ENGR 100 Lecture Notes - Lecture 17: Darrieus Wind Turbine, Freerunning, Aerodynamic Force
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Efficiency is the ratio of power out to power in: by conservation of energy, < 100% (pout-pin) is the po(cid:449)er (cid:862)(cid:449)asted(cid:863, often turns into heat if the process is(cid:374)"t (cid:373)atched, it just does(cid:374)"t co(cid:374)(cid:448)ert. End-to-end efficiency: pout = pload = vload, pin = pwind = at u3. Free= (u/l) {(cd2 cd1 )/(cd2 +cd1 )} =(1/16) ap {cd2 cd1 }2u3/(cd2 +cd1 ) Sav= (1/8) (ap /at)(cd2 cd1 )2/(cd2 +cd1 ) Scaling, step 1: find the operating point: adjusting the operating point things to adjust and take into account. Scaling, step 2: adjust the operating point (eg. gear ratio) turbine cross section. Aspect ratio (aka height to width ratio) load resistance stepper motor configuration (phases) Remember: in order to get more power, make it bigger. Scaling, step 3: bigger by making savonius taller x2. Scaling, step 3: bigger by making savonius taller. If you like your design (efficiency, etc) but just want more power:
