Otto Cycle Efficiency Calculator

Inspectable records

Ledger state

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

Area

Thermodynamics, Fluids & Aero

Tranche

tranche-2

Evidence ID

t2-048

Ledger rows

1

No ledger note is attached.

Review findings

The efficiency equation itself passes for the stated air-standard idealization, but the overall specification needs review because work and mean effective pressure are listed as outputs without complete formulas or required inputs. The honest label should explicitly say 'air-standard ideal Otto cycle' and distinguish it from actual gasoline-engine efficiency, which includes non-ideal combustion, heat transfer, pumping, gas-exchange, friction, and finite-rate effects.

Formula and scope findings

• The efficiency formula η = 1 − 1/r^(γ−1) is correct for an ideal air-standard Otto cycle with constant specific-heat ratio γ and compression ratio r = Vmax/Vmin.
• The claimed net-work output has no formula. Under the usual per-unit-mass convention, it should be w_net = η·q_in, where q_in is heat added on the same basis.
• The claimed mean effective pressure output has no formula and cannot be computed from the listed inputs alone. It requires swept volume or specific-volume data: MEP = W_net/Vd for total cycle work, or MEP = w_net/(vmax−vmin) for specific work.
• The specification does not state whether Qin is total heat per cycle, heat per unit mass, or another basis, so the work output is ambiguous.

Unit assumptions

• r is dimensionless and means the geometric compression ratio Vmax/Vmin.
• γ is dimensionless, constant throughout the cycle, and must be greater than 1 for the stated efficiency expression to represent the usual Otto-cycle result.
• Qin must use a clearly specified basis. If Qin is in kJ/kg, net work is in kJ/kg; if Qin is in MJ/kg, net work is in MJ/kg.
• MEP is a pressure and requires a swept-volume basis, such as m³/cycle or m³/kg.
• The default γ = 1.4 is an air-standard approximation, not a universal gasoline-mixture value.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The specification does not state input validation for r<=0 or for the physically invalid range r<1. r=0 causes division by zero, while r<1 produces a mathematically defined but physically invalid negative efficiency. The compression-ratio direction convention is also not stated, allowing the ratio to be inverted and producing a radically different result.

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": {
    "r": 8,
    "gamma": 1.4,
    "Qin": 1000,
    "Qin_units": "kJ/kg"
  },
  "expected_outputs": {
    "eta": 0.5647247184,
    "net_work": 564.7247184,
    "net_work_units": "kJ/kg"
  },
  "working": "γ−1 = 1.4−1 = 0.4. 8^0.4 = 2.297396709. 1/8^0.4 = 0.4352752816. η = 1−0.4352752816 = 0.5647247184. w_net = η·q_in = 0.5647247184·1000 = 564.7247184 kJ/kg."
}

Related workflows

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-tranche2/tranche2-results.json
• BOUNDARY_HAZARD_CATALOG.json