Magnetic Circuit Design and Finite Element Simulation Analysis of Magnetic Fluid Rotating Dynamic Sealing Device

The magnetic fluid rotary dynamic sealing device is based on the magnetic fluid material. The typical sealing structure is to fill the magnetic fluid in the gap between the shaft and the magnetic pole, and keep it in the sealing gap under the action of the external magnetic field to form a liquid "O"-shaped sealing ring to block it. The sealing effect of this kind of device largely depends on the design of the magnetic circuit structure of the device. In this paper, ANSYS finite element simulation is used to analyze the influence of seal stages, tooth shape and the number of permanent magnets on the magnetic fluid rotating dynamic seal. The L9 (34) factor level table is designed by orthogonal test method to analyze the priority of the influence of tooth width, seal clearance and chamfering on the magnetic fluid sealing performance, which provides the reference for the structural design and magnetic circuit design of magnetic fluid rotating dynamic seal.

Rotating Brush Seal Design and Performance Testing

Brush seals are widely used in various turbomachinery applications because they provide reduced leakage than labyrinth seals in a compact space. Brush seals are generally mounted on static components and their flexible bristle tips engage the rotor to form a dynamic seal. In this paper, development of a brush seal mounted on a rotor is discussed. Benefits of this enhancement to brush seal include avoiding localized rubs on the rotor, which reduces heating of a local spot and resulting rotor bow and instabilities. The bristles are angled circumferentially instead of axially and are supported by a conical backplate. Under rotation, the bristles are pushed towards the backplate by the centrifugal force. Seal configurations are designed to fit into interstage and inter-shaft locations. A modeling approach for predicting stiffness and operating stresses in these seals also is outlined. A test setup is developed to characterize the performance of rotating brush seals under engine-representative centrifugal force and pressure differentials. Presented results demonstrate that brush seal can achieve tight effective gaps and desired performance after undergoing initial wear.

Analytical Modeling and Design of Novel Conical Halbach Permanent Magnet Couplings for Underwater Propulsion

Permanent magnet couplings can convert a dynamic seal into a static seal, thereby greatly improving the stability of the underwater propulsion unit. In order to make full use of the tail space and improve the transmitted torque capability, a conical Halbach permanent magnet coupling (C-HPMC) is proposed in this paper. The C-HPMC combines multiple cylindrical HPMCs with different sizes into an approximately conical structure. Compared with the conical permanent magnet couplings in our previous work, the novel C-HPMC has better torque performance and is easy to process. The analytical calculation method of transmitted torque of C-HPMC is proposed on the basis of torque calculation of the three common types of HPMCs. The accuracy of the torque calculation of the three HPMCs is verified, and the torque performance of the three HPMCSs of different sizes is compared and discussed. The “optimal type selection” method is proposed and applied in the design of C-HPMC. Finally, on the basis of torque analysis calculation and axial force calculation, a complete flowchart of the design and performance analysis of C-HPMC is described.

Design and seal performance analysis of bionic sealing ring for dynamic seal

In this paper, the non-smooth surface technology is applied to the surface structure of the rectangular sealing ring, and a bionic sealing ring is designed. Two-dimensional axisymmetric models of rectangular and bionic sealing rings were established. Effects of pre-compression amount, fluid pressure, friction coefficient and reciprocating velocity on the static and dynamic sealing performance of two sealing rings were studied. The results show that the seal performance of the bionic sealing ring is greater than that of rectangular. The static seal performance increases with the increasing of fluid pressure and compression amount. Dynamic sealing performance in outward stroke is better than it in the inward stroke. Friction coefficient has a smaller effect on the bionic sealing ring’s sealing performance than rectangular sealing ring. Therefore, using the bionic sealing ring can improve the static and dynamic seal performances and prolong its service life in hydraulic systems, rotating machinery and reciprocating machinery.

Design of a Measuring Device and Winch Structure for Detecting the Distance and Direction of Two Seabed Pipelines

To measure the distance and direction between the flanges of two seabed pipelines, a measuring device for pulling a rope in seawater was designed. Addressing the sealing problem of the key equipment the rotating shaft of the rope winch, we used the magnetic coupling principle to transfer the driving moment, and converted the dynamic seal into a static seal structure to reliably seal the motor. Through an experiment measuring two pipelines with the underwater rope pulling device, we verified that the measuring accuracy of the device meets the design requirements, and confirmed the feasibility of applying magnetic coupling technology in winches.

Research on Device Used to Measure Distance and Position for Two Pipelines on the Seafloor

In order to solve the problem of measuring the distance and position between the flanges of two pipelines on the seabed, a measuring device for pulling rope in seawater was designed. Aiming at the sealing problem of the key equipment that is the rotating shaft of the rope winch, this paper used the principle of the magnetic coupling to transfer the driving moment, and adopted the method of converting the dynamic seal into the static seal structure to realize the reliable sealing of the motor. Through the experiment of measuring two pipelines with underwater rope pulling device, it was verified that the measuring accuracy of the device meets the design requirements, and the feasibility of the application of magnetic coupling technology in winch is also verified.