Optimization design for mechanical seals in reactor coolant pumps based on a fluid–solid strong-interaction model

Abstract

The study on the mechanism and performance of the mechanical seals in reactor coolant pumps (RCPs) is very important for the safe operations of pressurized water reactor power plants. By exploring the operating mechanism of the first seal of the hydrostatic mechanical seal in RCPs, an analytical fluid–solid strong-interaction model of the seal is proposed in this article. The model holds that the mechanical deformations of the seal assembly are dominated by the deflections of the seal rings, and this idea is demonstrated by the numerical simulation result of a fluid–solid interaction (FSI) model. Using the analytical FSI model, the regularity that the leakage rate of the first seal varies with the differential pressure in a RCP is obtained, and compared with the operational data, which is used to verify the model. Based on the understanding of the reliability of the seal, a dimensionless parameter Λ that acts as an attribute to the reliability is proposed in this article. Using the analytical FSI model and Λ as the optimization algorithm and optimization object, respectively, the optimum designs about the seal faceplateconfigurations are performed. Also, the specific optimization conclusions are given simultaneously.

Contact status between seal ring and its support: crucial factor in hydrostatic mechanical face seal

“…In the previous studies (Galenne and Pierre-Danos, 2007; Huang et al , 2014; Liao et al , 2011a, 2011b), the leakage rate only increases with increasing inlet pressure p o ; those models did not obtain the leakage rate steady period, considering the experiment results. As shown in Figure 7, a comparison of the TFSI model with the pure fluid, in which the effects of faceplate deflection are neglected, shows that composite deflections of the two rings gradually convert from convergence to divergence.…”

“…They found that the thermoelastic deformation value was of the same order of magnitude as the fluid film’s thickness, and thus, the TEHD behavior strongly affected the overall seal performance. Liao et al (2011a, 2011b) proposed an analytical fluid–solid strong-interaction model of the hydrostatic mechanical seal used in RCPs that was used to study the effects of the screw parameters and the geometric parameters of the seal faceplates on the sealing performance. Galenne and Pierre-Danos (2007) established a steady-state TEHD model using the influence coefficient method, which is an off-line calculation process.…”

Liquid spring damper for vertical landing Reusable Launch Vehicle under impact conditions

“…where K r is the spring rate which determines the restoring part of the force, a r represents the increase of the force that occurs during the sticking response mode, C r is the damping coefficient during the sticking mode used to prevent non-physical oscillations, b strib is a positive constant which represents the rate of the dynamic friction force variation with the relative velocity v p . In addition, the friction force between the cylinder and seal is related to the chamber pressures [33]. In this work, K r is assumed to change linearly with the reference chamber pressure following the relationship…”

“…The Reset Integral Friction Model [31] with the Stribeck effect is used in modified form here to model the contact friction between the footpad and ground. The contact tangential friction force t F between the footpad and ground uses equation (33) with the new state variable s rf . Additionally, the spring rate parameter in this case is defined as…”

Reliability evaluation of a dynamic pressure mechanical seal based on liquid film vaporization phase transition

“…In a connected study, Hao et al (2011) analyzed the failure of the mechanical seal of centrifugal pump by using the fuzzy comprehensive evaluation method, and proved that the method can be used to judge the reliability of the mechanical seal according to the risk matrix. Liao et al (2011) defined the reliability parameter Λ according to the film stiffness, minimum film thickness and contact force, and optimized the design parameters of mechanical seals based on this. Chen et al (2021) took the friction torque and leakage rate were used as the performance indexes of seal degradation process, based on the binary correlation analysis method, established the reliability evaluation model of the mechanical seal, and verified that the model has good performance through the degradation experiment.…”