an unstable pulsating force on the valve plate, causing the valve plate to vibrate periodically. This vibration can cause stress concentration in the structure and cause structural fatigue damage.

Pressure fluctuation and resonance: When the fluid flow frequency is close to the natural frequency of the valve body or valve plate, structural resonance will be induced. Resonance will amplify the vibration amplitude and may cause damage to the valve structure in severe cases.

Fluid excitation and self-excited vibration: At high flow rates, fluid excitation phenomena may occur in local areas of the valve, especially self-excited vibration caused by vortex shedding, which poses a challenge to the structural stability of the butterfly plate and valve body.

Under the action of high-pressure fluid, key parts of large-diameter triple-eccentric butterfly valves such as the butterfly plate, valve seat and valve body will bear complex mechanical stress. These stresses mainly include shear stress, compressive stress caused by hydrodynamic pressure, and stress concentration caused by the structure's own weight. Stress concentration may cause local plastic deformation, especially during long-term use, fatigue damage will be more obvious.

Finite element analysis (FEA) can accurately simulate the stress distribution and deformation of the valve structure. By analyzing the stress distribution under different working conditions, we can find the stress concentration area, and reduce the impact of stress concentration on the valve life through structural optimization and material selection.

Resonance is one of the key issues in butterfly valve vibration. When the natural frequency of the valve is close to the fluid excitation frequency, resonance may occur in the structure. Resonance can significantly amplify the vibration amplitude, leading to fatigue damage of valve components or sealing failure. Therefore, in butterfly valve design, how to avoid resonance problems must be considered.

The natural frequency of the butterfly valve can be obtained through modal analysis, and combined with fluid dynamics analysis, the fluid-induced excitation frequency can be calculated. In order to avoid resonance, the structural parameters of the valve body and valve plate can be adjusted to make their natural frequencies far away from the fluid excitation frequency to avoid the occurrence of resonance.

To reduce the impact of fluid-structure coupling vibration on butterfly valve performance, optimizing the shape of the valve plate is one of the important strategies. The streamlined design of the valve plate can effectively reduce the impact of the fluid on the valve plate and reduce the generation of vortex and turbulence. In addition, increasing the rigidity and reasonable mass distribution of the valve plate can improve its anti-vibration performance.

The selection of materials has an important impact on the vibration characteristics of large-diameter triple-eccentric butterfly valves. CHNLGVF丨中國大乾閥門丨China Dagangyangmao introduces high-strength alloy materials to increase the rigidity of the valve body and valve plate, thereby improving their vibration resistance. At the same time, the use of new composite materials can reduce the weight of the valve and reduce the impact of fluid on the structure, thereby reducing the vibration amplitude.

To further reduce the vibration effects of butterfly valves, damping materials can be added inside the valve body or on the surface of the butterfly plate. These damping materials can effectively absorb vibration energy and reduce the transmission of vibration. At the same time, adding elastic supports or shock absorbers to key parts can also effectively alleviate vibration problems caused by fluid-structure coupling.

To improve the flow field characteristics of the large-diameter triple-eccentric butterfly valve, optimizing the design of the internal flow channel can reduce pressure fluctuation and turbulence formation of the fluid passing through the valve. For instance, a well-designed guide plate or guide hole can facilitate smooth fluid passage, diminish local eddy currents and flow separation, thus lowering vibration risk.

The R&D and manufacturing of large-diameter triple-eccentric butterfly valves require high-precision processing technology. CHNLGVF has introduced advanced manufacturing technologies such as CNC machining and 3D printing to ensure the processing accuracy of key parts of the valve. Especially during the processing of the valve plate and valve seat, high-precision CNC machine tools are used to ensure their surface roughness and geometric accuracy, and to ensure good coordination of the sealing surfaces.

In order to verify the vibration characteristics and structural stability of the butterfly valve, CHNLGVF conducted rigorous testing and experimental verification. This includes flow field testing, modal analysis, stress and strain testing, etc. in the laboratory to simulate the working status of the valve under different working conditions. Through these tests, not only can the rationality of the valve design be verified, but also data support can be provided for subsequent optimization.

In the research and development of large-diameter triple-eccentric metal hard-seal butterfly valves, CHNLGVF丨中國大乾閥門 adopted advanced fluid dynamics analysis and structural optimization strategies to address the problem of fluid-solid coupling vibration. By optimizing valve plate design, material selection and flow Field control significantly improves the anti-vibration performance and service life of the valve. In the future, with the continuous advancement of intelligent manufacturing and material science, the performance and reliability of butterfly valves will be further improved, promoting the widespread application of butterfly valve technology in various major industrial fields.