Sviluppo di un ventilatore assiale con palettatura a doppio profilo per il raffreddamento del sottocofano di macchine agricole

The internal configuration of a modern farm-tractor bonnet is characterized by the presence of several cooling elements that cause important head losses to the air-stream passing through the whole system. Considering the negligible speed at which the agricultural machinery operates, it is clear that, to the fan, a significant amount of work is required to pull down the mentioned head losses and to supply, at the same time, the airflow that is needed to the cooling system itself. For that reason, usually, the blade stagger angle is increased raising its stall limit. Starting from that, in the present work, a new fan with a twin-airfoil blade has been designed, realized and tested both in the testing chamber and under-bonnet of a mid-power class tractor. The satisfactory results, obtained after the testing activities carried out, have confirmed all that was emerged during the design phases both in terms of work exchanged and efficiency level exhibited by the fan. The important level of aerodynamic load reached by the new shaped blade has allowed to decrease the number of blades with positive effects in terms of noise reduction.