What makes internal combustion engines accelerate?

Question

So if an internal combustion engine is idling, when we add more gas/air by opening the throttle why does the engine accelerate? Do the explosions in the cylinders increase in velocity? I would have assumed that the explosions occur at the same speed regardless of the amount of fuel/air in the cylinder. So I don’t understand why the engine rpm increases.

thanks

In: Engineering

Answer 1

It is not an explosion, it is deflagration.

Explosions (aka detonations) are supersonic. Deflagration is subsonic.

Just by these definitions you can see that the flame front can have different speeds.