Thermoacoustic jet pump: 2 in, Ø20 to Ø8 taper — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/thermoacoustic-jet-pump/  (CC BY 4.0)
Basis: Backhaus & Swift's jet pump: an asymmetric orifice whose minor-loss difference between the two flow directions sets a steady pressure drop that opposes Gedeon streaming
Catalog version: 2026-10-20

Sizes: see table below
- A torus lets the gas drift steadily round the loop (Gedeon streaming), carrying heat from the hot exchanger straight to the ambient one. A tapered hole loses more pressure on the flow out of its small end than into it, so it sets a steady pressure difference that can cancel the drift: Backhaus & Swift's jet pump.
- Here a Ø47.5 plug, 30 long, sits in the junction cross's lower branch on the gasket lip, its taper from Ø20 (junction) to Ø8 (the ¾ in inertance line). The linear model counts it as a duct of the mean bore.
- Only the twin-piston engine needs it: in the ring engine the pistons themselves block the loop.

feature  value
outside  Ø47.5
taper  Ø20 → Ø8
length  30

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- J. Acoust. Soc. Am. (S. Backhaus, G. W. Swift): A thermoacoustic-Stirling heat engine: detailed study, JASA 107(6), 3148 (2000): torus with inertance and compliance, thermal buffer tube, jet pump against Gedeon streaming — web — journal article; cited [verify license at link] — https://doi.org/10.1121/1.429343
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/thermoacoustic-jet-pump/index.json
API: https://xemstudio.com/api/geometry?object=thermoacoustic-jet-pump