Aero-thermal Analysis of Insulation to Protect Exhaust Ducts of A Pusher Turbo Prop Engine Aircraft

Engine exhaust stubs should be insulated to minimize heating of the nacelle. Nacelle material being aluminium the temperature rise due to hot exhaust gases should not deteriorate the characteristics of the aluminium material. To meet this requirement a heat shield should be installed on the portion of the engine exhaust duct internal to the nacelle. This paper describes aero-thermal relations used in selecting the insulation to protect exhaust ducts, assuming only the air flow due to natural convection and the emissivity of the duct material and the constraint is that the target cold surface temperature should be less than 200°C. Having chosen the insulation, tests were conducted on the aircraft and the results show that the objective is met with the calculated target cold surface temperature limit. \ud \u