Cyclone velocity decomposition
Release time: 2015/10/26 Ai Yi NewsViews : 1337
Cyclone is an important part of desilter, sand remover and mud cleaner.
The velocity at any point in the cyclone can be decomposed into three partial velocities, namely tangential velocity, radial velocity, and axial velocity.
Below the horizontal swirling surface below the lower edge of the overflow pipe, the static pressure head decreases from the periphery to the center, and the degree of reduction depends on the swirling speed. Since the sum of the static pressure head and the speed head is equal on any half of the cyclone, when the static pressure head decreases with decreasing radius, the speed head will inevitably increase, so the closer it is to the center, the greater the circumferential speed. The circumferential velocity of the fluid near the centerline of the cyclone and the corresponding centrifugal force become larger, so that the liquid ruptures and forms an air-like air core along the centerline.
The relationship between the tangential partial velocity and the radius of the hydrocyclone is: the tangential partial velocity increases as the rotation radius of the liquid decreases, but reaches a maximum near the radius of the overflow pipe (that is, near the air column), and then decreases sharply small.
Axial speed is also called vertical speed. In the hydrocyclone, the high-speed downward flow along the inner wall of the cylinder and the cone is very important for the cyclone to work, because it carries the separated particle bottom orifice.
The downward flow portion in the center region is balanced with the upward flow. That is to say, on any horizontal section along the height, there is always a point where the one-way velocity is zero, the inner velocity of the point is positive, and the outer axial velocity of the point is negative. The locus of the point where the axial velocity is zero inside the cyclone is a conical surface, and the liquid moves upwards within the surface, and the liquid flow moves downwards at its outer side.
So far, the research on radial velocity is not enough, and there are still differences on the distribution of radial velocity. However, the radial velocity is usually much smaller than the other two partial velocities, and it is difficult to determine it accurately, so it can be ignored in actual calculation. This velocity distribution in a hydrocyclone is limited to a qualitative description. Even the flow pattern of water with low density and viscosity is very complicated. Therefore, the flow pattern of the liquid in the cyclone will never be the same if the geometry is different or the viscosity of the liquid is different.