Test · 2023-07-15
S-type layout: does cold need to sit above hot?
The question
Does a thermoacoustic engine's cold end have to be directly above its hot end?
The answer
No, not strictly. An offset S-type layout assembled from tri-clamp parts whistled, then self-started with a diaphragm. The cold end must be higher, not necessarily directly above.
- Kind
- Test
- Status
- Built
- Date
- 2023-07-15
- Layout
- Offset (S-type)
Video
What it is
A viewer question answered with a quick build: hot section, stack and cold section joined at an offset with tri-clamp fittings.
Results
- →Audible tone first, confirming oscillation.
- →Diaphragm with one magnet self-started.
Lab notes
Valves tried
A water balloon made the best one-way valve of anything tested but melts at operating temperature. A small black duckbill valve became the standard and ships with engines.
Notes transcribed from the build video.
Related
Does the design still work scaled to 3 feet?Yes. It runs at 3 ft, and it's the channel's most-watched build.See more →Does less air make the engine run faster?Yes. Venting the excess lets the small air volume oscillate faster.See more →Can the clamp itself be the heat sink?In simulation, yes. About 2× the heat rejection in still air. Not yet built.See more →
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