Neqsim Jet Fire Radiation Screening

Jet Fire Radiation Screening

Use this skill for public, educational jet-fire thermal-radiation screening. It estimates the radiative heat flux at a given distance, or the distance to a target flux, from an ignited gas release using the open single-point-source flame model, so an agent can scope a fire hazard zone before detailed consequence analysis.

When to Use

• When a user asks roughly what radiation flux reaches a target distance.
• When an agent needs a quick distance to a personnel or equipment thermal limit.
• When examples must run without confidential plant layout or fire-tool data.

Inputs

• release_rate: burning mass release rate mdot in kg/s.
• heat_of_combustion: lower heat of combustion Hc in J/kg, default 50e6.
• radiant_fraction: fraction of heat released as radiation Xr, default 0.2.
• transmissivity: atmospheric transmissivity tau, default 1.0.
• distance: distance to the target in m (for flux), optional.
• target_flux: target radiation flux in kW/m2 (for distance), optional.

Outputs

• total_radiative_power_kw: total radiative power emitted by the flame.
• radiation_flux_kw_m2: flux at distance, or null if no distance given.
• distance_to_target_m: distance to target_flux, or null if no target given.
• radiation_warning: ok, watch, high, severe, or no-distance.
• assumptions: public assumptions used by the placeholder model.

Engineering Method

The Python class JetFireRadiationModel uses the public single-point-source flame model:

• the radiative power uses Q_rad = tau * Xr * mdot * Hc.
• the flux at a distance uses q = Q_rad / (4 pi r^2).
• the distance to a target flux inverts the same relation: r = sqrt(Q_rad / (4 pi q_target)).
• the warning compares the flux to public thermal limits: a personnel limit (default 4.7 kW/m2), an equipment limit (default 12.5 kW/m2), and a 37.5 kW/m2 severe limit.

This is educational and screening-only logic. It assumes full combustion of the released mass, isotropic emission with no view factor, and no flame shape, length, or wind tilt. It is not a replacement for validated fire modelling, solid-flame or CFD radiation tools, and qualified safety review.

Python Usage Pattern

from jet_fire_radiation_screening import JetFireRadiationModel

model = JetFireRadiationModel()
result = model.evaluate(
    release_rate=10.0,
    target_flux=12.5,
)

print(result.total_radiative_power_kw)
print(result.distance_to_target_m)
print(result.radiation_warning)

Related NeqSim Functionality

For validated fire-consequence behaviour, redirect to existing NeqSim classes:

• neqsim.process.safety.fire.JetFireModel — jet-fire flame and radiation modelling.
• neqsim.process.safety.fire.PoolFireModel — pool-fire radiation modelling.
• neqsim.process.safety.fire.BLEVECalculator — BLEVE fireball thermal dose.

This skill is a public radiation triage layer that decides when to invoke those validated fire classes.

Validation Checklist

• Release rate and heat of combustion are positive.
• Radiant fraction and transmissivity are in (0, 1].
• At least one of distance or target_flux is supplied for a useful result.
• Tests cover radiative power, flux at distance, distance to target, and invalid input.
• Real fire analysis is redirected to validated NeqSim fire classes and qualified review.

Common Mistakes

Limitations

• Point-source emission; no flame length, shape, or view factor.
• No wind tilt, lift-off, or partial combustion.
• No transient or impinging-fire effects.

References

• NeqSim repository: https://github.com/equinor/neqsim
• NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md