may i ask you 1 question, now i'm doing my master project in savonius rotor. i read many jurnal about aspect ratio. some of them said it's good to have high aspect ratio and some of them said the low aspect ratio is the best. my question is, which one is the best? having high aspect ratio or low...tq sir...
Dear sir, I don't have a 100%-sure answer of your question, but let's think together. I want you to put in mind that there may be another constraints rather than the aeodynamic ones.
Assume that you have a fixed blade profile diameter and you want to change the aspect ratio. Actually, there are two methods to change the aspect ratio. The first method is changing the primary gap (blades overlap which is the distance between inner blades' tips), and this has an optimum value which is 20%-30% of rotor diameter. You can test the effect of this gap -if you want- by using the shown construction of Savonius turbine. The second method is changing rotor height. Smaller heights will reduce efficiency due to turbulence at the bottom and the top of the rotor, and if the rotor height is small enough the turbelence zones may interfer. On the other side, I don't know what larger heights may lead to (aerodynamically), but larger heights lead to high bending moments on shaft, strong vibrations, and difficult installation. I'll do some extra search for you to get the best answer.
may i ask you 1 question, now i'm doing my master project in savonius rotor. i read many jurnal about aspect ratio. some of them said it's good to have high aspect ratio and some of them said the low aspect ratio is the best. my question is, which one is the best? having high aspect ratio or low...tq sir...
ReplyDeleteDear sir, I don't have a 100%-sure answer of your question, but let's think together. I want you to put in mind that there may be another constraints rather than the aeodynamic ones.
DeleteAssume that you have a fixed blade profile diameter and you want to change the aspect ratio. Actually, there are two methods to change the aspect ratio. The first method is changing the primary gap (blades overlap which is the distance between inner blades' tips), and this has an optimum value which is 20%-30% of rotor diameter. You can test the effect of this gap -if you want- by using the shown construction of Savonius turbine.
The second method is changing rotor height. Smaller heights will reduce efficiency due to turbulence at the bottom and the top of the rotor, and if the rotor height is small enough the turbelence zones may interfer. On the other side, I don't know what larger heights may lead to (aerodynamically), but larger heights lead to high bending moments on shaft, strong vibrations, and difficult installation. I'll do some extra search for you to get the best answer.