The influence of the positive and negative stiffness of mechanical seal fluid-

The influence of the positive and negative stiffness of mechanical seal fluid

　2017-06-11　　

The influence of the positive and negative stiffness of mechanical seal fluid:

When there is disturbance, if the thickness h of the fluid film becomes thinner and the average pressure of the fluid film increases, the fluid film has positive rigidity and the hydrostatic pressure seal (such as mechanical seal) works stably. Flashing means that the pressure of the fluid film increases, and the force of the fluid medium of the sealing ring does not change. Therefore, the pressure of the fluid film is greater than the pressure of the medium, and the sealing surface is restored to its original position to work, and the fluid film is thickened. This shows that the seal has positive stiffness. The positive stiffness seal produces a restoring force and has the ability to restore the fluid film to its original thickness. Seals such as grooved orifice type, radially convergent conical indium, and radially convergent step surface type have positive rigidity, and the fluid film between the sealing surfaces has sufficient anti-interference ability. Radial expansion cone type seals have negative stiffness. Rigidity. When the load increases, the thickness of the fluid film increases, which will cause the sealing surface to open and fail; when the load decreases, the thickness of the fluid film decreases, and the sealing surface will come into contact. Therefore, the sealing operation with negative stiffness is unstable.

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