Research On Bidirectional Self-pumping Mechanical Seals With Hydro-dynamic-static Interaction

The requirement of high parameterization and long-cycle operation of industrial equipment makes non-contact mechanical seals develop rapidly.The non-contact mechanical seals are divided into two types: unidirectional rotation mode and bidirectional rotation mode.The unidirectional rotation mechanical seals can only work in one way,the reverse rotation can not produce hydrodynamic pressure to separate the rotating ring and stationary ring,resulting in rapid wear and tear lead to seal premature failure.For the latter,the rotational direction of the main shaft is not limited,and especially good for the positive and negative the fluid mechanical seal with export unidirectional valve,which was prone to fall into a shutdown reverse.A new mechanical seal named bidirectional self-pumping mechanical seal with hydro-dynamic-static interaction was put forward.Compared with the existing bidirectional rotation mechanical seal,the bidirectional self-pumping mechanical seal with hydro-dynamic-static interaction has the advantages of good sealing performance,strong self-cleaning ability,self-lubricating ability and self-cooling ability,besides,it do not need the buffer fluid supply auxiliary system.The research object was bidirectional self-pumping fluid dynamic and static pressure mechanical seal,the collector ring grooves and L-shaped holes were arranged on stationary ring,the dynamic pressure grooves were distributed on the rotating ring.The flow field was numerically simulated with Fluent to research and compare the mechanical seal performance and self-cleaning performance of pumping-out and pumping-in.The stability of bidirectional self-pumping fluid dynamic and static pressure mechanical seal when suffering a small axial disturbance was studied,and the stability of the mechanical seal was verified experimentally.The main work and conclusions are:(1)Analyzing and comparing the mechanical seal performance of pumping-out and pumping-in under the conditions of the same structural parameters(the ratio of groove width ridge width δ,the ratio of groove length and dam length γ,number of groove Ng)and working parameters(pressure difference Δp,rotation speed n).The results show that the pumping-out has weaker dynamic pressure effect and higher leakage than pumping-in mechanical seal.Therefore,the pumping-in mechanical seal performance is better than the pumping-out.(2)By using the particle tracing technique of Fluent software DOM model,the self-cleaning ability of self-pumping fluid dynamic and static pressure mechanical seals was quantitatively analyzed by avoiding uncontrollable factors in experiments.The results show that the chip discharge rate of pumping-out is higher than that of pumping-in,both of them will increase with the increasing of axial channel diameter.Under certain structural parameters,the chip discharge rate of pumping-out and pumping-in are the largest at the speed of 5000 rpm.(3)The dynamic model of bidirectional self-pumping mechanical seal with hydro-dynamic-static interaction was established,the mechanical motion of the stationary ring after axial perturbation was studied,and the stability of the mechanical seal was discussed preliminarily.The results show that under the action of axial excitation,it can be restored to the equilibrium after the axial perturbation within 4s.(4)The stability of bidirectional self-pumping mechanical seal with hydro-dynamic-static interaction was verified by experimental study.The test results show that the opening force of mechanical seal increases first after the axial disturbance,then it recovered to 96% of the original value in 4s.The results show that the mechanical seal has good stability.