Patent ID: 8025296

Claim:
A shaft sealing mechanism comprising: a leaf seal in an annular gap between a rotor and a stator, said leaf seal including stacked sheets separated from one another by a minute gap in a circumferential direction of the rotor, said sheets dividing the annular gap into a high pressure side region and a low pressure side region by virtue of outer peripheral side end parts of said sheets being fixed on a stator side of said annular gap and inner peripheral side end parts of said sheets being unattached at a surface of the rotor, whereby fluid can be prevented from flowing in an axial direction of the rotor through the annular gap; and a high pressure side plate on the high pressure side region of said sheets, and a low pressure side plate on the low pressure side region of said sheets, with an inner peripheral side end of said high pressure side plate being positioned nearer the rotor than is an inner peripheral side end of said low pressure side plate, and with a space being provided between said inner peripheral side end of said low pressure side plate and a surface of the rotor, said space communicating with the annular gap, such that, in a state in which assembly of the leaf seal is complete and said sheets are under gas pressure, an inner peripheral side end portion of each of said sheets always makes contact with an inner peripheral side end portion of an immediately adjacent one of said sheets, wherein said sheets are arranged so as to satisfy ( R 2 ) 2 =( R 1 ) 2 +L 2 −2 ×R 1 ×L ×cos(α+90°), ( R 1 ) 2 =( R 2 ) 2 +L 2 −2 ×R 2 ×L ×cos(90°−β), n =(2×π× R 1 )/( t /sin α), t 0 =((2 ×π×R 2 )/ n )×sin β, and Δ t=t 0 −t, and wherein R 1 is an inner diameter of the annular gap, R 2 is an outer diameter of the annular gap, L is an effective length of one of said sheets, α is an angle between a radially outward surface of an inner peripheral side end portion of said one of said sheets and a contact surface of an inner periphery of the annular gap with said one of said sheets, β is an angle between a radially outward surface of an outer peripheral side fixed portion of said one of said sheets and a contact surface of an outer periphery of the annular gap with said one of said sheets, n is the number of said sheets, t is a thickness of a leaf of said one of said sheets, t 0 is a thickness of a proximal end part of said one of said sheets, and Δt is an amount by which a thickness of said one of said sheets is reduced by etching.