Patent ID: 8690523

Claim:
A fluid flow machine, comprising: a hub; a casing; a main flow path which is confined by the hub and casing; at least one row of blades arranged in the main flow path; a blade tip provided on the blade row, with the blade tip and the main flow path confinement performing a rotary movement relative to each other in a vicinity of the blade tip; a peripheral guiding device connected to the main flow path confinement and extending into the main flow path, the peripheral guiding device including a row of profiles extending from the main flow path confinement into the main flow path; a running gap positioned between the blade tip and the peripheral guiding device, with at least a portion of the running gap being retracted from the main flow path confinement; wherein a running gap retraction depth at a leading edge of the blade tip, t V , is larger than a running gap retraction depth at a trailing edge of the blade tip, t H , and that the running gap, at least in a partial section, is inclined against the main flow path confinement and against the meridional flow; wherein the running gap retraction depth continuously decreases from a forward gap endpoint of the peripheral guiding device to zero up to a point upstream of the trailing edge and within a bladed area of the blade row, and the peripheral guiding device has a wedge-type shape in meridional section; wherein a configuration of the peripheral guiding device and of the running gap, as referred to a meridional section of the fluid flow machine, is defined by the following characteristics: a) I VH is a length between the leading edge and the trailing edge at the blade tip, b) the running gap retraction depth from the main flow path confinement at the leading edge, t V , is subject to a requirement t V <0.3·I VH , c) the running gap retraction depth from the main flow path confinement at the trailing edge, t H , is subject to a requirement t H <0.3·I VH , d) a leading edge offset at the running gap between the blade tip and the peripheral guiding device at the running gap, d VM , is subject to: −0.05·I VH <d VM <0.5·I VH , e) a trailing edge offset at the running gap between the blade tip and the peripheral guiding device at the running gap, d HN , is subject to: −0.1·I VH <d HN <0.1·I VH , f) an upstream extension of the peripheral guiding device with respect to the leading edge of the blade tip, v, is subject to a requirement 0.05·I VH <v<I VH , g) a downstream extension of the peripheral guiding device with respect to the leading edge of the blade tip, w, is subject to a requirement 0<w<1.1 I VH .