A fluid flow machine, comprising:
- a main flow path that is formed by a hub and a housing,
- at least one arrangement of rotating blades arranged in the main flow path that supply energy to a working fluid and form a rotor assembly group,
- at least one arrangement of resting blades arranged in the main flow path adjacent to the rotor assembly group that form a stator assembly group, wherein
- respectively one rotor assembly group and one stator assembly group adjacent thereto form a stage of the fluid flow machine, and
- cross-sectional areas of the main flow path are submitted to a change in a downstream direction in at least one stage of the fluid flow machine, wherein
- in at least one stage, averaged blade profile angles βRI, βRE of the rotor assembly group, averaged blade profile angles βSI, βSE of the stator assembly group, as well as a course of the cross-sectional areas of the main flow path in the downstream direction are selected such that they satisfy the following relationship:
- ACC/RSC>−7.2143LC2+1.5414LC+2.776,
- wherein ACC indicates an area change count of a stage and is defined based on the following formula:
- ACC=[(R22−R12)/(R42−R32)]/[(R62−R52)/(R82−R72)],
- wherein, in a through-flow direction of the fluid flow machine, it applies that
- R1 is a radius at a radially innermost point of a leading edge of a blade row of the rotor assembly group that is located furthest upstream,
- R2 is a radius at a radially outermost point of the leading edge of the blade row of the rotor assembly group that is located furthest upstream,
- R3 is a radius at a radially innermost point of a trailing edge of a blade row of the rotor assembly group that is located furthest downstream,
- R4 is a radius at a radially outermost point of the trailing edge of the blade row of the rotor assembly group that is located furthest downstream,
- R5 is a radius at a radially innermost point of a leading edge of a blade row of the stator assembly group that is located furthest upstream,
- R6 is a radius at a radially outermost point of the leading edge of the blade row of the stator assembly group that is located furthest upstream,
- R7 is a radius at a radially innermost point of a trailing edge of a blade row of the stator assembly group that is located furthest downstream,
- R8 is a radius at a radially outermost point of the trailing edge of the blade row of the stator assembly group that is located furthest downstream,
- wherein RSC indicates a rotor stagger count of a stage and is defined based on the following formula:
- RSC=1/(tan αRI+tan αIE),
- wherein LC defines a load count of a stage and is defined based on the following formula:
- LC=[1/(tan αRE+tan αSI)*(tan αSI)]−[1/(tan αRI+tan αIE)*(tan αIE)]),
- wherein αIE is an averaged angle value of an inflow swirl in front of the rotor assembly group,
- wherein αRI is an effective rotor entry angle and is defined as:
- αRI=βRI−[2/180*π],
- wherein βRE is an effective rotor exit angle and is defined as:
- βRE=βRE+[2/180*π],
- wherein αSI is an effective stator entry angle and is defined as:
- αSI=βSI−[2/180*π],
- wherein αSE is an effective stator exit angle and is defined as:
- αSE=βSE+[2/180*π],
- wherein βRI indicates an averaged entry blade profile angle of the rotor assembly group,
- wherein βRE indicates an averaged exit blade profile angle of the rotor assembly group,
- wherein βSI indicates an averaged entry blade profile angle of the stator assembly group, and
- wherein βSE indicates the averaged exit blade profile angle of the stator assembly group.