I have been browsing ebay for radiator fan blades, there are many different styles of the 7 blade version. Blades with the corners cut from the back of the blade, the front of the blade, rounded edges ect. My question? does any of these different shaped blades serve any purpose other than design curiosity??
From a Physics Forum: "Do realize that fan shape is an extremely active area of research. We are always looking for ways to tweak our fan blade designs to achieve exactly what you are asking about. In regards to noise, the tip geometry is pretty much king. That's where you are sure to go supersonic and that is where the noise is generated."