Aero-thermal investigation of thermal interactions between turboprop engine exhaust and selected parts of the airplane skin for tractor configured aircraft

Abstract

Purpose Development or upgradation of airplanes requires many different analyses, e.g. thermal, aerodynamic, structural and safety. Similar studies were performed during configuration change design of commuter category aircraft equipped with pusher turboprop engines. In this paper, thermo-fluid analyses of interactions of the new propulsion system in tractor configuration with selected elements of airplane skin are carried out. This study aims to check the airplane skin material, and its geometry, including the Plexiglas passenger window material degradation, due to hot exhaust gas plume impingement. The impact of change in exhaust stub angle and asymmetric inboard-outboard stubs on the jet thrust at various flight operating conditions like minimum off-route altitude and cruise performance is assessed. Design/methodology/approach Commercial software-based numerical models were developed. In the first stage, heat and fluid flow analysis was performed over a twin-engine airplane’s nacelle, wing and center fuselage with its powerplant mounted in the high wing configuration. Subsequently, numerical simulations of thermal interactions between the hot exhaust gases, which leave the exhaust system close to the nacelle, flaps and the center fuselage, were estimated for various combinations of exhaust stub angles with asymmetry between inboard-outboard stubs at different airplane configurations and operating conditions. Findings The results of the simulations are used to recommend modifications to the design of the considered airplane in terms of material selection and/or special coatings. The importance and impact of exhaust jet thrust on the overall aircraft performance are investigated. Originality/value The advanced numerical model for the exhaust jet-airplane skin thermal interaction was developed to estimate the temperature effects on the propeller blades and aircraft fuselage surfaces during different flight operating conditions with multiple combinations of stub orientations.

Engine Exhaust Stub Sizing for Turboprop Powered Aircraft

“…Figure 6 shows a good exhaust duct design with longer cutback length, which favors flow turning at the inner radius, and thus improves performance for aircraft configuration. To design exhaust stubs for different aircrafts, special attention should be paid to the exhaust stub angle, for hot exhaust gas would impinge on aircraft surfaces and structures, and exhaust stubs should not create any additional external aerodynamic drag [11][12][13][14][15]. The design of internal flow ducts should minimize the pressure loss induced by the flow separation from the internal walls of the duct.…”