Aeronautical propulsion system

A propulsion system comprising:

• a drive shaft;
• a drive turbine comprising a drive turbine stator and a drive turbine rotor, the drive turbine rotor being connected to the drive shaft to drive it in rotation relative to the drive turbine stator about a longitudinal axis, the drive turbine rotor comprising a turbine disk and a plurality of turbine blades;
• a fan section comprising a fan rotor and a fan stator, the drive shaft being connected to the fan rotor to drive it in rotation relative to the fan stator about the longitudinal axis;
• wherein the turbine disk is centered on the longitudinal axis and has:
• an inner surface delimiting a circular bore passing through the turbine disk and centered on the longitudinal axis;
• an outer surface delimiting a plurality of slots distributed about the longitudinal axis,
• a bore radius Ra which is defined as a smallest distance between the longitudinal axis and the inner surface of the turbine disk;
• and
• a rim radius Rj which is defined as a smallest distance between the longitudinal axis and the outer surface of the turbine disk;
• wherein at least one turbine blade of the plurality of turbine blades further comprises:
• a root fixed to the turbine disk in a respective slot of the plurality of slots;
• a stilt connected to the root and comprising a platform delimiting a radially inner portion of a flowpath passing through the drive turbine;
• and
• an airfoil connected to the platform and extending within the flowpath, the airfoil having a leading edge, a trailing edge and an end opposite to the platform;
• wherein the flowpath has:
• an outer radius Re which is defined as an average between, on the one hand, a distance between the longitudinal axis and a junction between the end of the airfoil and the leading edge of the airfoil and, on the other hand, a distance between the longitudinal axis and a junction between the end of the airfoil and the trailing edge of the airfoil;
• and
• an inner radius Ri which is defined as an average between, on the one hand, a distance between the longitudinal axis and a junction between the platform and the leading edge of the airfoil and, on the other hand, a distance between the longitudinal axis and a junction between the platform and the trailing edge of the airfoil;
• wherein the drive shaft has a limit speed ω which is defined as the highest speed at which the drive shaft is capable of being driven in rotation about the longitudinal axis during the operation of the propulsion system;
• wherein the bore radius Ra, the rim radius Rj, the outer radius Re, the inner radius Ri and the limit speed ω are such that:
• κ
• *
• N
• ⁢
• 2
• ⁢
• S
• +
• λ
• 1
• ≤
• R
• a
• R
• j
• with:
• N
• ⁢
• 2
• ⁢
• S
• =
• π
• *
• (
• R
• e
• 2
• -
• R
• i
• 2
• )
• *
• ω
• 2
• where:
• ω is expressed in revolutions per minute (rpm);
• κ is −0.0091 rpm−2·m−2;
• λ1 is 0.3;
• Ra, Rj, Re and Ri are expressed in meters;
• and
• N2S is expressed in 106·rpm2·m2;
• wherein the ratio Ra/Rj is strictly positive and strictly less than 1;
• wherein the bore radius Ra is comprised in a range from 0.01 to 0.5 meters inclusive, the rim radius Rj is comprised in a range from 0.01 to 0.5 meters inclusive, the limit speed ω is comprised in a range from 2,000 rpm to 30,000 rpm inclusive, the outer radius Re is comprised in a range from 0.15 to 1.0 meters inclusive, the inner radius Ri is comprised in a range from 0.1 to 0.8 meters inclusive and N2S is comprised in a range from 30*106 rpm2·m2 to 180*106 rpm2·m2 inclusive.

A method for manufacturing a propulsion system, the propulsion system comprising:

• a drive shaft;
• a drive turbine comprising a drive turbine stator and a drive turbine rotor, the drive turbine rotor being connected to the drive shaft to drive it in rotation relative to the drive turbine stator about a longitudinal axis, the drive turbine rotor comprising a turbine disk and a plurality of turbine blades;
• a fan section comprising a fan rotor and a fan stator, the drive shaft being connected to the fan rotor to drive it in rotation relative to the fan stator about the longitudinal axis;
• wherein the turbine disk is centered on the longitudinal axis and has:
• an inner surface delimiting a circular bore passing through the turbine disk and centered on the longitudinal axis;
• an outer surface delimiting a plurality of slots distributed about the longitudinal axis,
• a bore radius Ra which is defined as a smallest distance between the longitudinal axis and the inner surface of the turbine disk;
• and
• a rim radius Rj which is defined as a smallest distance between the longitudinal axis and the outer surface of the turbine disk;
• wherein at least one turbine blade of the plurality of turbine blades further comprises:
• a root fixed to the turbine disk in a respective slot of the plurality of slots;
• a stilt connected to the root and comprising a platform delimiting a radially inner portion of a flowpath passing through the drive turbine;
• and
• an airfoil connected to the platform and extending within the flowpath, the airfoil having a leading edge, a trailing edge and an end opposite to the platform;
• wherein the flowpath has:
• an outer radius Re which is defined as an average between, on the one hand, a distance between the longitudinal axis and a junction between the end of the airfoil and the leading edge of the airfoil and, on the other hand, a distance between the longitudinal axis and a junction between the end of the airfoil and the trailing edge of the airfoil;
• and
• an inner radius Ri which is defined as an average between, on the one hand, a distance between the longitudinal axis and a junction between the platform and the leading edge of the airfoil and, on the other hand, a distance between the longitudinal axis and a junction between the platform and the trailing edge of the airfoil;
• wherein the drive shaft has a limit speed ω which is defined as the highest speed at which the drive shaft is capable of being driven in rotation about the longitudinal axis during the operation of the propulsion system;
• wherein the method comprises dimensioning the at least one turbine blade and dimensioning the turbine disk such that the bore radius Ra, the rim radius Rj, the outer radius Re, the inner radius Ri and the limit speed w are such that:
• κ
• *
• N
• ⁢
• 2
• ⁢
• S
• +
• λ
• 1
• ≤
• R
• a
• R
• j
• with:
• N
• ⁢
• 2
• ⁢
• S
• =
• π
• *
• (
• R
• e
• 2
• -
• R
• i
• 2
• )
• *
• ω
• 2
• where:
• ω is expressed in revolutions per minute (rpm);
• κ is −0.0091 rpm−2·m−2;
• λ1 is 0.3;
• Ra, Rj, Re and Ri are expressed in meters;
• and
• N2S is expressed in 106·rpm2·m2;
• wherein the ratio Ra/Rj is strictly positive and strictly less than 1;
• wherein the bore radius Ra is comprised in a range from 0.01 to 0.5 meters inclusive, the rim radius Rj is comprised in a range from 0.01 to 0.5 meters inclusive, the limit speed ω is comprised in a range from 2,000 rpm to 30,000 rpm inclusive, the outer radius Re is comprised in a range from 0.15 to 1.0 meters inclusive, the inner radius Ri is comprised in a range from 0.1 to 0.8 meters inclusive and N2S is comprised in a range from 30*106 rpm2·m2 to 180*106 rpm2·m2 inclusive.