Labyrinth Seal Flow Field Of Rotor Dynamics Coupling

Labyrinth seal is a kind of untouched dynamical seal which is commonly used in turbo-machinery to reduce the leakage loss. It is a well known problem that seals induce fluid forces on the rotor which can excite rotor vibrations and thereby destabilize the machine. So it is vital important to simulate the gas flow and pressure distribution inside labyrinth seal in order to deeply study the destabilization mechanism and the influence factors.The flow inside labyrinth seal obeys all the conservation equations of fluid flow for mass, momentum and energy. So the commercial CFD software Fluent was used to simulate and analysis the compressible gas flow inside the seal for the see-through labyrinth seal, then a fluid-rotor quasi-coupling method was raised between labyrinth seal flow and rotor dynamics. Finally, the dynamic characteristic of the multi-disks rotor system with labyrinth seal equipment which supported by sliding bearing was analyzed by this method. The total works in this paper are as follows:(1) The finite element model for the flow inside labyrinth seal was established, the effect of grid element length-width ratio to the iterate convergence was considered; mass flow rate under the condition of various different pressure ratio, tooth clearance and pre-swirl was calculated by Fluent, and the results were compared with the result calculated by theory formula method.(2) The influence of rotor velocity to the seal force was studied by Using moving reference frame technology, after obtained the seal force with various eccentrically rate and gas inlet pre-swirl, the calculation method for seal force at random position, random velocity was founded, then the couple analysis between fluid and rotor was achieved. The couple analysis result indicated that gas inlet pre-swirl has vital influence to the system stability, when the gas inlet with no pre-swirl, the influence was very small and the system was still a stability system, after given a 7 degree pre-swirl, the system stability got worsen, system lost stability.(3) A labyrinth seal equipment was Installed in the former rotor sliding bearing test-bed, part of gas excited vibration test was finished, because of the limited time and experiment condition, it lakes of good results.