PREDICTION AND MEASUREMENT OF IR RADIATION FROM JET ENGINE PLUMES

摘要

Propulsion systems, which use hot gases produced by combustion of fuel and oxidizerto generate thrust by expanding these gases through a nozzle, create a typical hot plume,which radiates over a wide spectrum. The most distinct radiation band is located in the IRrange and can be readily measured by various methods. Prediction of the radiometricradiation signature of the hot plume is a complex problem. This procedure involvesprediction of the chemical process of the combustion and the composition of the productsgenerated. The temperature and composition of the plume depends on the operatingconditions of the engine, the interaction of the hot plume with the surroundingatmosphere and the relative velocity of to the surrounding atmosphere. Each molecule,which compose the motor plume, radiate in the IR band when heated at different wavelengths. The strength of the radiated energy depends on the exact composition andtemperature of each molecule in the plume. In this work we compare measurements froma Boeing 777 engine at flight to predictions of the IR signature. The prediction of the IRsignature is based on a detailed simulation of the flow field and IR radiation calculation,which uses the flow field as input. The aim of the investigation was the measurement ofthe radiometric radiation signature of the jet plume and the comparison to CFD flow fieldand radiation calculations which were performed by IMI.