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Thermoacoustic hot-head shroud: flame shroud and flue for a vertical 2 in tri-clamp core

How do I heat the hot exchanger of a vertical thermoacoustic core with a propane torch? · Hardware · basis: Bore = ASME BPE 2 in tube OD Ø50.8; positions from the loop layout in tools/gen_ta_family.py; ISO 273 medium clearance for M4

Long Earth Society build part. The flame shroud on my looped thermoacoustic engine. The engines

Exact dimensions. Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part. Mating features

sizes
5 in table

Notes

  • The loop's core stands vertical with its hot exchanger above the thermal buffer tube, hot end up, so the buffer tube does not convect (Backhaus & Swift ran theirs the same way). A torch cannot fire straight up at the middle of a vertical tube, so the shroud does it: a closed band round the tube at the hot exchanger, with a flue that comes down beside the loop to a torch standing on the bench.
  • Flame and hot gas go up the Ø35 flue (132.6 mm), into the chamber, round the tube over a 40 mm band (the top 20 mm of the buffer tube, the hot exchanger, the first 10 mm of the regenerator) and out of the vents in the top. No clamp, gasket or jacket is inside the band.
  • Two halves split across the tube: the front half carries the flue; one M4 × 25 and nut each side close them on the tube. The end walls are bored at the tube OD.
  • What it is made of is the builder's choice; the file is the geometry. It runs at flame temperature.

Sizes

featurevalue
band40 tall, Ø80 round the tube
flueØ40 / Ø35 × 132.6, 100 in front of the tube axis
walls2.5
vents8 × Ø6 on r 31.5, 3 × Ø8 over the lobe
boltsM4 × 25 + nut, one each side

Mating features

Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.

featureexactmates withfitfiles
end-wall boresØ50.82 in tube ODslideall
split1.0 total (0.5 per half)the other halfclampall
ear holesØ4.5M4 clearance (ISO 273 medium)designedall
flueØ40 / Ø35torch flame from the torch stand below (no contact)designedta-shroud-2in-front*
vents8 × Ø6, 3 × Ø8exhaust (no contact)designedall

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

J. Acoust. Soc. Am. (S. Backhaus, G. W. Swift)A thermoacoustic-Stirling heat engine: Detailed study, JASA 107(6), 3148 (2000): regenerator |Z| 15–30 ρc/A with p and U nearly in phase, thermal buffer tube, inertance and compliance, jet pump against Gedeon streamingPDFjournal article; numbers cited verify
Long Earth SocietyEngine buildsweb, videoLES site

Free files

★ Free files 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

ta-shroud-2in-frontfront half (y ≥ 0.5): 40 tall band round the Ø50.8 tube, Ø80 chamber joined to a Ø40 lobe at y 100, 2.5 walls; Ø40 / Ø35 flue 132.6 long down from the chamber; vents in the top; ears with Ø4.5STEP · STL
ta-shroud-2in-backback half (y ≤ −0.5) of the same band: Ø80 chamber, vents, ears with Ø4.5STEP · STL

Plain text: sheet.txt · JSON: /api/geometry?object=thermoacoustic-hot-shroud

Thermoacoustic hot-head shroud: flame shroud and flue for a vertical 2 in tri-clamp core, isometric render of a generated part
Render of ta-shroud-2in-back from the free STEP; not to scale.

How it fits

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Questions

Why not heat it from below?

The hot exchanger is half way up a vertical core, above the buffer tube; a flame from below would heat the lower clamp, jacket and buffer tube first.

Where does the torch go?

On the bench under the flue, its head in the torch stand's ring with the ring top 25 mm below the flue.