Study On Sealing Characteristics And Structure Improvement Of Aluminum Alloy Honeycomb Seal

Honeycomb seal is a common non-contact rotary seal in turbo machinery,and its sealing dynamic characteristics affect the operating efficiency and stability of the rotor system.The traditional steel honeycomb seal is easy to collide with the rotor and generate sparks.Compared with the previous aluminum alloy honeycomb seal,with its excellent performance,it has become an ideal material for honeycomb seal and has certain development prospects.In this thesis,by combining theory,simulation and experiment,the sealing characteristics of conventional aluminum alloy honeycomb seal and aluminum alloy honeycomb seal under impact conditions are deeply studied.The basic theory of sealing computational fluid dynamics,leakage formula and collision stiffness formula are analyzed theoretically,and the local fluid domain and solid domain model of honeycomb seal are established.The change of the leakage quantity of honeycomb seal under different accelerations is calculated,the honeycomb seal model impact test is carried out,and the simulation model is compared.The finite element model with the reverse spin structure is established,and the leakage quantity change rule is obtained by numerical calculation.The results show that when the hole depth reaches half of the honeycomb sealing opposite edge distance,the air flow backwash can form local low speed in the sealing gap area,and the sealing effect is good.At the same time,with the increase of hole depth,the vortex effect is the most fully developed.The vortex almost covers the whole honeycomb cavity,but the extrusion effect on the air flow in the gap is reduced.As the hole depth continued to increase,the vortex stabilized at the bottom and middle of the honeycomb hole,and the leakage tended to be stable.High and low peak structure can not significantly improve the sealing property of honeycomb seal,so the equal deep honeycomb seal is more in line with the actual requirements of production.With the increase of rotational speed,the effect of circumferential air flow increases,while the effect of axial air flow decreases correspondingly,and the leakage decreases.The greater the friction coefficient in the cavity,the greater the hindering effect on the vortex in the honeycomb,resulting in the decrease of the hindering effect of the vortex on the interstitial high-speed gas,and the gradual increase of the leakage of the honeycomb seal.At the moment of rotor collision,the leakage amount increases substantially,mainly because a large amount of air is squeezed into the honeycomb hole by the rotor at the moment of collision,which destroys the dissipation effect of the vortex in the honeycomb on the air flow in the gap.Then the air flow in the cavity becomes stable gradually,and the leakage amount decreases substantially until stable.With the increase of the number of collisions,the growth rate of leakage at the moment of collision increases gradually.The residual deformation of honeycomb seal in the collision interval leads to a small increase in leakage.With the increase of collision times,the leakage increases more.Honeycomb seal with reverse spin structure can form circumferential air flow at both ends of the reverse spin structure and the direction is opposite,easy to form convection in the gap,not only can weaken the circumferential air flow of the ring seal,improve the stability of the rotor,but also has a certain dissipation effect on the axial movement of the air flow.At the same time,the research also shows that the honeycomb seal with smaller Angle and more inverse-spin structure is more likely to form vortices,increase the turbulent dissipation rate,and have better sealing effect.