Thermographic Detection of Internal Passageway Blockages

A method of thermal inspection of a component defining at least one internal passageway, the method comprising:

• receiving a continuous sequence of thermal images of at least an exit hole defined by the at least one internal passageway at a surface of the component;
• delivering a pressurized airflow pulse into the at least one internal passageway, the exit hole arranged to expel a film of air across the surface of the component;
• determining a shape of the air film based on at least one thermal image;
• and
• comparing the determined air film shape to a reference shape to determine whether the exit hole meets a specification.

A method of thermal inspection of a component defining at least one internal passageway, the method comprising:

• receiving a continuous sequence of infrared images of a surface of the component;
• delivering a pressurized airflow pulse into the at least one internal passageway;
• receiving a temperature response signal as function of time based on the received thermal images;
• receiving a thermal diffusivity of the component;
• fitting a mathematical expression to the received temperature response signal;
• and
• determining a wall thickness of the component.

A method of thermal inspection of a component defining at least one internal passageway, the method comprising:

• receiving a continuous sequence of infrared images of a surface of the component;
• delivering a pressurized airflow pulse into the at least one internal passageway;
• receiving a temperature response signal as function of time based on the received thermal images;
• executing thermographic signal reconstruction on a monotonically rising portion of the temperature response signal occurring during a time interval starting at an onset of the air pulse delivery and ending at a time when the temperature response signal attains a maximum temperature;
• and
• comparing at least one of a first derivative of the reconstructed temperature response signal with a corresponding first derivative of a reconstructed reference temperature response signal and a second derivative of the reconstructed temperature response signal with a corresponding second derivative of the reconstructed reference temperature response signal to determine if the component meets a specification.

A method of thermal inspection of a component defining at least one internal passageway, the method comprising:

• receiving a continuous sequence of infrared images of a surface of the component;
• delivering a pressurized airflow pulse into the at least one internal passageway;
• receiving a temperature response signal as function of time based on the received thermal images;
• identifying a monotonically rising portion of the temperature response signal occurring during a time interval starting at an onset of the air pulse delivery and ending at a time when the temperature response signal attains a maximum temperature;
• and
• identifying a monotonically falling portion of the temperature response signal occurring during a time interval starting at cessation of the air pulse delivery and ending at a time when the temperature response signal reaches a minimum temperature.

A thermographic testing system comprising:

• a pressurized air source configured to receive fluid communication with a component having at least one internal passageway;
• an infrared camera arranged to capture images of the received component;
• and
• a computing device in communication with the infrared camera, the computing device:
• receiving a continuous sequence of thermal images of at least an exit hole defined by the at least one internal passageway at a surface of the component;
• causing the air source to deliver a pressurized airflow pulse into the at least one internal passageway of the component;
• determining a temperature response signal as function of time based on the received thermal images;
• determining a first derivative of the temperature response signal;
• and
• determining a level of blockage of the at least one internal passageway based on the first derivative of the temperature response signal.