Optimization of turbojet engine cycle with dual-purpose PSO algorithm

M.R Ahadi Nasab,M.A Ehyaei

doi:10.1051/meca/2019029

M.R Ahadi Nasab, M.A Ehyaei

Open Access

https://doi.org/10.1051/meca/2019029

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Journal: Mechanics & Industry	Publication Date: Jan 1, 2019
Citations: 4	License type: cc-by

Affiliation: Islamic Azad University, Tehran

Abstract

In this article, the J85-GE-21 turbojet engine for an altitude of 1000–8000 m, with the speed of 200 m/s and at 10, 20, and 40 °C, was provided, and then, based on the objective functions, the above system was optimized using particle swarm optimization method. For the purpose of optimization, the Mach number, compressor efficiency, turbine efficiency, nozzle efficiency, and compressor pressure ratio were assumed to be in the range of 0.6–1.4, 0.8–0.95, 0.8–0.95, 0.8–0.95, and 7–10, respectively. The highest exergy efficiency of 73.1% for different components of the engine at sea level and speed of 200 m/s belonged to the diffuser. Second and third to it were nozzle and combustion chamber with 68.6 and 51.5%, respectively. The lowest exergy efficiency of 4% belonged to the compressor, and the second to it was the afterburner with 11.6%. Also, the values of entropy production and efficiency of the second law of thermodynamics were 1176.99 and 479 K/W, respectively, prior to optimization, which were respectively changed to 1129 and 51.4 K/W postoptimization. Obviously, the entropy production is reduced, while the efficiency of the second law of thermodynamics is increased.

Highlights

The engine mounted on an airplane is used to produce thrust
The ideal jet-propulsion cycle is different from the ideal Brayton cycle from the aspect that in jet-propulsion cycle the gases are not expanded to the level of the turbine’s ambient pressure; they are expanded to the extent that the power generated by the turbine is exactly of the same extent needed for ignition of compressor and other auxiliary tools such as the generator and hydraulic pump, i.e., the net output work from jetpropulsion is zero [1]
The exergy and energy equations of the system were first written, and based on these equations, a model of energy was performed in MATLAB

Summary

Introduction

The engine mounted on an airplane is used to produce thrust. The exhaust gases from the aircraft engine, which are intensely pushed back from the engine nozzle, cause the aircraft to move forward, which allows air to pass above the airplane’s wing. The pressure on the topside of the wing is lower than that on the underside, and a lifting force would be generated, called “lift force,” which causes the aircraft to ascend. Most of the modern aircrafts use the gas turbine engines for generation of thrust force, since they are light and compact and their power-to-weight ratio is high. The ideal jet-propulsion cycle is different from the ideal Brayton cycle from the aspect that in jet-propulsion cycle the gases are not expanded to the level of the turbine’s ambient pressure; they are expanded to the extent that the power generated by the turbine is exactly of the same extent needed for ignition of compressor and other auxiliary tools such as the generator and hydraulic pump, i.e., the net output work from jetpropulsion is zero [1].

Objectives

Results

Conclusion