Preliminary Design of a Short Afterburner for Single-Spool Expendable Turbojet Engine

摘要

A theoretical study related to a short afterburner design is presented in this paper. The objective is to enhance the performance of an existing single-spool expendable turbojet engine in terms of thrust, with a fixed-area exit nozzle. The expendable turbojet engines are generally used in the reconnaissance air vehicles where the engine is positioned in the fuselage near the center of gravity. Consequently, a longer exhaust duct exists before of the nozzle section which can house a short afterburner. An in-house FORTRAN language code is developed to evaluate the performance of single-spool expendable turbojet engine without afterburner and the results of the code are validated with the available experimental data. A short afterburner is designed based on the available length constraints. As a result of the limited length available for the afterburner, combustion chamber has to be considerably shorter than those usually used in the afterburners. Afterburner pressure loss and efficiency is calculated iteratively by using afterburner inlet conditions. It is found that by adding the designed short afterburner, about 20% increase in the thrust is achieved at the expense of 50% increase in specific fuel consumption.