The concept of compressible flow and blockage (choking) in mechanical seal applications-

The concept of compressible flow and blockage (choking) in mechanical seal applications

　2017-03-07　　

The concept of compressible flow and blockage (choking) in mechanical seal applications

In the application of mechanical seals, compressible flow and blockage occur in the following way: that is, the static pressure drop is used to overcome the flow friction. This pressure drop will increase the specific volume of the gas. In order to maintain the same mass, the average velocity on each section increases with the increase in specific volume. As the friction speed increases, the momentum change of the fluid becomes more important. Because in order to accelerate the fluid to a greater speed, additional force is required, which is achieved through pressure drop, which results in a greater increase in specific volume. This process continues until the gas at the outlet end of the leakage channel reaches the maximum blocking condition, that is, when the flow velocity at the outlet is the speed of sound (Mach number is 1), the blockage occurs. At this time, when the flow reaches the maximum value, the flow in the tube no longer changes with the outlet conditions, and the flow parameters remain at the critical state value, even if the back pressure is reduced, it will not increase again. This phenomenon is called blocking (congestion) phenomenon. 　　331.html,

Mechanical seal application has the differential pressure flow of the rotating flow 　　 about the blockage of the mechanical seal