Why such program is necessary? It's as simple as... 1 cent
.When you need to build just 1 small valveless engine, you can cut, weld, re-cut and re-weld as much as you like - your costs will not be high in any case, even if you spend a couple of hundred extra dollars
. And this way of engine research is cheapest, really.But it's a completely different matter when you need 10,000 engines, preferably per month
. Then the slightest mistake can easily cost you hundreds of... thousands dollars 
. This is what requires at least some reasonable choice of parameters.We created our model and the program, because in our conditions, designing with a cutter and welding is completely impossible, in principle and by definition. Because research by cutting and welding is extremely expensive
. Feel the difference .If it is clear, then look at the first results for a small engine - this is the choice of the optimal length of the intake pipe and the choice of the optimal length of the resonance pipe. Although these names are conditional - in a valveless engine, both pipes are resonant and both create thrust, and the intake even more than the exhaust. It's just that the exhaust pipe is very long, and the air does not have time to pass through it completely during the cycle (only on about 25% of length).
This study was made for the engine with the combustion chamber 80x300 mm, the cone 150 mm length, 40 mm diameter of the resonant pipe and 50 mm diameter of the intake pipe. Result gives the optimal length about 300 mm for the intake pipe and about 1100-1300 mm for the resonant pipe.
The good thing is you can get such curves by pressing just 1 button in program
. But as it is usual with all business the bad thing exists too... 
Unfortunately, the program cannot conduct research and obtain the absolute optimum-maximum for 2 parameters at once. Therefore, it will be necessary to make several parametric modeling like this (to press the button several times
). Also, the program still cannot modeling gas flow in conical resonant pipes, only in cylindrical (cone helps to decrease the pipe length, therefore our program gives some oversized optimal length). But we are sure all this is not a critical problem - the main thing is to start...
P.S. Sometimes parametric modeling doesn't work or works incorrectly - it means that our electronic guys are doing something there, and perhaps everything will work again soon
. Unfortunately, it is very difficult to make such a model completely and always workable, even if it looks simple...