Did you read about TASHE Stirling engine yet?
This is a thermoacoustic traveling wave engine with Stirling-like cycle.
Thermoacoustic engines are working with a fantastic phenomena.
A short historical list about thermoacoustics:
The first TA engine came from Byron Higgins 1777!!! but it was recorded first at 1802.
He made the first singing flame with Hydrogen where the gas burned in a tube.
BUT
Do you hear about singing drums from Japan?
They are made from a rice coocker drum. The water heated up.
In the middle of the drum they put a screen to hold the rice.
When the steam is growing in the drum they put the rice onto the screen and the
thermoacoustic (or steam thermoacoustic) oscillation will start soon.
The first written memory about this effect came from a Buddhist monk
1568
OMG!
Anyway the next experiment came from Sondhauss who made the "flameless" singing bulb.
The bulb was heated up and the neck tube was cooled in 1804.
Later Rijke made a straight tube with heated gauze in.
The first real developement started in the early 30s
in the military segment for the pulse jet V-1 buzz bomb.
It worked with a combustion-induced oscillation.
They've made few different versions with also without valve to increase the efficiency.
The space program given the next generation of the pulse jet rockets around 1960.
-o-
The peaceful thermoacoustics is started with Ceperley and Wheatley from Los Alamos National Laboratory.
They started to develop a standing wave engine with resonator and stack base regnerator with two heat exchangers.
The next generation of standing wave thermoacoustic engine came from Greg Swift.
It has 700W acoustical energy with 9% thermal and 13% of Carnot efficiency.
The first traveling wave thermoacoustic device developed by Yazaki
but he used stack based regenerator yet.
The first regenerator based working looped traveling wave TASHE was demonstarted by
Swift and Backhaus...
and soon Tijani and Spoelstra.
The Tijani's engine worked with 49% of Carnot at 40 bar of Helium
generated 280W
etc...etc...etc...
The original TASHE needs a resonator tube.
It was changed later to mechanical resonator.
The mechanical resonator is a mass-spring system.
This system radically reduces the losses compared to the acoustical resonator.
So anyway, we have lot of papers about the thermoacoustics
also from TASHE engines but only for industrial, millitary, or space applications.
The hobbyist Stirling builders all around the world don't really know this type of engine.
Stirling-guys really like the crankshaft and the joints movement, the knocking noises etc.
The model engineers could make nicely machined desktop toys
like this one
or this one
The youtubers are started to make Stirling engines from scrappy parts.
The most popular the soda, soft dring, energy dring, beer can
based Stirling engines with folded crankshaft and rods:
You could find hundreds of videos about gamma and beta type engines.
I've started to make no crank
beta
free piston Stirling engines
few years ago.
This confgiguration is the most popular design I've ever made:
I started to design a more simple beer can Stirling engine
when I meet with an interesting video on TK motor's channel.
It was an annular designed TASHE engine with conical shaped ends and it worked with membranes.
The membranes could help to reduce the Gedeon streaming in the loop.
That stream is a gas flow where the acoustic fluctuation goes.
It could reduce the cycle efficiency.
So the membrane could stop this flow and also it could substitute some gas volume because the gas in tube has mass and elasticity aka spring constant. So it is a spring-mass system.
My friend Tibsim is made an interesting video in his channel about how the gas "piston" moves in the tube
also how the heat start to amplificate this movement:
You could calculate how long could be a full wave length looped thermoacoustic engine at 20˙C and 50Hz.
343,4 m/s : 50 = 6,868 m
So it is a big circle.
The inner geometry and the membranes gives some possibility to reduce the loop's length drastically
because what we want
that is a pressure swing phase shift in the regenerator.
This is a complicate calculation originally few program could help to reduce the optimization,
but I found an easy way how to make a DIY simple
free piston TASHE (thermoacoustic Stirling heat engine) also I made a tutorial for that.
No calculations, no expensive tools, just a simple and working model.
The first working prototype was made with accordion piston, but I realise it is not available for everyone, so I started to develop a latex balloon version from this.
The frequency increased so much.
30--> 60+ Hz
The membranes tighteness and the mass on that is important to tune the frequency.
The engine works well and stable as possible with this low budget configuration.
If you want to build yours, please leave me a link bellow for your replications!
See You Soon!
BLADE