Turbine blade tip seal

Claim 2

In a gas turbine engine which includes a turbine wheel comprising a disk and a plurality of blades radially extending from the disk, an outer case having a circumferential track at a radius greater than the radius of the wheel at the tips of the blades, and a gas seal comprising seal segments which are positioned with respect to the case track and which radially enclose the wheel to reduce gas leakage across the wheel between the case and the tips of the blades wherein the improvement comprises: an arcuate hook which extends from each seal segment and has a radius of curvature less than the track radius, the hook engaging the track along two lines of contact to position each seal segment with respect to the case track.

Claim 3

In a gas turbine engine which includes a turbine wheel comprising a disk and a plurality of blades radially extending from the disk, an outer case having a circumferential track at a radius greater than the radius of the wheel at the tips of blades, and a gas seal comprising seal segments which are positioned with respect to the case track and which radially enclose the wheel to reduce gas leakage across the wheel between the case and the tips of the blades wherein the improvement comprises: a sealing surface on each seal segment which has a surface radius of curvature during the cold engine condition which is less than the radius of the wheel at the blade tips and a surface radius of curvature at an operating condition which is substantially equal to the radius of the wheel at the blade tips; and an arcuate hook which extends from each seal segment and has a radius of curvature less than the track radius, the hook engaging the track along two lines of contact to position each seal segment with respect to the case track.

Claim 4

In a gas turbine engine which includes a turbine wheel comprising a disk and a plurality of blades radially extending from the disk, an outer case having a circumferential track at a radius greater than the radius of the wheel at the tips of blades, and a gas seal comprising seal segments which are positioned with respect to the case track and which radially enclose the wheel to reduce gas leakage across the wheel between the case and the tips of the blades wherein the improvement comprises: a sealing surface on each seal segment which has a surface radius of curvature during the cold engine condition which is less than the radius of the wheel at the blade tips and a surface radius of curvature at an operating condition which is substantially equal to the radius of the wheel at the blade tips; and an arcuate hook which extends from each seal segment and has a radius of curvature less than the track radius, the hook engaging the track along two lines of contact to position each seal segment with respect to the case track.

Claim 5

Apparatus for reducing gas leakage between the stages of a gas turbine engine, comprising: a turbine wheel having a plurality of turbine blades extending radially from the disk and having a wheel radius R-3 between the engine centerline and the tips of the blades; a turbine case which radially encloses the wheel and has a circumferential track with a radius R-4; and a blade tip seal which is circumferentially segmented and concentrically positioned about the wheel internal to the case and wherein each segment having a sealing edge on the downstream end comprises, an arcuate sealing surface having a radius of curvature in cold engine conditions which is less than the radius R-3 and a radius of curvature in normal operating conditions which is substantially equal to the radius R-3; and an arcuate hook having a radius of curvature R-2 which is less than the radius R-4 during all engine conditions, the arcuate hook engaging the circumferential trAck in the case.

Claim 6

Apparatus for reducing gas leakage between the stages of a gas turbine engine, comprising: a turbine wheel having a plurality of turbine blades extending radially from the disk and having a wheel radius R-3 between the engine centerline and the tips of the blades; a turbine case which radially encloses the wheel and has a circumferential track with a radius R-4; and a blade tip seal which is circumferentially segmented and concentrically positioned about the wheel internal to the case and wherein each segment having a sealing edge on the downstream end comprises, an arcuate sealing surface having a radius of curvature in cold engine conditions which is less than the radius R-3 and a radius of curvature in normal operating conditions which is substantially equal to the radius R-3; and an arcuate hook having a radius of curvature R-2 which is less than the radius R-4 during all engine conditions, the arcuate hook engaging the circumferential trAck in the case.

Claim 7

The invention according to claim 3 further including a plurality of turbine vanes located downstream from the blades, each vane having a platform section with an upstream edge which cooperates with the downstream edge of the adjacent seal segment during engine operation to reduce gas leakage in the radial direction between the seal and the vane.