"Whistle blew" is a common phrase used to describe the sound of a whistle being blown, but there are several synonyms to use in its place. One option is to say that a whistle sounded, which has a similar meaning. You could also use the phrases "whistle blared" or "whistle screeched" to add more emphasis to the sound. Another option is to use "whistle hooted" or "whistle tooted," which sound more playful and friendly. Finally, you could go with the classic option of "whistle blew loudly" or "whistle burst forth," emphasizing the power and volume of the sound.