Stagnation Properties Calculator (Compressible Flow) mechanism

Model scope

Algebraically, both formulas are correct for isentropic flow of a calorically perfect gas: T0/T=1+((γ−1)/2)M² and P0/P=(T0/T)^(γ/(γ−1)). Verdict is NEEDS_REVIEW because the exact unit ambiguity is whether static T is absolute temperature and static P is absolute pressure, and because the required isentropic perfect-gas applicability conditions and honest label are not specified.

• The formulas are standard for isentropic stagnation properties of a calorically perfect gas, but the specification does not state the required assumptions: adiabatic flow, reversibility, no shock losses, and constant gamma.
• The input units are unspecified; static temperature must be absolute temperature and static pressure must be absolute pressure.
• The honest label is missing and should identify these as isentropic perfect-gas stagnation properties, not general stagnation properties across shocks or irreversible flow.

Units and conventions

• Temperature T must be in an absolute scale such as kelvin or degrees Rankine; Celsius and Fahrenheit values cannot be inserted directly.
• Pressure P must be absolute pressure, not gauge pressure.
• Mach number M is dimensionless and conventionally nonnegative.
• Gamma γ is dimensionless, must be greater than 1, and is assumed constant; default air γ=1.4 is appropriate only for a calorically perfect-air approximation.
• T0 has the same absolute-temperature unit as T, and P0 has the same pressure unit as P.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "static_temperature_K": 288.15,
    "static_pressure_Pa": 101325,
    "mach_number": 0.8,
    "gamma": 1.4
  },
  "expected_outputs": {
    "stagnation_temperature_K": 325.0332,
    "stagnation_pressure_Pa": 154453.75
  },
  "working": "T0/T = 1 + ((1.4−1)/2)(0.8)^2 = 1 + 0.2×0.64 = 1.128. T0 = 288.15×1.128 = 325.0332 K. P0/P = 1.128^(1.4/(1.4−1)) = 1.128^3.5 ≈ 1.524340. P0 = 101325×1.524340 ≈ 154453.75 Pa."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The stated pressure formula is undefined at γ=1 because the denominator γ−1 vanishes. The calculator needs explicit validation and rejection for this input.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json