Ogge wrote:IMHO a standing wave is just bleeding energy out of the working cycle. The standing waves are not moving (ie standing), they are pulsating pressure transveresly, inducing vibrations in the walls of the tubes. The walls of the outer tube thus induce traveling waves into the air in the form of sound to the outside observer.
Adam, we are not getting to you, are we? You are having opinions based on what?
You do not seem to understand the nature of resonance at all. It is a complete opposite of what you seem to think it is.
No it is not
a waste of energy. It is conservation
of energy. The standing wave is a way for the energy of pulsation to be retained at least partly inside the engine, so that it can be used for aspiration.
What the hell is it that gets reflected back into the engine from the end of the tailpipe but energy? What the hell are waves but energy, pure and simple? It is mechanical energy stored in the gas. We use it to drive teh pulsejet cycle.
The fact that PDEs are not really pulsating, but are single-shot machines has clouded your thinking. Pulsejets pulsate. Their cycle is recurring, a self-excited relaxational oscillation.
Pulsejets thus provide their own automatic aspiration. Without a standing wave, this is extremely difficult to achieve. Without it, you have to have ancillary equipment to purge your engine of combustion products and to refill it with fresh charge. You seem to be thinking purely of combustion, but combustion is only half the cycle. What about the other half?
No, the standing wave is not
a by-product. It is the part and parcel of pulsating combustion. The only non-acoustic pulsating combustion device I know of is the Reynst combustor -- the original pot burner he patented in the 1920s. Add a resonator to it and its operating frequency goes up by an order of magnitude, while at the same time increasing in amplitude
. Figure out how much the energy utilization improves. So, where do you see the loss? I can only see amazing gain.