Frequency-mistuned light-weight turbomachinery blade rows for increased flutter stability

An array of flow directing elements for use in turbomachinery devices to increase flutter stability comprising:

• a plurality of flow directing elements mounted on a disk for rotation about an axis;
• said plurality of flow directing elements including at least one high frequency first flow directing element and at least one second low frequency flow directing element;
• said at least one high frequency flow directing element having its three lowest frequency vibratory modes at least 2.0% higher in frequency than the three lowest frequency modes of said at least one low frequency flow directing element;
• and
• each of the at least one high frequency flow directing element and the at least one low frequency flow directing element having a thickness distribution with a local maximum between 20 and 45% of the span.

An array of flow directing elements for use in turbomachinery devices to increase flutter stability comprising:

• a plurality of flow directing elements mounted on a disk for rotation about an axis;
• said plurality of flow directing elements including at least one high frequency first flow directing element and at least one second low frequency flow directing element;
• said at least one high frequency flow directing element having its three lowest frequency vibratory modes at least 2.0% higher in frequency than the three lowest frequency vibratory modes of said at least one low frequency flow directing element;
• said array forming part of a rotor;
• said at least one low frequency flow directing element having a resonant frequency of the lowest frequency vibratory mode which is between a first and a second harmonic of rotor speed;
• the at least one high frequency flow directing element having a resonant frequency of the lowest frequency vibratory mode which is between a second and third harmonic of said rotor speed;
• the at least one high frequency flow directing element having a thickness distribution along its span which is different form a thickness distribution along a span of the at least one low frequency flow directing element;
• and
• the at least one low frequency flow directing element having a local maximum thickness between 20 and 45% of its span.

An array of flow directing elements for use in turbomachinery devices to increase flutter stability comprising:

• a plurality of flow directing elements mounted on a disk for rotation about an axis;
• said plurality of flow directing elements including at least one high frequency first flow directing element and at least one second low frequency flow directing element;
• said at least one high frequency first flow directing element and said at least one low frequency second flow directing element each having a first bending mode, a second bending mode, and a first torsion mode;
• the frequency of the first bending mode of the at least one high frequency first flow directing element being at least 2.0% higher than the frequency of the first bending mode of the at least one low frequency second flow directing element;
• the frequency of the second bending mode of the at least one high frequency first flow directing element being at least 2.0% higher than the frequency of the second bending mode of the at least one low frequency second flow directing element;
• and
• the frequency of the first torsion mode of the at least one high frequency first flow directing element being at least 2.0% higher than the frequency of the first torsion mode of the at least one low frequency second flow directing element.