Do you have a drake? Without one, you wont have fertile eggs.
Can I ask why you are expecting her to go broody? Many domestic ducks will never go broody. Just because she is laying eggs doesn't mean she is going to hatch them. Domestic ducks don't have a season where they will lay a clutch of eggs to hatch them. They will lay year round, only taking a break in winter to molt.
You will know if she is broody if she is flattened on her nest all day, hissing when you approach her. If she is acting normal, she is not broody and there is no point in leaving the eggs out. The eggs will just spoil sitting outside.