Questions about the axial displacement of liquid in single screw pump

The screw has a single-head thread, and any cross-section of it is a circle with a radius R. The center of the cross-section is on the spiral line and deviates from the axis of the screw by an eccentricity e. The number of heads formed by rotating around the axis and moving along the axial direction is Lobes.: The number of screw stator heads T1 is one more than the number of rotor heads T2, that is, T1=T2+1. Their ratio becomes the head ratio. Screw pumps can be divided into single heads (1: 2) and long (2: 3,3: 4) etc. The greater the number of heads, the greater the output torque of the screw pump and the lower the speed. On the contrary, the smaller the output torque, the higher the speed. The inner surface of the bushing has double threads, and its arbitrary cross-section is an oblong circle. Both ends are semicircles with a radius R (equal to the screw cross-section radius), and the middle is a straight line segment with a length of 4e. Any cross-section of the bushing is the same long circle, but they are offset from each other by an angle. After the screw is installed into the bushing, closed chambers are formed between the surface of the screw and the internal thread surface of the bushing. At the same time, any cross-section is also divided into two crescent-shaped working chambers (upper and lower) (as shown in Figure 1-3). When the screw rotates, the volume of the first working chamber close to the suction chamber gradually increases, forming a negative pressure, and the liquid is sucked into the working chamber under the action of the pressure difference. As the screw continues to rotate and the volume of the working chamber continues to increase to the maximum, the working chamber is closed and the liquid is pushed axially toward the extrusion chamber. At the same time, the upper and lower working chambers alternately suck and discharge liquid in cycles, so the liquid is continuously pushed axially from the suction chamber to the extrusion chamber. I hope Baidu search can help you.

Thank you for your reply: handshake, I also learned it through some paper materials.* . It is the flow of liquid in the stator. The spatial imagination is always unclear, so now I can only memorize it as a formula. :L

The explanation is very detailed. At the end, I found that it was "searched on Baidu". The moderator really paid attention! Like