Exergetic Performance of a Low Bypass Turbofan Engine at Takeoff Condition

Abstract

In this article, exergetic methodology is applied for a low bypass turbofan engine at maximum power setting. The engine is a low-bypass (0.96–1) turbofan engine and its variants fitted to the 737-100/200 all comprise six low-pressure compressor (LPC) stages, seven high-pressure compressor (HPC) stages, a single HP turbine (HPT), and finally three LPT stages. At the end of the analysis, the most irreversible units in the system are found to be the combustor and the fan/LPC, with exergy loss rates of 18.7 and 2.486 MW, respectively. The exergy efficiencies of the fan/LPC, the HPC, and combustor are 0.856, 0.845, and 0.744, respectively. For the HPT and LPT, the exergy efficiencies are calculated to be 0.98 and 0.963, respectively.

Nomenclature

c _p :

Specific heat (kJ (kg K)⁻¹)

E :

Energy rate (MW)

ex:

Specific exergy (kJ kg⁻¹)

$\dot{E}x$ :

Exergy rate (MW)

f:

Fuel-air ratio; fuel exergy factor

h_PR :

Fuel heating value (kJ kg⁻¹)

H:

Enthalpy (kJ)

I:

Irreversibility rate (kW)

ke:

Kinetic energy

$\dot{m}$ :

Mass flow rate (kg s⁻¹)

A:

Area (m²)

M_A :

Molecular weight

pe:

Potential energy

P:

Pressure (bar or kPa); product exergy

R:

Specific gas constant (kJ (kg K⁻¹)), diameter (m)

S:

Entropy (kJ K⁻¹)

T:

Temperature (K)

$\dot{W}$ :

Work rate (MW)

η :

Efficiency

ρ:

Air density (kg m⁻³)

a:

Air

ch:

Chemical

dest:

Destruction

f:

Fuel

gen:

Generated

k:

kth component

LPC:

Low-pressure compressor

HPC:

High-pressure compressor

LPT:

Low-pressure turbine

HPT:

High-pressure turbine

in:

Inlet

ke:

Kinetic energy

LD:

Loss and destruction

kn:

Kinetic

out:

Outlet

per:

Perfect

ph:

Physical

pe:

Potential energy

tot:

Total

A:

Area, m²

c_p :

Specific heat, J kg⁻¹ °C

h:

Heat transfer coefficient, W m⁻² °C