초록 ▼

A transonic blade is provided that operates in a flow field where flow has a transonic speed or higher in an axial-flow rotating machine and that concurrently achieves a reduction in shock loss and in the local stress of the blade. The transonic blade includes a hub cross-sectional surface joined to

A transonic blade is provided that operates in a flow field where flow has a transonic speed or higher in an axial-flow rotating machine and that concurrently achieves a reduction in shock loss and in the local stress of the blade. The transonic blade includes a hub cross-sectional surface joined to a rotating shaft or an outer circumferential side casing of a rotating machine; a tip cross-sectional surface located furthest from the hub cross-sectional surface in a spanwise direction which is a vertical direction of the rotating shaft; a leading edge located on an upstream side; and a trailing edge located on a downstream side. At least a part of a passing working fluid flow has a transonic speed or higher. A portion of a stacking line which is a line connecting together respective gravity centers of cross-sectional surfaces located from the hub cross-sectional surface to the tip cross-sectional surface is located on a downstream side of a stacking center in a flow direction of a working fluid main flow.

대표청구항 ▼

1. A transonic blade comprising: a hub cross-sectional surface joined to a rotating shaft or an outer circumferential side casing of a rotating machine;a tip cross-sectional surface located furthest from the hub cross-sectional surface in a spanwise direction which is a vertical direction of the rot

1. A transonic blade comprising: a hub cross-sectional surface joined to a rotating shaft or an outer circumferential side casing of a rotating machine;a tip cross-sectional surface located furthest from the hub cross-sectional surface in a spanwise direction which is a vertical direction of the rotating shaft;a leading edge located on an upstream side in a flow direction of a working fluid main flow; and a trailing edge located on a downstream side in the flow direction of the working fluid main flow;wherein at least a part of a passing working fluid flow has a transonic speed or higher,wherein a portion of a stacking line which is a line connecting together respective gravity centers of cross-sectional surfaces located from the hub cross-sectional surface to the tip cross-sectional surface is located on a downstream side of a stacking center which corresponds to a gravity center position of the hub cross-sectional surface in the flow direction of the working fluid main flow,further comprising a third cross-sectional surface between the hub cross-sectional surface and the tip cross-sectional surface,wherein the stacking line protrudes toward the downstream side of the main flow direction between the third cross-sectional surface and the tip cross-sectional surface,the stacking line protrudes toward the upstream side in the main flow direction between the third cross-sectional surface and the hub cross-sectional surface,a gravity center position of the tip cross-sectional surface is located on the upstream side of the stacking center in the flow direction of the working fluid main flow, anda gravity center of the overall transonic blade is located on the downstream side of the stacking center. 2. The transonic blade according to claim 1, wherein a difference ε in a lengthwise direction of the rotating shaft between the gravity center of an overall transonic blade and the stacking center is set not to exceed a strength limit of the leading edge of the hub cross-sectional surface. 3. The transonic blade according to claim 2, wherein the ε is 1% or less of span. 4. The transonic blade according to claim 3, wherein the ε is generally equal to 0. 5. The transonic blade according to claim 1, wherein a gravity center of the transonic blade between the third cross-sectional surface and the tip cross-sectional surface is located on the main flow-directional downstream side of the stacking center. 6. The transonic blade according to claim 1, wherein a position corresponding to a largest amount of shifting of the stacking line toward the upstream side lies between the third cross-sectional surface and the hub cross-sectional surface. 7. The transonic blade according to claim 1, wherein the third cross-sectional surface is a mean cross-sectional surface. 8. The transonic blade according to claim 1, wherein respective positions of maximum thicknesses relative each to chord length are aligned with one another in airfoils located from the tip cross-sectional surface to the hub cross-sectional surface. 9. A compressor including a rotating shaft, a casing, a plurality of rotor blades, and a plurality of stationary blades, at least a part of a passing working fluid flow having a transonic speed or higher, wherein a rotor blade of the plurality of rotor blades on the most upstream side in a main flow direction comprises:a hub cross-sectional surface joined to the rotating shaft;a tip cross-sectional surface located furthest from the hub cross-sectional surface in a spanwise direction which is a vertical direction of the rotating shaft;a leading edge located on an upstream side in a flow direction of a working fluid main flow; anda trailing edge located on a downstream side in the flow direction of the working fluid main flow;wherein a difference ε in a lengthwise direction of the rotating shaft between the gravity center of an overall transonic blade and a stacking center which corresponds to a gravity center position of the hub cross-sectional surface is set not to exceed a strength limit of the leading edge of the hub cross-sectional surface,wherein a portion of a stacking line which is a line connecting together respective gravity centers of cross-sectional surfaces located from the hub cross-sectional surface to the tip cross-sectional surface is located on the downstream side of the stacking center in the flow direction of the working fluid main flow,the blade further comprising a third cross-sectional surface between the hub cross-sectional surface and the tip cross-sectional surface,wherein the stacking line protrudes toward the downstream side of the main flow direction between the third cross-sectional surface and the tip cross-sectional surface,the stacking line protrudes toward the upstream side in the main flow direction between the third cross-sectional surface and the hub cross-sectional surface,a gravity center position of the tip cross-sectional surface is located on the upstream side of the stacking center in the flow direction of the working fluid main flow, anda gravity center of the overall transonic blade is located on the downstream side of the stacking center. 10. A method of designing a transonic blade, the transonic blade including a hub cross-sectional surface joined to a rotating shaft or an outer circumferential side casing of a rotating machine; a tip cross-sectional surface located furthest from the hub cross-sectional surface in a spanwise direction which is a vertical direction of the rotating shaft; a third cross-sectional surface between the hub cross-sectional surface and the tip cross-sectional surface; a leading edge located on an upstream side in a flow direction of working fluid; and a trailing edge located on a downstream side in the flow direction of working fluid; at least a part of a passing working fluid flow having a transonic speed or higher, the method comprising: locating a portion of a stacking line which is a line connecting together respective gravity centers of cross-sectional surfaces located from the hub cross-sectional surface to the tip cross-sectional surface, on a downstream side of a stacking center which corresponds to a gravity center position of the hub cross-sectional surface in the flow direction of working fluid,determining a difference ε in a lengthwise position of the rotating shaft between the gravity center of an overall transonic blade and the stacking center so as not to exceed a strength limit of the leading edge of the hub cross-sectional surface,making the stacking line protrude toward the downstream side of the main flow direction between the third cross-sectional surface and the tip cross-sectional surface,making the stacking line protrude toward the upstream side in the main flow direction between the third cross-sectional surface and the hub cross-sectional surface,locating a gravity center position of the tip cross-sectional surface on the upstream side of the stacking center in the flow direction of the working fluid main flow, andlocating a gravity center of the overall transonic blade on the downstream side of the stacking center.