Physical Transformation AtlasPTA
Pathway · p-e5263f3453 · demonstrated

Combustion MHD generator

Chemical potential differenceCombustionHot gasGas-dynamic expansionBulk fluid flowMagnetohydrodynamic generationCharge carriersElectrical work

Seeded combustion products expand through the combustor's nozzle into a directed supersonic stream that crosses a magnet; electrodes collect the transverse current. NASA Lewis ran cesium-seeded H₂–O₂ combustion products at Mach 2 into a diverging duct of 42 electrodes in a 5 T cryomagnet — the nozzle, not a separate input, makes the flow.

Epistemic state of the route

known constituent relations
7 / 7 established or replicated · weakest constituent established
constituent maturity floor
K4 · experimentally observed
search for this exact route
A recorded pathway or a reviewed search records a demonstration of this composition.
recorded pathway
Combustion MHD generator · prototype
composition maturity
K7 · engineering prototype — MHD generator
recorded-pathway overlap
this route is the recorded pathway Combustion MHD generator
regimes the implementation establishes
  • thermodynamic:expansion-pressure-drop · implementation process · combustor / nozzle / generator inlet: the pressurised seeded combustion products expand through the nozzle to the generator inlet; Smith 1979 reports the nozzle designed for Mach 2 and Mach 2 flow entering the MHD duct · refs [3]
A physical process inside the named implementation that establishes a regime its route requires (pass 43) — never an off-route load and never a conversion stage the route should carry.
route-level evidence
2 sources for the complete composition · 7 cited by the constituent steps
boundaries and interfaces
BOUNDARY compatible · 1 recorded interface
  • mhd-plasma-electrodes · electrode contact · demonstrated · plasma-channel → electrode · carries Charge carriers · within mhd-produces
    the conducting plasma crosses the magnetic field in the generator channel; the induced current is collected at solid electrodes into the external circuit
    the solid electrode is a boundary of the plasma channel, not the active medium of the MHD effect
    Rosa's experimental MHD work (Physics of Fluids 4, 182–194, 1961: an experimental 10 kW generator) used a conducting high-temperature gas and electrodes; the electrode boundary must not make the plasma conversion step inherit state-solid.
    evidence: Physical principles of magnetohydrodynamic power generation

Explorematrix context · physics checks · steps · route evidence · constituent evidence · cite

Matrix context

D = disequilibrium row · C = coupling family column. A cell reads the state of the atlas for that pair.

D.05 × C.29 · Chemical potential difference × Thermochemicalfamily: ThermochemicalD.05 × C.08 · Chemical potential difference × Heat engine (thermomechanical)family: Heat engine (thermomechanical)D.05 × C.25 · Chemical potential difference × Magnetohydrodynamicfamily: Magnetohydrodynamic

Typed bounds on this route

Every limit the atlas holds for this route, as constraint records: reached through bounded_by claims on the route's own entities. Hard bounds (an upper bound or a formula) decide the thermodynamic-bound check above; benchmarks, constitutive relations and resource limits are listed and never decisive. No prose limit exists anywhere (pass 42).

  • Carnot limit · formula-bound · hard, applies to this route
    η ≤ 1 − T_c/T_h for any heat engine between reservoirs at T_h and T_c

Steps

  1. 01
    Chemical potential difference —drives→ Combustionestablishedclaim record
    chemical → thermal · loss to radiative
    • fuel, oxidiser and an ignition source; flame temperature 1500–2500 K
    gas · above ~700 K
    refs [1]
  2. 02
    Combustion —produces→ Hot gasestablishedclaim record
    thermal → thermal
    refs [1]
  3. 03
    Hot gas —drives→ Gas-dynamic expansionestablishedclaim record
    thermal → kinetic · loss to thermal
    • the gas has an upstream pressure state above the downstream nozzle or duct pressure
    gas
    refs [2] [3]
  4. 04
    Gas-dynamic expansion —produces→ Bulk fluid flowestablishedclaim record
    kinetic → kinetic
    • a directed high-speed gas stream leaves the nozzle — the disequilibrium whose content is bulk fluid motion
    refs [3] [2]
  5. 05
    Bulk fluid flow —drives→ Magnetohydrodynamic generationestablishedclaim record
    kinetic → electrical · loss to thermal
    • an electrically conducting fluid — seeded combustion plasma or liquid metal — crossing a strong magnetic field between electrodes
    bulk flow required · magnetic field required
    refs [4] [5] [6]
  6. 06
    Magnetohydrodynamic generation —produces→ Charge carriersestablishedclaim record
    electrical → electrical
    refs [4] [5]
  7. 07
    Charge carriers —converts into→ Electrical workestablishedclaim record
    electrical → electrical · loss to thermal
    • carriers driven through an external load at the potential difference the source maintains
    refs [7]

Evidence for the complete composition · 2

  1. [4]
    R. J. Rosa. Physical principles of magnetohydrodynamic power generation (1961)
    Physics of Fluids 4, 182–194 · doi:10.1063/1.1724426 · crossref ✓ 2026-09-19 · record
  2. [3]
    J. Marlin Smith. Preliminary results in the NASA Lewis H2-O2 combustion MHD experiment (1979)
    NASA Technical Memorandum 79135 (E-9983); prepared for the 18th Symposium on the Engineering Aspects of Magnetohydrodynamics, Butte, Montana, June 18–20, 1979 · ntrs.nasa.gov/citations/19790014726 · record

Evidence for the constituent relations · 7

  1. [1]
    A. Bejan. Advanced Engineering Thermodynamics (4th ed.) (2016)
    Wiley · doi:10.1002/9781119245964 · crossref ✓ 2026-09-19 · record
  2. [2]
    NASA Glenn Research Center. Nozzle Design (Beginner's Guide to Aeronautics) (2024)
    NASA Glenn Research Center, Beginner's Guide to Aeronautics; page dated 2021-08-06, modified 2024-09-12 · www1.grc.nasa.gov/beginners-guide-to-aeronautics/nozzle-design/ · record
  3. [3]
    J. Marlin Smith. Preliminary results in the NASA Lewis H2-O2 combustion MHD experiment (1979)
    NASA Technical Memorandum 79135 (E-9983); prepared for the 18th Symposium on the Engineering Aspects of Magnetohydrodynamics, Butte, Montana, June 18–20, 1979 · ntrs.nasa.gov/citations/19790014726 · record
  4. [4]
    R. J. Rosa. Physical principles of magnetohydrodynamic power generation (1961)
    Physics of Fluids 4, 182–194 · doi:10.1063/1.1724426 · crossref ✓ 2026-09-19 · record
  5. [5]
    L. D. Landau, E. M. Lifshitz, L. P. Pitaevskii. Electrodynamics of Continuous Media (Course of Theoretical Physics, Vol. 8, 2nd ed.) (1984)
    Pergamon · book, no DOI · record
  6. [6]
    NASA Lewis Research Center, Electromagnetic Propulsion Division. Lewis Tech Preview: Research Nonequilibrium MHD Power Generator Facility
    NASA Lewis Research Center tech preview N-422 67/11-39 (one page; the date is not printed beyond that document code) · www1.grc.nasa.gov/wp-content/uploads/MHD-Power-Generator-Facility-Tech-Preview.pdf · record
  7. [7]
    N. W. Ashcroft, N. D. Mermin. Solid State Physics (1976)
    Holt, Rinehart and Winston · book, no DOI · record

Cite this route

Physical Transformation Atlas (2026). route p-e5263f3453: Combustion MHD generator. Dataset revision rbfbfcbb70e57 (hash of the canonical data). https://physical-transformation-atlas.wldud5192.workers.dev/path/e5263f3453

Ids and matrix addresses are stable across revisions; the revision hash identifies the exact canonical files the record was compiled from and is meta.data_hash in every /api export. Reuse terms: see the license field in any export.