How to achieve ultra-high power: piston-supercharged propane gun?

[yyt]

This method will challenge the liquefaction limit of propane, exceeding the compression of 20 MPa, and may even reach the energy density of gunpowder. I have been thinking about it for several days and finally believe that this is achievable. Next, I will briefly describe my idea: There are three chambers, named a, b, and c. The volume of a is equal to that of b (this is not certain, there is room for optimization). The volume of c is only one-tenth of a or b. Let's connect a, b, and c in turn, with a bursting disc blocking each chamber. Now, inject 1 MPa of propane-air mixture into a, and inject pure 1 MPa compressed air into b. By the way, there is also a piston in chamber b. Inject pure propane into c, and the volume of propane is calculated based on the total amount of compressed air in chamber b. Now, ignite the propane-air mixture in a, it will break through the bursting disc between a and b, push the piston inside b to move toward c, and further compress the air inside b. When the piston approaches c, the bursting disc between b and c opens. At this time, the high-temperature and high-pressure air that has undergone secondary compression will rush into c, impacting the pure propane inside c, causing them to mix rapidly and reach the ignition point of propane. At this time, an unprecedented huge explosion will occur inside c, even exceeding the energy density of gunpowder.

[yyt]

Let's simulate it. The volume of a is 100cc, the volume of b is also 100cc, and the volume of c is only 10cc. When a explodes, the piston of b moves to the position of c, which is equivalent to compressing it 10 times. The interior of b is originally filled with 1MPa compressed air, which is equivalent to the volume pressure of the small chamber of c becoming 10MPa. Then the explosion pressure should be 10*7=70MPa. When I asked AI if this was correct, it gave me an even more shocking reply: This is an adiabatic compression. I did not consider the thermal expansion effect of the air, which means that in fact, the pressure effect caused by the volume change cannot be considered alone. The temperature of the air is also important. AI told me that when the piston of b moves to c, the air pressure in c will reach 30MPa. The mixture ignited at this pressure will have an explosion pressure of 210MPa! I only used the original input of 1MPa and finally obtained a final pressure of 210MPa. This is an incredible power amplifier!

[yyt]

This is actually another form of compression ignition, except that the power of the spring or crankshaft is replaced by the pressure of the explosion of the mixture. I think the biggest advantage of my design is that it avoids the premature ignition of propane by the traditional compression ignition method. If I remember correctly, the propane-air mixture will ignite under 25 times the adiabatic compression, but when I store propane and air separately, this will no longer be a problem. Their ignition pressure will depend entirely on the release pressure of the bursting disc between b and c. Another additional benefit is that this design supports the full combustion of liquid propane, because when the high-pressure air hits chamber c, all the liquid will be dispersed to form tiny particles, allowing them to be fully mixed with the air. The energy density at this time is close to that of solid propellant, because this is the full combustion of liquid propane.

[D_Hall]

If you want to jump through all those hoops with so many burst disks... Just go with a two stage design and use methane both as your primary fuel and as your second stage gas. Granted, hydrogen or helium would be better, but methane is still prettttty damned good and it's available in any house that has gas heating. As a bonus, the muzzle flash of such a gun would be impressive.