Brayton Cycle 3D Simulator — Gas Turbine Pressure Ratio & Efficiency Interactive

Interactive 3D cutaway stationary gas turbine simulator, a Curves & measurements analysis tab with live charts and model equations, an Experiments tab with four guided fixtures and a model-verification bench, and a Learn & assess tab with lessons and a knowledge-check quiz.

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About the Brayton Cycle 3D Simulator

This simulator inspects a cutaway stationary gas turbine: a compressor raises inlet air to pressure, a combustor adds heat at that pressure, and a turbine expands the hot gas, driving both the compressor and a useful shaft load. Change pressure ratio, firing temperature and component efficiencies, then compare gross turbine output, compressor demand and net useful shaft power.

What the simulator shows

• A real-time 3D cutaway gas-turbine workbench (compressor, combustor, turbine and output shaft) with home view, focus-selected-part, auto-rotate, expand, show/hide outer shell and hide-labels scene tools; state numbers match a reference T-s diagram and shaft rotation/flow speed are illustrative. • Experiment controls: pressure ratio, firing (turbine inlet) temperature, compressor isentropic efficiency, turbine isentropic efficiency, combustor pressure loss and mass flow rate sliders, plus pause/resume, single-step and 60 s-step buttons, six playback speeds for the flow animation, and restart/animate/stop actions. • A Curves & measurements analysis tab with two live charts (specific work allocation between turbine and compressor; a pressure-ratio sweep), the underlying air-standard Brayton-cycle equations, and snapshot readouts (turbine work, compressor work, net shaft work, heat input and thermal efficiency). • An Experiments tab with four guided fixtures (a reference gas turbine, an ideal Brayton benchmark with no losses, a case that cannot sustain positive output, and mass-flow scaling of the same operating point) and a Model verification bench with a timestamped event log and copyable trial report. • A Learn & assess tab with four guided lessons, a knowledge-check quiz with reset, and a written model-scope statement linking to a Brayton-cycle reference.

Compressor demand and the optimum pressure ratio

Unlike the Rankine cycle's liquid-pumping pump, the Brayton cycle's compressor works on compressible gas and consumes a substantial fraction of the turbine's gross output — often a third or more — which is why compressor demand is a major cost the simulator tracks explicitly on the specific-work-allocation chart. Raising pressure ratio increases both the compressor work required and the turbine work available, and the pressure-ratio-sweep experiment reveals that net specific work has an optimum pressure ratio for a given firing temperature: too low a ratio limits turbine work, while too high a ratio drives compressor demand up faster than turbine output grows.

The ideal-Brayton-benchmark experiment sets component efficiencies to their ideal (loss-free) values, isolating the cycle's fundamental thermodynamic behavior from the additional efficiency penalty that real, non-ideal compressors and turbines impose.

When the cycle cannot run, and model scope

If the firing temperature is set below the compressor's outlet temperature, the combustor would need to remove heat rather than add it — an invalid firing setpoint that the simulator explicitly flags rather than silently computing a nonphysical result, demonstrated in the cannot-sustain-output experiment. When net work comes out negative, the model reports it as an external shaft demand: thermal efficiency becomes unavailable and animation is blocked, since a machine consuming net work is not, in this model's sense, running as a power-producing gas turbine.

This is a steady air-standard open gas-turbine representation using constant specific heat and specific-heat ratio, prescribed mass flow, compressor and turbine efficiencies, and a combustor pressure loss. Heat addition substitutes directly for combustion — fuel mass, chemical composition, emissions and high-temperature property variation with composition are not modeled. There is no regeneration, intercooling, mechanical or electrical losses, surge, startup transients or rotational speed dynamics. The T-s plot joins state endpoints with guide lines rather than exact irreversible process paths, and the exhaust-to-inlet line on that plot represents external heat rejection rather than a physical return pipe.

Frequently asked questions

Why does the compressor consume so much of the turbine's output in a gas turbine cycle?

The compressor works on compressible gas rather than liquid, so raising its pressure requires substantial work — often a third or more of the turbine's gross output. This is fundamentally different from the Rankine cycle's pump, which compresses nearly incompressible liquid and needs comparatively little work.

Is there an ideal pressure ratio for maximizing net work in a Brayton cycle?

Yes — for a given firing temperature, net specific work rises with pressure ratio up to a point, then falls as compressor work grows faster than the additional turbine work it enables. The pressure-ratio-sweep experiment traces this curve directly.

What happens if the firing temperature is set lower than the compressor's outlet temperature?

The simulator flags this as an invalid firing setpoint rather than computing a nonphysical result, because the combustor would need to remove heat instead of adding it — which contradicts how a combustor operates in this model.

Does this Brayton cycle simulator model actual fuel combustion and emissions?

No. Heat addition in the combustor substitutes directly for combustion in this air-standard model; fuel mass, chemical composition, emissions and high-temperature property variation with gas composition are not represented.

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