Numerical and experimental investigation on interstage pressure drop equalization of differential multi-stage brush seals

Through analysis of multi-stage brush seal interstage pressure drop distribution characteristic theory，a new brush seal structure of differential stage was presented，and based on the fluid-structure interaction method，a new multi-stage brush seal three-dimensional entity model at all stages was established to build a new multi-stage brush type seal leakage flow characteristics experiment device；through numerical and experimental research under the different working conditions，the effects of structural parameters on pressure drop equilibrium and leakage characteristics of a new type of multi-stage brush seal were analyzed.The results showed that the standard deviation of the equilibrium ratio of pressure drop between different stages of the traditional multi-stage brush seal structure was 8.41，and that of the equilibrium ratio of pressure drop between different stages of the new structure was 4.69 and 2.07.Compared with the traditional structure at each stage，the new differential multi-stage brush seal with the increasing area of the downstream stage can effectively improve the imbalance of pressure drop between stages.Increasing the backing plate protection height could bring about the minimum standard deviation of the equilibrium of pressure drop ratio between different stages of the new structure，and the pressure drop ratio between different stages was close to each other，which can significantly improve the equilibrium of pressure drop between different stages of the new structure.Reducing the thickness of the brush bundle and increasing the clearance between the brush bundle and the rotor surface could make the leakage of the new multi-stage brush seal increase obviously.