ASSEMBLY FORMING A SEAL FOR A TURBOMACHINE INCLUDING A BRUSH SEAL AND AT LEAST ONE LIP
The main object of the invention is an assembly forming a seal ( 1 ) for a turbomachine ( 10 ), used to provide a seal between two elements of the turbomachine ( 10 ) rotating relative to one another, and being rotationally symmetrical around an axis (X) of the assembly forming a seal ( 1 ), characterised in that it includes a brush seal ( 2 ), which is annular around the axis (X) of the assembly forming a seal ( 1 ), having multiple elastic sealing bristles ( 5, 5 a, 5 b ) intended to be attached to one of the two elements of the turbomachine ( 10 ) rotating relative to one another, and at least one lip ( 3, 3 a, 3 b, 3 c ), which is annular around the axis (X) of the assembly forming a seal ( 1 ), extending radially in the direction of the brush seal ( 2 ), intended to be attached to the other of the two elements of the turbomachine ( 10 ) rotating relative to one another, where the said at least one lip ( 3, 3 a, 3 b, 3 c ) penetrates at least partially into the brush seal ( 2 ).
1 . An assembly forming a seal for a turbomachine, used to form a seal between two elements of the turbomachine rotating relative to one another, and being rotationally symmetrical around an axis of the assembly forming a seal, including:
a brush seal, which is annular around the axis of the assembly forming a seal, having multiple elastic sealing bristles, intended to be attached to one of the two elements of the turbomachine rotating relative to one another other,
at least one lip, which is annular around the axis of the assembly forming a seal, extending radially in the direction of the brush seal, intended to be attached to the other of the two elements of the turbomachine rotating relative to one another, where the said at least one lip penetrates at least partially into the brush seal,
and wherein the total radial length of the bristles of the brush seal is chosen to allow sufficient penetration of the said at least one lip into the brush seal, where this total radial length of the bristles of the brush seal satisfies the following relationship:
l P ≧d+dr max , where:
d is the radial distance between the top of the said at least one lip and the base of the bristles of the brush seal, and
dr max is the maximum relative radial displacement between the two elements of the turbomachine ( 10 ) rotating relative to one another.
2 . An assembly according to claim 1 , wherein the total axial thickness of the bristles of the brush seal is chosen to allow a constant penetration of the said at least one lip into the brush seal, where this total axial thickness of the bristles of the brush seal satisfies the following relationship:
e B ≧e L +2· dx max , where:
e L is the total axial thickness of the said at least one lip, and
dx max is the maximum relative axial displacement between the two elements of the turbomachine rotating relative to one another.
3 . An assembly according to claim 1 , wherein the radial distance between the top of the said at least one lip and the base of the bristles of the brush seal is chosen to allow a flexibility of the bristles enabling the axial movements to be absorbed, where this radial distance (d) satisfies the following relationship:
d>dr max +n·dx max , where:
dx max is the maximum relative axial displacement between the two elements of the turbomachine rotating relative to one another,
dr max is the maximum relative radial displacement between the two elements of the turbomachine rotating relative to one another, and
n is a factor which depends on the flexibility of the bristles used.
4 . An assembly according to claim 1 , wherein the radial distance between the free ends of the bristles of the brush seal and the base of the said at least one lip is chosen to allow a flexibility of the bristles enabling the radial movements to be absorbed, where this radial distance satisfies the following relationship:
j>dr max , where:
dr max is the maximum relative radial displacement between the two elements of the turbomachine ( 10 ) rotating relative to one another.
5 . An assembly according to claim 1 , wherein the said at least one lip penetrates at least partially into the brush seal, in an area of the brush seal having no elastic sealing bristles.
6 . An assembly according to claim 1 , wherein it includes multiple lips, which are annular around the axis of the assembly forming a seal, spaced axially and extending radially in the direction of the brush seal, where the multiple lips penetrate at least partially into the brush seal.
7 . An assembly according to claim 1 , wherein the friction surface for the assembly forming a seal corresponds to the contact of only a proportion of the bristles of the brush seal on the wall of the said at least one lip.
8 . An assembly according to claim 1 , wherein at least a proportion of the bristles of the brush seal is able to come into contact with the side wall of the said at least one lip.
9 . A turbomachine, wherein including an assembly forming a seal according to claim 1 .
10 . A turbomachine according to claim 9 , wherein it is of the unshrouded fan type, including a doublet of unshrouded counter-rotating fans.
11 . A turbomachine according to claim 9 , wherein it is of the high sealing radius type, including seals located at some distance from the axis of the turbomachine, and located at sealing radii of between 300 and 800 mm relative to the axis of the turbomachine.