Whir (verb)

1. To make a continuous low humming sound.
2. To move or cause to move with a whirring sound.

Origin:

Middle english whirren, from old english hwyrran; akin to old high german hwirren to whir.

Examples:

1. The fan whirred in the background.
2. The motor whirred as it came to life.
3. The camera whirred as it took the picture.
4. The bird's wings whirred as it flew by.
5. The machine whirred as it printed the documents.