Index Circular Stirling Stirling program source code Links
Dual Circular Alpha Siemens Alpha Beta Gamma

Circular gamma type Stirling engine animation.
power piston
displacer
gear wheel
displacer crank displacer crank power piston crank connection crank with connecting rod power piston crank
displacer gear wheel displacer crank power piston crank power piston crank
hot gas in heater tube or expansion space.
heater
regenerator
hot cap
displacer
connecting duct
cold gas in cooler tube or compression space
cooling water
power cylinder wall
power piston
gear wheel
displacer housing wall
power piston connecting rod
gudgeon pin (UK, wrist pin US)
power piston crank
displacer crank
crankshaft
Degree of cycle (of cylinder 1).
degree of cycle
0 30 60 90 120 150 180 210 240 270 300 330 360
Animation speed (cycles/minute.) Stops after 3 minutes.
animation speed
0 5 10 15 20 25 30 35 40 45 50 55 60
Info to calculate movements. -----------
 1. crank angle between the cranks on the crankshaft.
 2. Angle between the two cylinders. Often 0 or 90 degrees.
 3. ?
 4. cm, crank radius of the power piston cranks.
 5. cm, length of the power piston connecting rod.

Info to calculate active volumes and volume changes. -----------
 6. cm, length of the displacer.
 7. cm, diameter power piston cylinder.

Info to calculate dead volumes. -----------
 8. cm, power piston end clearance.
 9. cm, displacer clearance at crankshaft side of the displacer housing.
10. cm, diameter sealing at crankshaft side of the displacer housing.
11. cm, displacer clearance at the back side of the displacer housing.
12. cm, diameter sealing at the back side of the displacer housing.
13. cm, minimal gap between the displacer and the housing on the rounded side.

Click on this button to recalculate the output values below.
CALCULATED OUTPUTS.

%
100-
90-
80-
70-
60-
50-
40-
30-
20-
10-
0-
 Volume, red= hot, green= total, blue= cold
( % of maximum total volume)
c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c
0 30 60 90 120 150 180 210 240 270 300 330 360
Angle degree

HOT DEAD VOLUMES
= crank side end clearance dead volume, cm^3.
= back side end clearance dead volume, cm^3.
= hot cap gap side end clearance dead volume, cm^3.
+ -------------
= hot displacer end clearance dead volume, cm^3.
= power cylinder dead volume, cm^3.
= dead volume, because both active volumes are not 100% filled at the same time, cm^3.
+ -------------
= total hot dead volume volume, cm^3.
HOT ACTIVE VOLUMES
= power cylinder active volume, cm^3.
= hot displacer active volume, cm^3.
= subtraction, because both active volumes are not 100% filled at the same time, cm^3.
+ -----------
= total maximamum hot active volume, cm^3.
COLD VOLUMES
= cold displacer dead volume, cm^3.
= cold displacer active volume, cm^3.
+ -----------
= total cold volume, cm^3.
MAXIMUM VOLUMES
= maximum hot active volume, cm^3.
= total maximum hot volume, cm^3.
= maximum cold active volume, cm^3.
= total maximum cold volume, cm^3.
= total maximum engine gas volume (outside regenerator, heatpipes and coolpipes), cm^3.
AREAS
= power piston area, cm^2.
= displacer house cross section area, cm^2.
= displacer cross section area, cm^2.

ROTOR CONSTRUCTION
cm.= radius of the cirkels to draw the trochoid shape = diameter of inner gear wheel =radius of the outer gear wheel.
cm.= minimal width of the rotor. drawing of the shape of the trochoid rotor cm.= maximum distance from the crank.
cm.= minimal distance from the crank.
cm.= maximum width of the rotor.
cm.= is the crank radius, also the grid spacing in this picture, and the radius of the inner gear wheel.
cm.= outside diameter of the cylinder where the displacer rotor can be made of.
The green cross (X)is the place where the crank goes through the rotor.
ROTOR HOUSE CONSTRUCTION
cm.= Distance between the sealings in the housing wall to separate the upper and lower chambres.
cm.= inner height of the rotor housing. Drawing of the shape of the rotor housing. cm.= distance between the center of the crankshaft and the top of the rotor housing.
cm.= crank radius = spacing of the grid.
cm.= maximum width of the rotor housing.
The green circle (O)is the circle where the heart of the crank goes through the rotor.
The white circle (O)is the pitch circle the internal gear on the rotor.

Equivalent sizes for a cylinder replacer to use in a stirling design program:

Use the same crank radius.
For the length of the connecting rod, take a big size, like 9999999. If the program does not ask for this input, it means that the program assumes that the gas displacement is sinodial. This is not exact the case for piston-connecting rod-crank combination, but perfect for this type of circular displacer.
cm.= cm, is de equivalent piston diameter, or cylinder diameter to use.