Effect of Fluid-Structure Interaction on Sealed Flow Field and Leakage Rate Based on Computational Fluid Dynamics

This paper addresses the issue of reciprocating compressors staggered labyrinth seal structure. The internal flow field of sealed structure, the displacement of cylinder and piston for different tooth profile angles are analyzed synchronously using FLUENT software, and the effects of fluid-structure interaction on the performance of the labyrinth seal are revealed. The results indicate that with the growth of tooth profile angle, the leakage rate of labyrinth seal tends to decrease first, and then increase. The results of fluid-structure interaction analysis are close to those of actual engineering. The effect of fluid-structure interaction makes tiny deformation in calculation mesh of piston and cylinder structure, and the coupling interaction affects the performance of the labyrinth seal.

Leakage and Stiffness Characteristics of Bionic Cluster Spiral Groove Dry Gas Seal

Spiral groove dry gas seal(S?DGS), the most widely used DGS in the world, encounters the problem of high leakage rate and inferior film stability when used in high?speed machinery equipment, which could not be well solved by optimization of geometrical parameters and molded line of spiral groove. A new type of bionic cluster spiral groove DGS(CS?DGS) is proved to have superior film stability than S?DGS at the condition of high?speed and low?pressure numerically. A bionic CS?DGS is experimentally investigated and compared with common S?DGS in order to provide evidence for theoretical study. The film thickness and leakage rate of both bionic spiral groove and common spiral groove DGS are measured and compared with each other and with theoretical values under different closing force at the condition of static pressure, high?speed and low?pressure, and the film stiffness and stiffness?leakage ratio of these two face seals are derived by the relationship between closing force and film thickness at the steady state. Experimental results agree well with the theory that the leakage and stiffness of bionic CS?DGS are superior to that of common S?DGS under the condition of high?speed and low?pressure, with the decreasing amplitude of 20% to 40% and the growth amplitude of 20%, respectively. The opening performance and stiffness characteristics of bionic CS?DGS are inferior to that of common S?DGS when rotation speed equals to 0 r/min. The proposed research provides a new method to measure the axis film stiffness of DGS, and validates the superior performance of bionic CS?DGS at the condition of high?speed and low?pressure experimentally.

Effect of hole arrangement patterns on the leakage and rotordynamic characteristics of the honeycomb seal

The honeycomb seal is a vital component to reduce the leakage flow and improvethe system stability for the turbomachines. In this work, a three-dimensional model is established for the interlaced hole honeycomb seal (IHHCS) and the non-interlaced hole honeycombseal (NIHHCS) to investigate its leakage and rotordynamic characteristics by adopting computational fluid dynamics (CFD). Results show that the hole arrangement patterns have littleimpact on the pressure drop and turbulence kinetic energy distribution for the seals, and theIHHCS possesses a slightly lower leakage flow rate than the NIHHCS. Moreover, the numericalresults also show that the NIHHCS possesses a better rotordynamic performance than theIHHCS at all investigated conditions. Both seals show a larger k and a lower Ceff with the increase of the positive preswirl ratios and rotational speeds, while the negative preswirl ratioswould reduce the k and improve the Ceff. The NIHHCS possesses a higher absolute value ofFt for all operating conditions, this could explain the distinction of Ceff for both seals atdifferent working conditions.

Sealing Performance of Pressure-Adaptive Seal

A pressure-adaptive seal is developed to meet the demands of quick assembling and disassembling for an individual protection equipment in aerospace.The analysis model,which reflects the main characteristics of the seal structure,is built based on the finite element method and the Roth’s theory of rubber seal,and verified by the prototype test.The influences of precompression ratio,hardness of the sealing ring rubber,and friction coefficient on the sealing performance are investigated by variable parameter method.Results show that the model can describe the essential characteristics of the pressure-adaptive seal structure,which has good follow-up to the cavity pressure to achieve the purpose of pressure self-adaptive.The leakage rate correlates negatively with the precompression ratio of the sealing ring and the hardness of the sealing ring material,while is positively related to the friction coefficient between the sealing ring and the sealing edge.The maximum contact stress on sealing surface has negative correlation with the precompression ratio of the sealing ring,and positive correlation with the hardness of the seal ring material.The damage risk of the sealing ring increases with the increases of the precompression ratio of sealing ring,hardness of sealing ring material,and friction coefficient.