Method for designing a fluid flow engine and fluid flow engine

Abstract

A fluid flow engine, in particular compressor or turbine of a gas turbine engine, having a stationary engine casing and a rotor assembly rotatable supported in the engine casing, the rotor assembly having at least one circumferentially extending rotor blade row with a plurality of radially extending unshrouded rotor blades, an inner surface of the engine casing with at least one circumferentially extending slot arranged radially outside of the rotor blade row, wherein a gap is provided between tips of the rotor blades and a base of the slot, whereby the depth of the slot is less than the gap height of the gap.

1 . A method for designing a fluid flow engine, comprising:
 determining a minimum gap height (H) of a required gap between tips of a rotatable supported circumferential row of radially extending rotor blades and an inner surface of a stationary engine casing of a conventional fluid flow engine, wherein the gap is required to prevent radial contact between the tips and the inner surface as far as possible;   manufacturing an engine casing with at least one circumferentially extending slot at an inner surface of the engine casing, such that a depth (d) of said slot is less than the determined minimum gap height (H); and   manufacturing rotor blades for at least one circumferentially extending rotor blade row that can be arranged radially inside of said slot, such that a gap height (H 1 ) of a gap between the tips of the rotor blades and a base of said slot equals the determined minimum gap height.   
     
     
         2 . The method according to  claim 1 ,
 wherein the engine casing is manufactured such that the depth (d) of said slot lies within a range of 50% to 95% of the determined minimum gap height (H).   
     
     
         3 . The method according to  claim 1 ,
 wherein the engine casing is manufactured such that a cross section of said slot is rectangular-shaped.   
     
     
         4 . A fluid flow engine, comprising:
 a stationary engine casing and a rotor assembly rotatable supported in the engine casing,   the rotor assembly comprising at least one circumferentially extending rotor blade row with a plurality of radially extending unshrouded rotor blades,   an inner surface of the engine casing comprising at least one circumferentially extending slot arranged radially outside of the rotor blade row,   wherein a gap is provided between tips of the rotor blades and a base of said slot, and   wherein a depth (d) of said slot is less than the gap height (H 1 ) of the gap.   
     
     
         5 . The fluid flow engine according to  claim 4 ,
 wherein the depth (d) of said slot lies within a range of 50% to 95% of the gap height (H 1 ) of the gap.   
     
     
         6 . The fluid flow engine according to  claim 4 ,
 wherein a cross section of said slot is rectangular-shaped.   
     
     
         7 . The method according to  claim 1 ,
 wherein the fluid flow engine comprises a compressor or a turbine of a gas turbine engine.   
     
     
         8 . The fluid flow engine according to  claim 4 ,
 wherein the fluid flow engine comprises a compressor or a turbine of a gas turbine engine.