Mechanical seal convergence gap fluid film model-

Fluid film model of convergent gap of mechanical seal

　2017-06-11　　

Mechanical seal convergence gap fluid film model:

As shown in Figure 2-46(a), the parallel plates move relative to each other, and the 368 mechanical seal is a pure shear flow according to Newton's law. : According to the theorem of continuity, the pressure of each broken curve along the length remains unchanged.

As shown in Figure 2-46(b), the two planes are slightly inclined to each other, and one of the planes moves relative to each other. Due to the different quotients at both ends of the gap. For a flat plate of equal width, according to the continuity theorem, the flow velocity changes along the length and gradually increases. This can determine the pressure change along the length of the gap.

As shown in Figure 2-46(c), it can be assumed that there is a load W acting on the upper plate, and the fluid flows out from both ends of the gap, and the flow velocity is parabolic, resulting in a differential pressure flow.

As shown in Figure 2-46(d), the actual velocity distribution and pressure distribution are obtained after the superposition of the shear flow and the differential pressure flow

It can be seen that the fluid film layer of the convergence gap has a certain bearing capacity and generates a dynamic pressure effect.

Assuming that the slab is infinitely wide and the viscosity and density are constants, formula (2-13b) can be used to determine the load-bearing capacity W

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