Military aircraft employ aero-gas turbines fitted with afterburners to meet the requirements of rapid increase in thrust for flight operations that involve combat maneuvers. The airflow rate through an aero-gas turbine remains unchanged even after an afterburner is invoked to ensure that there is no disruption in the turbomachinery operating characteristics. Triggering of flow instabilities leading, in turn, to combustor instabilities could occur due to the incorrect Rayleigh heat addition in the constant area afterburner. In normal operation, the propelling nozzle should be correctly opened up to pass the increased volumetric flow rate of the heated air due to heat addition in the afterburner. Any mismatch could result in violent flow instabilities including possible fan stall in a turbofan. The processes of triggering instabilities by sub/supercritical Rayleigh heat addition have been characterized. The gas dynamic equivalence of secondary mass addition to heat addition has been analyzed and experimentally validated in a model afterburner combustion test rig. Consequently, sudden sub/supercritical heat addition in an afterburner with its corresponding propelling nozzle closure has been studied and characterized for the equivalent mass addition in a separate model afterburner simulation test rig.
Triggering of Flow Instabilities by Simulated Sub/Supercritical Rayleigh Heat Addition in an Aero-Gas Turbine Afterburner
Lect.Notes Mechanical Engineering
01.08.2020
13 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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