Infrared Characterisation and Prediction of Aviation Turbine Fuel Plume

Broad (3.7 μm - 4.8 μm) as well as narrow band (4.16 μm - 4.24 μm) mid wave infrared characterisation of plume has been reported here. Multiple angular measurements (azimuth) were carried out on a laboratory developed plume source with aviation turbine fuel (ATF) using thermal imaging systems. Correlation of IR prediction to experimental results is the key objectives of this study. As this narrow band covers the blue spike of plume, a comparison of the same with broad band plume contribution has been reported for the first time. Also, a model to simulate the IR radiation of two-dimensional parabolic jet was developed and used to predict spectral contribution from major hydrocarbon fuel combustion products (CO2 and H2O). In addition, it was found that the plume transmission characteristics extracted form imager measurements are qualitatively in agreement with prediction results.

High Temperature Calibration of Thermal Imagers for Infrared Measurements on Military Platforms

Calibration of thermal imaging system is not a straight forward process and hence manufacturers suggest re-calibration at factory itself. However, it is time consuming and expensive. A few research papers refer various approaches to perform low temperature calibration considering the wide requirement of low temperature measurements (typically less than 150 °C). However, no reference is available in open literature about high temperature calibration of thermal imagers. Hence, the possibility of high temperature calibration of thermal imaging systems has been explored using high temperature blackbody sources available at laboratory. With the use of neutral density filters, calibration has been performed in mid-wave (3.7 μm - 4.8 μm) and long-wave (7.7 μm - 9.5 μm) bands of imagers for IR measurements. The developed calibration has also been tested for field measurements