Why does efficiency rise with pressure ratio in the simple formula?

Higher compression raises the mean temperature of heat addition relative to heat rejection in this idealization, similar in spirit to the Carnot limit trend—real engines trade off component losses, material limits, and non-constant cp.

Where are regenerators and intercooling?

Not modeled. Regeneration preheats air before the combustor using turbine exhaust; intercooling splits compression to reduce work—both change the effective cycle on real diagrams.

Brayton Cycle (Gas Turbine)

PV: isentropic compress, isobaric heat in, isentropic expand, isobaric cool — jet/GT core cartoon.

About this model

The Brayton cycle is the idealized open or closed gas-turbine loop: compress the working fluid (often air) nearly isentropically, add heat at nearly constant pressure (combustor or heat exchanger), expand through a turbine isentropically, then reject heat at low pressure—again modeled as isobaric cooling before the compressor inlet. Jet engines add a nozzle after the turbine; the core thermodynamics still echo Brayton. This page uses a normalized PV sketch with γ = 1.4 to show the four legs and compares a cold-air efficiency estimate η ≈ 1 − r_P^{(1−γ)/γ} to a path efficiency from ∮P dV divided by a simple isobaric Q_in proxy—both are pedagogical, not cycle deck software.

Who it's for: Engineering thermodynamics after Otto/Diesel; aerospace and power-plant survey courses.

Key terms

Brayton cycle
Gas turbine
Pressure ratio
Isentropic compressor
Isobaric heat addition
Jet engine core
Cold-air standard

How it works

The Brayton cycle is the archetype of steady-flow power: compress cold air, add heat at roughly constant pressure (combustor), expand through a turbine (or nozzle in a jet). The enclosed PV area is net specific work in this lumped model.

Key equations

T₂s/T₁ = r_P^{(γ−1)/γ}, T₄s/T₃ = r_P^{−(γ−1)/γ}

η_th = [(c_p(T₃−T₄) − c_p(T₂−T₁))] / [c_p(T₃−T₂)]

Frequently asked questions

Why does efficiency rise with pressure ratio in the simple formula?: Higher compression raises the mean temperature of heat addition relative to heat rejection in this idealization, similar in spirit to the Carnot limit trend—real engines trade off component losses, material limits, and non-constant cp.
Where are regenerators and intercooling?: Not modeled. Regeneration preheats air before the combustor using turbine exhaust; intercooling splits compression to reduce work—both change the effective cycle on real diagrams.

Continue with similar topics in this category — or all 46 in Thermodynamics.

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Brayton Cycle (Gas Turbine)

About this model

How it works

Key equations

Frequently asked questions

Related simulators

Diesel Cycle (PV)

Rankine Cycle (Steam)

Vapor-Compression Refrigeration Cycle

Otto Cycle

Stirling Cycle

Carnot Engine

Brayton Cycle (Gas Turbine)

About this model

How it works

Key equations

Frequently asked questions