AIRFRAME INSTALLATION EFFECTS ON THE JET EXHAUSTING A COAXIAL NOZZLE SYSTEM OF A GAS TURBINE ENGINE

Jet engine installation effects can significantly affect the behavior of the exhausting flow otherwise axisymmetric for an axial-symmetric nozzle configuration. Considering the problem associated solely with the turbulent jet (i.e. neglecting jet interaction with the airframe or the flight effects) has severe limitations on accurately predicting the real case scenario. It should also be emphasized that the major sources of noise for an aircraft are the high velocity, turbulent hot jets exhausting aircraft's gas turbine engines. Therefore, the prediction of the compressible jet by including wing and pylon effects represents today a topic of high interest in aeroacoustics. A numerical study is carried out for analyzing the flow associated with a separate flow nozzle system with and without installation effects. The Baseline case (without airframe installation) is compared with the case in which only the pylon is considered and with the case where the wing and the pylon are interfering with the jet engine. The simulations are performed with and without forward-flight effects. The tertiary flow increases the length of the potential core region while limiting the radial spread of the jet. The airframe installation effects increase the jet spreading underneath the pylon-nozzle-wing assembly while lowering the production of turbulence in that region. Particle Imaging Velocimetry. experimental flow data are used to validate the computational results for the Baseline and the Pylon cases without the forward-flight effects.