Optical stall precursor sensor apparatus and method for application on axial flow compressors

A stall precursor detector system for an axial flow compressor, comprising:

• at least one optical sensor to detect the deflection of an individual rotating airfoil of said compressor;
• means for comparing the deflection of the individual airfoil with a predetermined value, said predetermined value being indicative of onset of a stall in said compressor;
• and
• means for identifying onset of a stall and producing a stall onset signal if said deflection is greater than said predetermined value.

A stall warning system for an axial flow compressor, comprising:

• at least one optical sensor to detect and measure the deflection of an individual airfoil of said compressor;
• means for comparing said deflection of the individual airfoil with a predetermined value indicative of a stall onset;
• means for identifying onset of a stall if said measured deflection is greater than said predetermined value;
• and
• a feedback control system for initiating corrective actions to prevent a subsequent compressor surge upon identifying a stall onset.

A method for detecting a stall onset in an axial flow compressor system comprising,

• (a) providing at least one optical sensor to measure the deflection of an airfoil, said deflection caused by a rotating stall cell;
• (b) comparing the deflection as measured in step (a) with a predetermined value indicative of a stall;
• (c) identifying onset of a stall if said measured deflection is greater than said predetermined value;
• said deflection of the airfoil being measured by measuring the time of arrival of the airfoil with respect to a reference.

A stall precursor detector system for an axial flow compressor, comprising:

• at least one optical sensor to detect the deflection of a rotating airfoil of said compressor;
• means for comparing the deflection with a predetermined value, said predetermined value being indicative of onset of a stall in said compressor;
• means for identifying onset of a stall and producing a stall onset signal if said deflection is greater than said predetermined value;
• a control system for initiating corrective actions to prevent a subsequent compressor surge if said deflection is greater than said predetermined value;
• and
• a system selector means for applying the stall onset signal to provide a warning of said stall onset.

A method for detecting a stall onset in an axial flow compressor system comprising,

• (a) providing at least one optical sensor to measure the deflection of a discrete airfoil, said deflection caused by a rotating stall cell;
• (b) comparing the deflection as measured in step (a) with a predetermined value indicative of a stall;
• and
• (c) identifying onset of a stall if said measured deflection of the discrete airfoil is greater than said predetermined value.