# Regenerator screen disc: Ø47.5, 100 mesh × 0.10 mm wire

> What screen should a 2 inch thermoacoustic regenerator use?

- Category: Stirling engines › Heat & regenerator
- Kind: Hardware
- Basis: Woven-screen geometry from Swift (porosity 1 − π m d / 4, hydraulic radius φ d / 4(1 − φ)); friction from Swift & Ward
- Page: https://xemstudio.com/objects/regenerator-screen-disc-47-5/ · JSON: https://xemstudio.com/api/geometry?object=regenerator-screen-disc-47-5 · Plain text: https://xemstudio.com/objects/regenerator-screen-disc-47-5/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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.

## Notes

- A disc of 100-mesh woven screen with 0.1 mm wire, cut to the 2 in bore (Ø47.5) and drawn as a solid disc 0.2 thick (two wire diameters, the thickness of one woven layer). Stacked, the discs fill the regenerator: 500 per ring-engine core (100 mm), 550 in the twin engine (110 mm).
- Porosity 0.69, hydraulic radius 56 µm: about a tenth of the helium's thermal penetration depth at 25 Hz, which is what a traveling-wave regenerator wants (gas and screen at the same temperature, pressure and flow in phase).
- No centre hole: nothing passes through these regenerators.
- Fit: the disc edge is a slide fit in the bore; a gap at the edge would let gas bypass the screen.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| disc edge | Ø47.5 | 2 in spool bore: no bypass at the wall | slide | all |
| thickness | 0.20 (100 mesh × 0.10 wire, one woven layer) | the next disc | designed | all |

## Sizes

| feature | value |
|---|---|
| diameter | Ø47.5 |
| mesh | 100 per inch |
| wire | 0.1 mm |
| layer | 0.2 mm |
| porosity | 0.691 |
| hydraulic radius | 55.9 µm |

## Where the files are

- G. W. Swift (Acoustical Society of America / LANL): [Thermoacoustics: A Unifying Perspective for Some Engines and Refrigerators (Rott's equations, the energy equation, screen relations; the method behind DeltaEC)](https://www.lanl.gov/org/ddste/aldps/materials-physics-applications/condensed-matter-magnet-science/thermoacoustics/) — web, book — cited (verify at link)
- J. Thermophysics and Heat Transfer (G. W. Swift, W. C. Ward): [Simple harmonic analysis of regenerators, 10(4), 652-662 (1996): stacked-screen friction c1(φ) = 1268 − 3545φ + 2544φ²](https://doi.org/10.2514/3.842) — web — journal article; cited (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/regenerator-screen-disc-47-5/index.json

- screen-disc-47.5-m100: [STEP](https://xemstudio.com/files/hardware/regenerator-screen-disc-47-5/screen-disc-47.5-m100.step) · [STL](https://xemstudio.com/files/hardware/regenerator-screen-disc-47-5/screen-disc-47.5-m100.stl) — woven screen disc Ø47.5 × 0.2 (two wire diameters): 100 mesh, 0.1 mm wire, the regenerator of the generators

## Questions

**How many discs?**

Length ÷ 0.2 mm: 500 for 100 mm.

**Why not wool or a scrubber?**

Those pack unevenly; stacked screens give a known porosity and hydraulic radius, which the model needs.

## Fits with

- [Regenerator matrix disc Ø44 / Ø32 × 0.5 mm (mesh counts #40–#200)](https://xemstudio.com/objects/regenerator-mesh-disc/)
- [Thermoacoustic slotted exchanger insert: 2 in bore, 14 and 12 mm](https://xemstudio.com/objects/thermoacoustic-slotted-exchanger-insert/)
- [Build list: Thermoacoustic-Stirling ring generator, three 2 in units, pressurised](https://xemstudio.com/objects/list-ta-ring-3x2in/)
- [Build list: Thermoacoustic-Stirling engine with twin free-piston alternators, 2 in, pressurised](https://xemstudio.com/objects/list-ta-twin-piston-2in/)