Based on early studies

a straight-through labyrinth seal was developed

which has a bush with a rub-groove machined opposite the teeth cavity.The rub-groove manufactured on the smooth bush opposite to the tooth cavity destroys the continuity of the wall jet boundary layer

which lead to the jet flow change it direction and greatly improve sealing effect.The experimental studies show that it has a better sealing effect.The leakage coefficient of labyrinth seal with the rectangle rub-grooves is decreased 15% and the parallelogram rub-grooves 30%.Little windward angle of rub-grooves leads to jet deflection and big leeward angle of rub-grooves is beneficial to increase the resistance of the jet and also leads to jet deflection.