In my opinion, I would take the insulation out of the inside of the box. Fist off, it is going to be a pain to clean out, even with filters on the front, you will need to clean it every once in a while. Second, on a car, the muffler is to quiet the exhaust of the detonation of the compressed air fuel. Also a car muffler provides a certain amount of back pressure, which is needed for optimal efficiency on todays cars. Dynomat is used on the inside of the car to keep vibration noise from outside the car out. You want to keep the vibration noise from inside that muffler box you created in. So put the sound mat on the outside. This will also help to insulate the temp from inside the muffler from transfering to inside the pc box. Third, by making the intake hole of your box larger, (if those drawings are close to scale), so that they are approx the same size as the diameter of the hole on your two fans combined. This will help to stop the amount of compression that the air is having to go through the intake, and the expansion of air after the radiator on the exhaust. Try http://www.flowmastermufflers.com/mufflers.html for some fundamental designs on mufflers. While these are made more for air flow, than noise reduction, keep in mind that they are dramaticly reducing the sound of an un-mufflered engine to an acceptable db level. While fans are no competition for a car engine, I think that you could at least get another perspective on how a few others have designed mufflers. I think your design is pretty impressive. I am not an expert on muffler design, but have "modified" the glass packs on my vehicles to make them louder, I have however spent some time in mechanics class to learn how to build most of my own parts for cars if something breaks down, or needs to be tweaked.
I sorry but wat are you on about. i dont know if the design will be effactive but in this case its the fan that makin most of the nose as it fins cut though the air. so it wud work like a car muffler but i think a set of good quiet fans would be cheaper and just as effective and maby even water cooling.
You're losing me here. Put the insulation mat (bitumen+foam) outside? Now that would hardly make any sense, since only thing the mat would do is increase the mass of the wall it's attached to. Sure, this serves the vibration problem but the foam can't do it's job and the noise can escape with ease. Besides, the effect of the mass increase is basically the same regardless to which side you glue the bitumen on, however, as the bitumen has rougher surface than your basic panel, it would work as small diffusor, which basically would slightly decrease the noise. First of all, you should also increase the diameter of every hole in the muffler. Surely, that would increase flow BUT it would also result to increased noise. Basically, the larger holes you've got, the greater the noise will be. Just like your mouth. Besides, axial fans aren't really capable of producing pressure so the compression/decompression is nothing you should worry about.
Yep, increasing the diameter of the holes will reduce the effectiveness of the muffler. When I go into build phase I think I will have to experiment with the dimensions of the muffler and the diameter of the holes to get the ideal airflow and sound reduction. The sound absorbing foam needs to be in the inside of the muffler to do just that - absorb sound. Absorbed sound energy is converted to heat. The layout of the pipes ensures that sound waves can't travel in a straight line and therefore bounce off the sides covered with the foam. Doing thus increases the opportunity for sound absorption.
Aren't there other ways to make your PC silent than having incredibly huge mufflers on all the air inlets and outlets? Is the purpose of this design to be silent or to incorporate all these mufflers? I'd go with huge, undervolted fans and many-finned copper heatsinks wherever possible. And separate the hotter hardware into sections to isolate them. But that's just me.
The idea is to have a quiter setup. The Vapochill unit requires substantial airflow and is prety mush set in the way it's laid out. Hence the mufflers design.
Sorry for not clarifing, yes put the mat on the outside, the foam I was not refering to. I would not use the foam as even though this case is going to be large, adding foam insulation on the inside would mean that you would want to increase the size of the inner chamber to reflect the volume lost by the volume of the foam. The mat on the outside doesnt only reduce sound by adding density alone. Our good friends at www.dynamat.com can help by providing the following to help us all out a little here: The acoustic loss factor "n" is used as a measure of a material's ability to damp structure-borne sound by stating how much vibrational energy (in steel sheets for instance) is converted to heat rather than sound. For constructions containing several layers of damping material, the combined loss factor "n comb" is used. The theoretical maximum loss factor is 1 (no vibration). An undamped 1mm thick steel panel has a loss factor of roughly 0.001 at 200 Hz. Dynamat Xtreme applied to that panel would increase the loss factor to 0.417 @ +20°C (+68°F). Multiple layers of Dynamat Xtreme improve sound damping even more. In other words, use sound mat to dampen the muffler itself, use the baffles and chambers to baffle the air itself. I never said to not increase the sizes of all ports on the muffler. However, you can make multiple ports for air to passthrough without having to increase their size. The different angles of the baffles and chambers inside the muffler, are supposed to do most of the work of making the air use the most indirect route out, without adding much restriction. Changing the size of the ports should be something to experiement with, as making ports too large can deepen the sound, and on the flip side, making the ports too small can make sound higher pitched. The same idea goes along with how long the air is traveling. ( I almost hate to through another example on here, but think long air passageways as a trombone, different size ports as the difference in size between the mouthpeice and the end horn. If you cut the end horn off, and bring the size of that peice of tubing down to the same size of the mouthpiece, you will notice a huge difference in db. Just an analogy of what I am trying to convey, not a direct example of a muffler.) As to the pressure statement, I was trying to use an example of something familiar to most people, maybe not the most perfect example, but it is similar in one aspect I was trying to describe how some cars are not that quiet with high performance mufflers, but are still dropping the Db from open headers. If I had not put that sentance in there, I am sure someone would have said, and already said, that car mufflers are to reduce combustion engines. We are not talking about a car muffler, I just wanted to use an analogy.
