Effects of isentropic efficiency of turbomachinery components on entropy production for small turbojet engine

Nomenclature

Alt

= Altitude;

LHV

= Lower heating value (kJ/kg);

M

= Mach number;

MIL

= Military;

PE

= Propulsive efficiency, %;

PSO

= Particle swarm optimization;

s

= Entropy (kJ/kg.K);

SEP

= Specific entropy production;

TH

= Thermal;

TIE

= Turbine isentropic efficiency;

TP

= Total power, kW;

TE

= Thermal efficiency, %;

OE

= Overall efficiency, %;

WER

= Wasted energy ratio;

WP

= Waste power, kW;

FP

= Fuel power, kW; and

CIE

= Compressor isentropic efficiency.

Symbols

$\dot{m}$

= Mass flow rate (kg sn⁻¹);

V

= Velocity, m.s⁻¹;

τP

= Thrust power, kW; and

τ

= Thrust, N.

Subscripts and superscripts

C

= compressor;

e

= Exhaust or exit;

f

= Fuel; fuel-air ratio;

I

= Inlet;

o

= Outlet;

t

= turbine;

th

= Thermal;

tot

= Total;

0

= Environment; and

P

= Propulsive.

Introduction

Considering categories of the aviation field, it is generally split into three parts such as military, commercial and general. The number of air vehicles has increased owing to rising transportation activities in recent years (Altuntas, 2020). Due to usage in these aeronautic applications and power generation, a small-size turbojet engine that is a branch of gas turbine engines has become popular day by day. Progress in air transportation depends on innovations of propulsion systems. To attain higher speeds over long-haul distances becomes possible with significant advances in these systems (Sehra and Whitlow Jr, 2004). Also, to meet the multi-mission requirements of fighters, turbojet engines should overcome technological challenges. Relatively high power/weight ratio of turbojet engines is to be important aspect so that human prefers to these systems. The most important feature of jet engines is their relatively high performance. Researchers try to find operation points where jet engines have high efficiency of their components. The higher the efficiency, the lower the fuel consumption, thereby the lower environmental impact (Rosen, 2002; Tuzcu et al., 2020). To obtain environmental benign turbojet engine depends on decreasing system irreversibility to a minimum as possible. Due to the rising demand to the unmanned aerial vehicle, the number of gas turbines powering these systems have increased for two decades. Considering the increasing aviation activities, it can be expressed that environmental effects resulting from these...