Source: https://guthlabs.ai/docs/instruments/stagnation-properties-calculator-compressible-flow/

instrument / verified-clean

# Stagnation Properties Calculator (Compressible Flow)

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/stagnation-properties-calculator-compressible-flow/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/stagnation-properties-calculator-compressible-flow/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/stagnation-properties-calculator-compressible-flow/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/stagnation-properties-calculator-compressible-flow/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Thermodynamics, Fluids & Aero

**Tranche**: tranche-5

**Evidence ID**: t5-066

**Ledger rows**: 1

No ledger note is attached.

## Review findings

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.

### Formula and scope findings

- 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.

### Unit assumptions

- 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.

## Boundary hardening

**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.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "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."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`