| Abstrakt: |
In this paper we explain the development of off-design analysis program for single-spool turbojet engine and its example use for predicting off design performance of a micro turbojet engine based on turbocharger's compressor and turbine performance map. In the current program, matching analysis calculation was done iteratively by using bisection method. To check the accuracy of the results, verification was done by checking the fulfilment of flow and work compatibility. As a study case, matching analysis of a turbojet engine based on turbocharger Garrett GTX5533R with assumed inlet isentropic efficiency 99.9%, combustion chamber pressure losses and efficiency 5% and 95%, exhaust nozzle exit area and isentropic efficiency 0.006 m2 and 95%, mechanical efficiency 98% and fuel LHV 40 MJ/kg has been performed. In static and sea level ISA conditions, the program successfully generates an equilibrium running line which shows the variation of thrust, pressure ratio etc. at different engine speeds. When flight speed and altitude were varied, the program shows the variation of thrust and air mass flow rate with the trend like those in literatures. More engine performance parameters can also be obtained including the variation of turbine inlet temperature and compressor pressure ratio. The program also showed changing flight speed and altitude doesn't significantly change engine pressure ratio if the corrected rpm is constant. Hence, with its ability to calculate and predict the performance of a turbojet engine, the developed program is very useful for turbojet engine development project. [ABSTRACT FROM AUTHOR] |
