Transonic turbomachine compressor

A transonic compressor for an aircraft turbomachine, said compressor comprising:

• two annular rows of rotor blades;
• and
• one annular row of stator vanes interposed between the rows of rotor blades,
• wherein the rotor blades of the rows of rotor blades each have a radial height and a radially outer end having a velocity,
• wherein the stator vanes of the row of intermediate stator vanes each have a radial height,
• wherein, in a plane that is perpendicular to a radial direction and at a distance to an axis of rotation of the rotor blades, a flow of air leaves the row of stator vanes along a direction that forms a stator outlet airflow angle with an axial direction, and
• wherein when the rows of rotor blades are driven at a rotational speed such that the velocity of the radially outer end of the rotor blades is comprised between 360 m/s and 420 m/s, an average of the stator outlet airflow angle along the height of the stator vanes is greater than 15° and the stator outlet airflow angle is greater than 15° for all distances to the axis of rotation in a radial portion of the stator vanes that is comprised between 60% and 80% of the radial height of the stator vanes.

A turbomachine, said turbomachine comprising:

• a transonic low-pressure compressor;
• a high-pressure compressor;
• a structural casing upstream of the transonic low-pressure compressor;
• and
• an intermediate structural casing between the transonic low-pressure compressor and the high-pressure compressor, the structural casings delimiting a swan-neck-shaped air duct, wherein the transonic low-pressure compressor is arranged directly downstream of the upstream casing and directly upstream of the intermediate casing and wherein the transonic low-pressure compressor comprises two annular rows of rotor blades and one annular row of stator vanes interposed between the rows of rotor blades,
• wherein the rotor blades of the rows of rotor blades each have a radial height and a radially outer end having a velocity,
• wherein the stator vanes of the row of intermediate stator vanes each have a radial height,
• wherein, in a plane that is perpendicular to a radial direction and at a distance to an axis of rotation of the rotor blades, a flow of air leaves the row of stator vanes along a direction that forms a stator outlet airflow angle with an axial direction, and
• wherein when the rows of rotor blades are driven at a rotational speed such that the velocity of the radially outer end of the rotor blades is comprised between 360 m/s and 420 m/s, an average of the stator outlet airflow angle along the height of the stator vanes is greater than 15° and the stator outlet airflow angle is greater than 15° for all distances to the axis of rotation in a radial portion of the stator vanes that is comprised between 60% and 80% of the radial height of the stator vanes.

A method of operating a transonic compressor, wherein the transonic compressor comprises two annular rows of rotor blades and one annular row of stator vanes interposed between the rows of rotor blades,

• wherein the rotor blades of the rows of rotor blades each have a radial height and a radially outer end having a velocity,
• wherein the stator vanes of the row of intermediate stator vanes each have a radial height,
• wherein, in a plane that is perpendicular to a radial direction and at a distance to an axis of rotation of the rotor blades, a flow of air leaves the row of stator vanes along a direction that forms a stator outlet airflow angle with an axial direction,
• said method comprising driving the rows of rotor blades at a rotational speed such that the velocity of the radially outer end of the rotor blades is between 360 m/s and 420 m/s, an average of the stator outlet airflow angle along the height of the stator vanes is greater than 15° and the stator outlet airflow angle is greater than 15° for all distances to the axis of rotation in a radial portion of the stator vanes that is comprised between 60% and 80% of the radial height of the stator vanes.