A transient 0-D thermodynamic solver for pressure, temperature, heat release, and emissions estimates. Select crank-angle steps down to 0.25° across a 720° four-stroke cycle, directly in your browser.
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Explore adjustable combustion and thermodynamic models. Check assumptions and calibrate predictions against measurements for your application.
JANAF/NASA polynomial thermochemistry — no hardcoded k values, no simplified assumptions.
Every pressure trace comes from integrating real thermodynamics across the cycle, not interpolating between pre-baked results.
x_b burns with crank angle θ — integrated alongside the first law of thermodynamics to produce the pressure trace you see on every run.
That heat-release rate feeds directly into a first-law energy balance on the cylinder control volume, solved across 2,881 samples at the finest 0.25° setting over a 720° cycle using JANAF/NASA polynomial thermochemistry for each fuel — not constant specific heats.
Scroll to turn the crank — the log p · log V trace is computed live from the same first-law energy balance this simulator solves.
The intake valve opens and the descending piston draws in fresh charge at ≈0.95 bar — the flat lower line of the loop.
Both valves seal. The rising piston compresses the charge polytropically — a straight line in log-log space, pressure climbing toward autoignition.
Fuel burns following the Wiebe function above; pressure spikes past 60 bar. The loop area is the net work — the same convention as the arrows in our logo.
The exhaust valve opens at BDC, pressure collapses, and the rising piston clears the burned gas. Ready to repeat.
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