Build up a head of steam:
To gradually become more and more angry, anxious, or emotional about something until you can no longer hide your feelings.
旧时，蒸汽机在启动后需要先 “build up a head of steam（蓄足蒸汽压力）” 才能全力运转。如今，这个表达用来比喻 “某事或人开始成功”，尤其指 “一个人或一项活动积攒了足够的能量、人气或支持，从而促使某事的发生”。
例句
The new advertising campaign is building up a head of steam. The product is really selling.
这个新的广告宣传活动初见成效。这款产品真的很畅销。
The team is building up a head of steam after a slow start. The presentation should be ready by Friday.
这支团队在缓慢起步后渐入佳境。演示报告应该在星期五之前准备好。
We really need to build up a head of steam if we want to finish this project on time.
如果我们想按时完成这个项目，我们真得蓄足马力。
