High-speed IR monitoring of a turbojet engine gas flow using an uncooled MWIR imaging sensor

Several sensors are used during the performance tests of a turbojet engine to record parameters such as temperature, pressure, vibration, etc. However, most of these sensors have long time constants and are unable to measure fast transients and fluctuations. In this paper we show an alternative sensor to characterize some phenomena observing the flow resulting from the combustion at the outlet of a turbojet engine, using a very high-speed uncooled MWIR COTS imaging sensor from New Infrared Technologies, which provides over 1,600 fps. The experiments include monitoring of flow stability during a long observation time (accelerations and stationary regimes), and higher frequency events such as surges. Compressor surges produce extremely loud bangs from the engine, and may be accompanied by a fast increment of the exhaust gas temperature and an increase in rotor speed due to the reduction in work done by the stalled compressor, causing severe stresses within the engine from the intense aerodynamic buffeting within the compressor. The main conclusion of this study is the demonstration of the potential and worthiness of high-speed uncooled IR imagers for detecting and analyzing fast transient events and stationary events during combustion test studies from thrusters such as turbojets and rockets.